:root{--ink:#152b3a;--ink-soft:#405766;--paper:#f7f4ec;--paper-deep:#eee8dc;--surface:#fffdf8;--teal:#0f766e;--teal-dark:#0b514d;--teal-soft:#d9eeea;--orange:#d9642d;--orange-soft:#f9dfcf;--blue:#4662d9;--blue-soft:#e0e6ff;--yellow:#f0c24d;--line:#d7d2c7;--line-dark:#152b3a2e;--shadow:0 18px 55px #21303c1c;--radius-lg:28px;--radius-md:18px;--radius-sm:11px;--content:1180px}*{box-sizing:border-box}html{scroll-behavior:smooth}body{background:var(--paper);color:var(--ink);margin:0;font-family:Aptos,Segoe UI,Arial,sans-serif;font-size:16px;line-height:1.55}button,input,select{font:inherit}button,a,input,select,summary{-webkit-tap-highlight-color:transparent}:focus-visible{outline:3px solid var(--yellow);outline-offset:3px}a{color:inherit}h1,h2,h3,p{margin-top:0}h1,h2,h3{letter-spacing:-.035em;line-height:1.08}h1{margin-bottom:28px;font-family:Georgia,Times New Roman,serif;font-size:clamp(3.25rem,7.5vw,6.9rem);font-weight:500}h2{margin-bottom:0;font-family:Georgia,Times New Roman,serif;font-size:clamp(2.2rem,4.6vw,4.35rem);font-weight:500}h3{margin-bottom:12px;font-size:1.35rem}.sr-only{clip:rect(0, 0, 0, 0);white-space:nowrap;border:0;width:1px;height:1px;margin:-1px;padding:0;position:absolute;overflow:hidden}.site-header{z-index:50;min-height:72px;padding:12px max(24px, calc((100vw - var(--content)) / 2));-webkit-backdrop-filter:blur(15px);backdrop-filter:blur(15px);background:#f7f4ecf0;border-bottom:1px solid #152b3a1f;grid-template-columns:auto 1fr auto;align-items:center;gap:28px;display:grid;position:sticky;top:0}.brand{align-items:center;gap:10px;text-decoration:none;display:inline-flex}.brand-mark{background:var(--ink);color:#fff;border-radius:50%;place-items:center;width:42px;height:42px;font-family:Georgia,serif;font-size:.88rem;font-style:italic;display:grid}.brand>span:last-child{flex-direction:column;line-height:1.05;display:flex}.brand small{color:var(--ink-soft);letter-spacing:.08em;text-transform:uppercase;margin-top:5px;font-size:.72rem}.site-header nav{justify-content:center;gap:clamp(14px,2.2vw,32px);display:flex}.site-header nav a{color:var(--ink-soft);font-size:.9rem;font-weight:700;text-decoration:none}.site-header nav a:hover{color:var(--teal)}.teacher-switch{cursor:pointer;white-space:nowrap;align-items:center;gap:9px;font-size:.9rem;font-weight:700;display:inline-flex}.teacher-switch input{opacity:0;pointer-events:none;position:absolute}.teacher-switch>span{background:#aab5ba;border-radius:999px;width:42px;height:24px;padding:3px;transition:background .16s;display:inline-flex}.teacher-switch>span:after{content:"";background:#fff;border-radius:50%;width:18px;height:18px;transition:transform .16s;box-shadow:0 1px 4px #00000040}.teacher-switch input:checked+span{background:var(--teal)}.teacher-switch input:checked+span:after{transform:translate(18px)}.teacher-switch input:focus-visible+span{outline:3px solid var(--yellow);outline-offset:3px}.hero{min-height:760px;max-width:var(--content);grid-template-columns:minmax(0,1.24fr) minmax(330px,.76fr);align-items:center;gap:60px;margin:0 auto;padding:108px 24px 88px;display:grid}.eyebrow{color:var(--teal);letter-spacing:.15em;text-transform:uppercase;margin-bottom:14px;font-size:.78rem;font-weight:800}.hero-copy .eyebrow{color:var(--orange)}.hero-lead{max-width:720px;color:var(--ink-soft);margin-bottom:32px;font-size:clamp(1.08rem,1.7vw,1.28rem)}.hero-actions,.playback-row,.worksheet-toolbar,.check-actions{flex-wrap:wrap;align-items:center;gap:10px;display:flex}.button{border:1px solid var(--line-dark);min-height:44px;color:var(--ink);cursor:pointer;background:0 0;border-radius:999px;justify-content:center;align-items:center;padding:10px 18px;font-weight:750;line-height:1.2;text-decoration:none;transition:transform .14s,background .14s,border-color .14s;display:inline-flex}.button:hover{border-color:var(--ink);transform:translateY(-1px)}.button:disabled{cursor:not-allowed;opacity:.45;transform:none}.button-primary{border-color:var(--ink);background:var(--ink);color:#fff}.button-primary:hover{background:var(--teal-dark);border-color:var(--teal-dark)}.button-small{min-height:38px;padding:8px 14px;font-size:.88rem}.text-button{color:var(--teal-dark);cursor:pointer;background:0 0;border:0;border-bottom:1px solid;padding:4px 0;font-weight:750}.lesson-meta{border-top:1px solid var(--line-dark);border-bottom:1px solid var(--line-dark);grid-template-columns:repeat(3,1fr);margin-top:48px;display:grid}.lesson-meta>div{flex-direction:column;padding:18px 16px 18px 0;display:flex}.lesson-meta>div+div{border-left:1px solid var(--line-dark);padding-left:20px}.lesson-meta strong{font-family:Georgia,serif;font-size:1.55rem;font-weight:500}.lesson-meta span{color:var(--ink-soft);margin-top:3px;font-size:.78rem}.hero-visual{aspect-ratio:1;place-items:center;display:grid;position:relative}.hero-visual:before{content:"";background:radial-gradient(circle at 40% 36%, #fffefb, var(--teal-soft) 58%, #bfded9 100%);box-shadow:var(--shadow);border-radius:50%;position:absolute;inset:5%}.hero-center{z-index:3;aspect-ratio:1;background:var(--ink);color:#fff;text-align:center;border:1px solid #ffffffb3;border-radius:50%;flex-direction:column;justify-content:center;align-items:center;width:48%;padding:24px;display:flex;position:relative}.hero-center span{color:#a9d8d4;letter-spacing:.14em;text-transform:uppercase;font-size:.72rem;font-weight:800}.hero-center strong{margin:8px 0;font-family:Georgia,serif;font-size:clamp(1.2rem,2.5vw,2rem);font-weight:500}.hero-center small{color:#b8c8cf;max-width:150px;line-height:1.35}.hero-orbit{z-index:2;border:1px solid #152b3a40;border-radius:50%;position:absolute;inset:13%}.hero-orbit span{background:var(--surface);color:var(--ink);letter-spacing:.1em;text-transform:uppercase;border-radius:999px;padding:5px 10px;font-size:.72rem;font-weight:800;position:absolute;box-shadow:0 7px 20px #152b3a1f}.orbit-one span{top:-13px;left:50%;transform:translate(-50%)}.orbit-two{inset:22%;transform:rotate(120deg)}.orbit-two span{top:50%;right:-33px;transform:rotate(-120deg)}.orbit-three{inset:31%;transform:rotate(240deg)}.orbit-three span{top:50%;left:-42px;transform:rotate(-240deg)}.outcomes-band{padding:60px max(24px, calc((100vw - var(--content)) / 2));background:var(--ink);color:#fff;grid-template-columns:.7fr 1.3fr;gap:60px;display:grid}.outcomes-band .eyebrow{color:#8fd3cc}.outcomes-band h2{max-width:470px;font-size:clamp(2rem,4vw,3.6rem)}.outcomes-band ul{grid-template-columns:repeat(2,minmax(0,1fr));gap:0;margin:0;padding:0;list-style:none;display:grid}.outcomes-band li{color:#dce5e8;border-bottom:1px solid #ffffff29;padding:18px 24px 18px 34px;position:relative}.outcomes-band li:before{content:"✓";color:#8fd3cc;font-weight:800;position:absolute;left:0}.section-block{max-width:var(--content);margin:0 auto;padding:112px 24px;scroll-margin-top:78px}.section-heading{grid-template-columns:minmax(0,1.25fr) minmax(280px,.75fr);align-items:end;gap:54px;margin-bottom:52px;display:grid}.section-heading>p,.heading-actions>p{color:var(--ink-soft);margin-bottom:4px;font-size:1.02rem}.compact-heading{margin-bottom:34px}.teacher-note{border-left:4px solid var(--orange);background:var(--orange-soft);color:#56311f;grid-template-columns:auto 1fr;gap:18px;margin:-18px 0 38px;padding:18px 20px;display:grid}.teacher-note strong{white-space:nowrap}.concept-grid{grid-template-columns:repeat(3,1fr);gap:28px;display:grid}.concept-grid article{border-top:1px solid var(--ink);background:#ffffff52;flex-direction:column;min-height:310px;padding:32px;display:flex}.concept-number{color:var(--orange);letter-spacing:.12em;margin-bottom:auto;font-size:.76rem;font-weight:800}.concept-grid h3{margin-top:58px;font-family:Georgia,serif;font-size:1.8rem;font-weight:500}.concept-grid p{color:var(--ink-soft)}.concept-grid .concept-test,.concept-grid .formula-inline{border-top:1px solid var(--line);color:var(--teal-dark);margin-top:auto;margin-bottom:0;padding-top:18px;font-weight:750}.route-demo{border:1px solid var(--line);border-radius:var(--radius-lg);background:var(--surface);margin-top:30px;padding:30px;box-shadow:0 12px 35px #22313b12}.route-controls,.lab-controls{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;display:grid}.range-control{display:block}.range-control>span{color:var(--ink-soft);justify-content:space-between;gap:14px;margin-bottom:8px;font-size:.84rem;font-weight:700;display:flex}.range-control strong{color:var(--ink);white-space:nowrap}input[type=range]{width:100%;accent-color:var(--teal)}.range-control input[type=range]{min-height:44px}.route-line{width:100%;margin:18px 0 8px;overflow:visible}.route-axis,.route-tick{stroke:#98a6ab;stroke-width:2px}.route-tick-label,.route-leg-label{fill:var(--ink-soft);font-size:12px}.route-leg-one,.route-leg-two{stroke-width:4px}.route-leg-one{stroke:var(--teal)}.route-leg-two{stroke:var(--orange)}#route-arrow-one path{fill:var(--teal)}#route-arrow-two path{fill:var(--orange)}.route-start{fill:var(--ink)}.route-turn{fill:var(--teal)}.route-finish{fill:var(--orange);stroke:var(--surface);stroke-width:3px}.comparison-values{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;display:grid}.comparison-values>div{border-radius:var(--radius-sm);background:var(--paper);grid-template-columns:1fr auto;gap:3px 16px;padding:18px 20px;display:grid}.comparison-values span{color:var(--ink-soft);font-size:.82rem;font-weight:700}.comparison-values strong{grid-area:1/2/3;align-self:center;font-family:Georgia,serif;font-size:1.65rem;font-weight:500}.comparison-values small{color:var(--teal-dark)}.teacher-inline{border-radius:var(--radius-sm);background:var(--orange-soft);color:#623820;margin:18px 0 0;padding:14px 16px}.definition-pair{grid-template-columns:repeat(2,minmax(0,1fr));gap:32px;margin-top:70px;display:grid}.definition-pair>article{border-radius:var(--radius-md);background:var(--paper-deep);padding:32px}.definition-pair h3{font-family:Georgia,serif;font-size:2rem;font-weight:500}.definition-pair>article>p:last-child{color:var(--ink-soft);margin-bottom:0}.equation-row{background:var(--line);border-radius:10px;gap:1px;margin:22px 0;display:grid;overflow:hidden}.equation-row p{background:var(--surface);justify-content:space-between;gap:20px;margin:0;padding:14px 16px;display:flex}.equation-row span{color:var(--ink-soft);font-size:.82rem;font-weight:700}.equation-row strong{color:var(--teal-dark)}.kinematics-intro{grid-template-columns:minmax(0,1.12fr) minmax(320px,.88fr);gap:32px;display:grid}.plain-language-card,.kinematics-boundary{border-radius:var(--radius-lg);padding:clamp(28px,4vw,44px)}.plain-language-card{background:var(--ink);color:#fff}.plain-language-label{color:#8fd3cc;letter-spacing:.14em;text-transform:uppercase;margin-bottom:12px;font-size:.76rem;font-weight:800}.plain-language-card h3{max-width:640px;font-family:Georgia,serif;font-size:clamp(1.8rem,3vw,2.6rem);font-weight:500}.question-list{border-top:1px solid #ffffff2e;margin:30px 0 0;padding:0;list-style:none}.question-list li{border-bottom:1px solid #ffffff2e;justify-content:space-between;gap:20px;padding:15px 0;display:flex}.question-list span{color:#a9d8d4;white-space:nowrap}.kinematics-boundary{background:var(--orange-soft);flex-direction:column;justify-content:center;display:flex}.kinematics-boundary>div{border-bottom:1px solid #56311f2e;flex-direction:column;padding:18px 0;display:flex}.kinematics-boundary span{color:#7b4225;letter-spacing:.1em;text-transform:uppercase;margin-bottom:5px;font-size:.75rem;font-weight:800}.kinematics-boundary strong{font-family:Georgia,serif;font-size:1.3rem;font-weight:500}.kinematics-boundary>p{color:#6b3a22;margin:22px 0 0}.motion-language{grid-template-columns:1fr auto 1fr auto 1fr;align-items:stretch;gap:14px;margin-top:36px;display:grid}.motion-language article{border-top:2px solid var(--teal);background:#ffffff61;padding:26px}.motion-language article>span{color:var(--orange);font-size:.74rem;font-weight:800}.motion-language h3{margin-top:32px;font-family:Georgia,serif;font-size:1.55rem;font-weight:500}.motion-language p{color:var(--ink-soft);margin-bottom:0}.language-arrow{color:var(--teal-dark);letter-spacing:.04em;text-transform:uppercase;align-self:center;font-size:.72rem;font-weight:800}.self-study-strip{border:1px solid var(--line);border-radius:var(--radius-md);background:var(--surface);grid-template-columns:minmax(240px,.72fr) minmax(0,1.28fr);gap:32px;margin-top:36px;padding:30px;display:grid}.self-study-strip h3{margin-bottom:0;font-family:Georgia,serif;font-size:1.65rem;font-weight:500}.self-study-strip ol{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px 24px;margin:0;padding:0;list-style:none;display:grid}.self-study-strip li{color:var(--ink-soft);gap:10px;display:flex}.self-study-strip li span{color:var(--orange);font-weight:800}.quick-check{border-top:1px solid var(--ink);border-bottom:1px solid var(--line-dark);margin-top:28px}.quick-check summary{cursor:pointer;padding:20px 48px 20px 4px;font-weight:800;list-style:none;position:relative}.quick-check summary::-webkit-details-marker{display:none}.quick-check summary:after{content:"+";font-family:Georgia,serif;font-size:2rem;font-weight:500;position:absolute;top:10px;right:8px}.quick-check[open] summary:after{content:"−"}.quick-check>div{max-width:850px;color:var(--ink-soft);padding:0 4px 20px}.quick-check>div p:last-child{margin-bottom:0}.foundation-summary{border-radius:var(--radius-md);background:var(--paper-deep);grid-template-columns:.7fr 1fr .8fr;align-items:center;gap:30px;margin-top:64px;padding:32px;display:grid}.foundation-summary h3{margin-bottom:0;font-family:Georgia,serif;font-size:1.8rem;font-weight:500}.foundation-summary .equation-row{margin:0}.foundation-summary>p{color:var(--ink-soft);margin-bottom:0}.math-bridge{max-width:none;padding-left:max(24px, calc((100vw - var(--content)) / 2));padding-right:max(24px, calc((100vw - var(--content)) / 2));background:#e8f0ed}.math-bridge .section-heading h2{max-width:760px;font-size:clamp(2.45rem,4.2vw,3.9rem)}.notation-contrast{grid-template-columns:minmax(0,1fr) auto minmax(0,1fr);align-items:stretch;gap:20px;display:grid}.notation-contrast article{border-radius:var(--radius-md);background:var(--surface);grid-template-columns:auto 1fr;gap:22px;padding:30px;display:grid}.notation-symbol{background:var(--teal-soft);width:54px;height:54px;color:var(--teal-dark);border-radius:50%;place-items:center;font-family:Georgia,serif;font-size:2rem;font-style:italic;display:grid}.notation-contrast h3{font-family:Georgia,serif;font-size:1.65rem;font-weight:500}.notation-contrast article p:last-child{color:var(--ink-soft);margin-bottom:0}.contrast-arrow{max-width:105px;color:var(--teal-dark);text-align:center;text-transform:uppercase;align-self:center;font-size:.72rem;font-weight:800}.notation-caution{border-left:4px solid var(--orange);background:var(--orange-soft);color:#61371f;margin:24px 0 0;padding:16px 20px}.math-lab{border-radius:var(--radius-lg);background:var(--surface);grid-template-columns:minmax(300px,.82fr) minmax(0,1.18fr);align-items:center;gap:clamp(30px,5vw,60px);margin:70px 0;padding:clamp(24px,4vw,46px);display:grid;box-shadow:0 18px 52px #1c34391a}.math-lab-copy h3{font-family:Georgia,serif;font-size:clamp(2rem,3.4vw,3.15rem);font-weight:500}.math-lab-copy>p:not(.eyebrow):not(.lab-reading){color:var(--ink-soft)}.formula-stack{border-radius:var(--radius-sm);background:var(--line);gap:1px;margin:26px 0;display:grid;overflow:hidden}.formula-stack p{background:var(--paper);justify-content:space-between;align-items:baseline;gap:18px;margin:0;padding:14px 16px;display:flex}.formula-stack span{color:var(--ink-soft);text-transform:uppercase;font-size:.77rem;font-weight:800}.formula-stack strong{color:var(--teal-dark);text-align:right;font-family:Georgia,serif;font-size:1.12rem;font-weight:500}.math-slider{margin-top:30px;display:block}.math-slider>span{justify-content:space-between;gap:16px;margin-bottom:10px;font-weight:800;display:flex}.math-slider strong{color:var(--teal-dark);white-space:nowrap}.math-slider input{min-height:44px}.lab-reading{border-left:3px solid var(--teal);background:var(--teal-soft);color:var(--teal-dark);margin:12px 0 0;padding:14px 16px}.math-figure{min-width:0;margin:0}.math-figure figcaption{flex-direction:column;margin-bottom:12px;display:flex}.math-figure figcaption strong{font-family:Georgia,serif;font-size:1.3rem;font-weight:500}.math-figure figcaption span{color:var(--ink-soft);font-size:.82rem}.math-figure svg{width:100%;overflow:visible}.math-gridline{stroke:#dedbd2;stroke-width:1px}.math-axis{stroke:var(--ink);stroke-width:2px}.math-tick,.axis-title,.plot-label,.delta-label,.curve-label,.area-total-label{fill:var(--ink-soft);font-family:Aptos,Segoe UI,Arial,sans-serif;font-size:13px}.axis-title,.curve-label{font-weight:800}.position-curve{fill:none;stroke:var(--teal);stroke-width:4px}.secant-line{stroke:var(--blue);stroke-width:4px}.tangent-line{stroke:var(--orange);stroke-width:4px;stroke-dasharray:11 7}.delta-guide{stroke:#6e7f86;stroke-width:1.5px;stroke-dasharray:5 4}.point-primary{fill:var(--orange);stroke:var(--surface);stroke-width:3px}.point-secondary{fill:var(--blue);stroke:var(--surface);stroke-width:3px}.delta-label{font-weight:800}.line-key{color:var(--ink-soft);flex-wrap:wrap;justify-content:center;gap:18px;font-size:.8rem;display:flex}.line-key span{align-items:center;gap:7px;display:inline-flex}.line-key i{border-top:3px solid;width:28px;height:0;display:inline-block}.secant-swatch{border-color:var(--blue)!important}.tangent-swatch{border-color:var(--orange)!important;border-top-style:dashed!important}.exact-area{fill:#d9642d26}.area-slice{fill:#0f766e38;stroke:var(--teal-dark);stroke-width:1.4px}.velocity-area-line{stroke:var(--orange);stroke-width:4px}.area-total-label{fill:var(--teal-dark);font-weight:800}.calculus-chain{grid-template-columns:minmax(0,.9fr) minmax(0,1.1fr);gap:48px;margin-top:70px;display:grid}.calculus-chain>*,.chain-formula,.derivative-examples{min-width:0}.chain-copy h3,.reverse-chain h3,.signed-area-grid h3{font-family:Georgia,serif;font-size:2.15rem;font-weight:500}.chain-copy>p:not(.eyebrow),.reverse-chain>div>p:not(.eyebrow){color:var(--ink-soft)}.chain-formula{grid-template-columns:1fr auto 1.35fr auto 1.25fr;align-items:center;gap:10px;margin-top:28px;display:grid}.chain-formula span{border-radius:var(--radius-sm);background:var(--surface);min-height:94px;color:var(--teal-dark);text-align:center;flex-direction:column;justify-content:center;align-items:center;padding:16px;font-family:Georgia,serif;font-size:1.2rem;display:flex}.chain-formula small{color:var(--ink-soft);margin-top:5px;font-family:Aptos,Segoe UI,Arial,sans-serif;font-size:.72rem}.chain-formula b{color:var(--teal-dark);text-align:center;text-transform:uppercase;font-size:.66rem}.derivative-examples{border-radius:var(--radius-md);background:var(--surface);padding:30px}.table-wrap{width:100%;overflow-x:auto}.derivative-examples table,.equation-map table{border-collapse:collapse;width:100%}.derivative-examples th,.derivative-examples td,.equation-map th,.equation-map td{border-bottom:1px solid var(--line);text-align:left;vertical-align:top;padding:13px 12px}.derivative-examples th,.equation-map th{color:var(--ink-soft);letter-spacing:.04em;text-transform:uppercase;font-size:.73rem}.derivative-examples td:first-child,.derivative-examples td:nth-child(2),.derivative-examples td:nth-child(3),.equation-map td:first-child,.equation-map td:nth-child(2){color:var(--teal-dark);white-space:nowrap;font-family:Georgia,serif}.units-note{color:var(--ink-soft);margin:16px 0 0;font-size:.82rem}.math-check{margin-bottom:20px}.signed-area-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:28px;display:grid}.signed-area-grid article{border-top:2px solid var(--teal);background:var(--surface);padding:32px}.signed-area-grid p,.signed-area-grid li{color:var(--ink-soft)}.signed-area-grid li+li{margin-top:7px}.signed-area-grid .display-formula{color:var(--teal-dark);font-family:Georgia,serif;font-size:1.55rem;font-weight:500}.reverse-chain{border-radius:var(--radius-md);background:var(--ink);color:#fff;grid-template-columns:minmax(0,.75fr) minmax(0,1.25fr);gap:40px;margin-top:36px;padding:34px;display:grid}.reverse-chain .eyebrow{color:#8fd3cc}.reverse-chain>div>p:not(.eyebrow){color:#c7d5d9}.initial-condition-formulas{gap:12px;display:grid}.initial-condition-formulas p{border-radius:var(--radius-sm);border:1px solid #ffffff2b;flex-direction:column;margin:0;padding:15px 18px;display:flex}.initial-condition-formulas span{color:#8fd3cc;text-transform:uppercase;margin-bottom:5px;font-size:.73rem;font-weight:800}.initial-condition-formulas strong{font-family:Georgia,serif;font-size:1.12rem;font-weight:500}.initial-condition-formulas small{color:#aebfc4}.graph-section{max-width:1320px;padding-top:58px;padding-bottom:58px}.lab-shell{color:#fff;background:#102d35;border-radius:34px;padding:clamp(24px,4vw,52px);box-shadow:0 26px 70px #09202838}.lab-shell .eyebrow{color:#7ed2c8}.lab-shell .section-heading>p{color:#bfd1d6}.lab-shell .teacher-note{color:#ffe7d7;background:#f9dfcf1f;margin-top:0}.lab-controls{grid-template-columns:repeat(5,minmax(0,1fr));align-items:end}.select-control{gap:7px;display:grid}.select-control span,.lab-shell .range-control>span{color:#c8d9dd}.lab-shell .range-control strong{color:#fff}.select-control span{font-size:.84rem;font-weight:700}.select-control select{color:#fff;background:#173943;border:1px solid #ffffff40;border-radius:10px;width:100%;min-height:44px;padding:9px 34px 9px 12px}.lab-shell input[type=range]{accent-color:#70cfc4}.motion-stage{border-radius:var(--radius-md);color:var(--ink);background:#f7f5ef;margin-top:30px;padding:20px 24px 10px}.stage-topline{justify-content:space-between;align-items:flex-start;gap:20px;display:flex}.stage-topline>div{flex-direction:column;display:flex}.stage-kicker{color:var(--teal);letter-spacing:.12em;text-transform:uppercase;margin-bottom:4px;font-size:.72rem;font-weight:800}.stage-topline strong{max-width:780px;font-size:.96rem}.time-chip{background:var(--ink);color:#fff;white-space:nowrap;border-radius:999px;padding:6px 10px;font-family:Cascadia Mono,Consolas,monospace;font-size:.8rem}.number-line{width:100%;display:block}.track-axis{stroke:#82939a;stroke-width:2px}.track-tick{stroke:#82939a;stroke-width:1.5px}.track-tick-label,.track-axis-label,.track-vector-label{fill:var(--ink-soft);font-size:12px}.trail-dot{fill:#bac5c8;opacity:.3}.trail-dot.trail-seen{fill:var(--teal);opacity:.85}.cart rect{fill:var(--ink)}.cart circle{fill:var(--surface);stroke:var(--ink);stroke-width:3px}.track-vector{stroke-width:4px}.track-arrowhead.velocity-vector,.track-vector.velocity-vector{fill:var(--orange);stroke:var(--orange)}.track-arrowhead.acceleration-vector,.track-vector.acceleration-vector{fill:var(--blue);stroke:var(--blue)}.track-vector-label.velocity-vector{fill:#a34018;font-weight:800}.track-vector-label.acceleration-vector{fill:#3247a8;font-weight:800}.playback-row{margin:16px 0}.lab-shell .button{color:#fff;border-color:#ffffff57}.lab-shell .button-primary{color:var(--ink);background:#fff;border-color:#fff}.time-scrubber{flex:1;align-items:center;min-width:220px;display:flex}.live-values{border-radius:var(--radius-sm);border:1px solid #ffffff29;grid-template-columns:repeat(4,minmax(0,1fr));margin:16px 0 24px;display:grid;overflow:hidden}.live-values>div{flex-direction:column;padding:14px 16px;display:flex}.live-values>div+div{border-left:1px solid #ffffff29}.live-values span{color:#aac2c8;letter-spacing:.08em;text-transform:uppercase;font-size:.72rem;font-weight:700}.live-values strong{margin-top:3px;font-family:Cascadia Mono,Consolas,monospace;font-size:1.05rem}.graph-grid{grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;display:grid}.motion-graph{border-radius:var(--radius-sm);min-width:0;color:var(--ink);background:#f9f8f3;margin:0;padding:16px 12px 5px}.motion-graph figcaption{flex-direction:column;padding:0 8px;display:flex}.motion-graph figcaption strong{font-size:.95rem}.motion-graph figcaption span{color:var(--ink-soft);font-size:.72rem}.motion-graph svg{width:100%;display:block}.chart-grid{stroke:#dce1df;stroke-width:1px}.chart-axis{stroke:#6f7f85;stroke-width:1.5px}.chart-zero{stroke:#87979c;stroke-width:1.4px}.chart-line{fill:none;stroke-width:3.2px;stroke-linecap:round;stroke-linejoin:round}.chart-line.position-series{stroke:var(--teal)}.chart-line.velocity-series{stroke:var(--orange)}.chart-line.acceleration-series{stroke:var(--blue)}.chart-area{stroke:none;opacity:.16}.chart-area.velocity-series{fill:var(--orange)}.chart-area.acceleration-series{fill:var(--blue)}.chart-area.positive-area{opacity:.14}.chart-area.negative-area{opacity:.28}.chart-area-sign{fill:var(--ink);font-size:15px;font-weight:800}.chart-point.position-series{fill:var(--teal)}.chart-point.velocity-series{fill:var(--orange)}.chart-point.acceleration-series{fill:var(--blue)}.chart-point{stroke:#fff;stroke-width:2px}.chart-tangent{stroke:var(--ink);stroke-width:2px;stroke-dasharray:5 4}.chart-cursor{stroke:#65777d;stroke-width:1.2px;stroke-dasharray:3 4}.chart-tick,.chart-axis-label{fill:#52666e;font-size:11px}.chart-axis-label{font-weight:700}.turning-marker circle{fill:var(--yellow);stroke:var(--ink);stroke-width:2px}.turning-marker text{fill:var(--ink);font-size:10px;font-weight:800}.graph-reading-rule{color:#cbdadd;text-align:center;margin:20px 0 0}.equation-studio{max-width:none;padding-left:max(24px, calc((100vw - var(--content)) / 2));padding-right:max(24px, calc((100vw - var(--content)) / 2));background:radial-gradient(circle at 92% 8%,#0f766e21,#0000 28%),#e6efec}.equation-studio>.section-heading,.studio-shell{width:min(100%, var(--content));margin-left:auto;margin-right:auto}.equation-studio .section-heading h2{max-width:830px;font-size:clamp(2.4rem,4vw,3.75rem)}.studio-shell{background:var(--surface);box-shadow:var(--shadow);border:1px solid #152b3a24;border-radius:32px;padding:clamp(24px,4vw,48px)}.studio-toolbar{border-bottom:1px solid var(--line);grid-template-columns:minmax(220px,.72fr) minmax(240px,1fr) minmax(250px,1fr);align-items:center;gap:24px;padding-bottom:28px;display:grid}.studio-preset-control{gap:7px;min-width:0;display:grid}.studio-preset-control span,.studio-preset-description span{color:var(--ink-soft);letter-spacing:.08em;text-transform:uppercase;font-size:.76rem;font-weight:800}.studio-preset-control select{border:1px solid var(--line-dark);width:100%;min-height:46px;color:var(--ink);background:#fff;border-radius:10px;padding:9px 34px 9px 12px}.studio-preset-description{border-left:4px solid var(--teal);flex-direction:column;min-width:0;padding-left:20px;display:flex}.studio-preset-description strong{margin-top:5px;line-height:1.35}.studio-condition{border-left:4px solid var(--orange);color:var(--ink-soft);margin:0;padding-left:20px;font-size:.9rem}.studio-condition strong{color:var(--ink)}.studio-condition span{margin-top:5px;display:block}.studio-workspace{grid-template-columns:minmax(300px,.82fr) minmax(0,1.18fr);gap:18px;margin-top:28px;display:grid}.studio-workspace>*{min-width:0}.studio-controls{border:1px solid var(--line);border-radius:var(--radius-md);background:var(--paper);margin:0;padding:clamp(22px,3vw,32px)}.studio-controls legend{color:var(--teal-dark);letter-spacing:.08em;text-transform:uppercase;padding:0 9px;font-size:.82rem;font-weight:800}.studio-predict{color:var(--ink-soft);margin-bottom:24px;font-size:.9rem}.studio-control-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:25px 20px;display:grid}.studio-equations{border-radius:var(--radius-md);background:var(--ink);color:#fff;padding:clamp(24px,3.5vw,38px)}.studio-step-label{color:var(--teal-dark);letter-spacing:.1em;text-transform:uppercase;margin-bottom:7px;font-size:.76rem;font-weight:800}.studio-equations .studio-step-label{color:#83d5cb}.studio-equations h3,.studio-graph-intro h3{margin-bottom:16px;font-family:Georgia,serif;font-size:clamp(1.55rem,2.4vw,2.1rem);font-weight:500}.studio-general-formula{color:#bed4d8;overflow-wrap:anywhere;border-bottom:1px solid #ffffff2b;padding-bottom:18px;font-family:Cascadia Mono,Consolas,monospace}.studio-equation-stack{border-radius:var(--radius-sm);background:#ffffff26;border:1px solid #ffffff29;gap:1px;display:grid;overflow:hidden}.studio-equation-stack p{background:#1b3948;grid-template-columns:minmax(115px,.7fr) minmax(0,1.3fr);align-items:baseline;gap:14px;margin:0;padding:13px 15px;display:grid}.studio-equation-stack span{color:#b8cdd2;font-size:.74rem}.studio-equation-stack strong{overflow-wrap:anywhere;font-family:Cascadia Mono,Consolas,monospace;font-size:1.02rem}.coefficient-key{grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:18px 0 0;display:grid}.coefficient-key div{min-width:0}.coefficient-key dt{color:#83d5cb;font-family:Georgia,serif;font-size:1.15rem;font-weight:700}.coefficient-key dd{color:#bed0d4;margin:2px 0 0;font-size:.76rem;line-height:1.4}.studio-change-note{border-left:4px solid var(--yellow);color:#eff6f6;background:#f0c24d1a;margin:20px 0 0;padding:14px 16px;font-size:.9rem}.studio-graph-intro{grid-template-columns:minmax(0,1fr) minmax(300px,.65fr);align-items:end;gap:34px;margin-top:38px;display:grid}.studio-scale-note{color:var(--ink-soft);grid-column:1/-1;margin:-12px 0 0;font-size:.82rem}.studio-scale-note strong{color:var(--ink)}.studio-time-control{min-width:0;display:block}.studio-time-control input[type=range]{min-height:44px}.studio-time-control>span{color:var(--ink-soft);justify-content:space-between;gap:16px;margin-bottom:8px;font-size:.86rem;font-weight:700;display:flex}.studio-time-control strong{color:var(--ink);white-space:nowrap}.studio-readout{border:1px solid var(--line);border-radius:var(--radius-sm);background:var(--paper-deep);grid-template-columns:repeat(3,minmax(0,1fr));margin:20px 0 14px;display:grid;overflow:hidden}.studio-readout div{justify-content:space-between;align-items:baseline;gap:12px;padding:13px 16px;display:flex}.studio-readout div+div{border-left:1px solid var(--line)}.studio-readout dt{color:var(--ink-soft);text-transform:uppercase;font-size:.76rem;font-weight:800}.studio-readout dd{white-space:nowrap;margin:0;font-family:Cascadia Mono,Consolas,monospace;font-weight:800}.studio-graphs .motion-graph{border:1px solid var(--line);background:#fff;grid-template-columns:minmax(180px,220px) minmax(0,1fr);align-items:center;display:grid}.studio-graphs{grid-template-columns:minmax(0,1fr);gap:16px}.studio-interpretation,.studio-cautions{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;display:grid}.studio-interpretation{margin-top:16px}.studio-interpretation p{border-left:4px solid var(--teal);background:var(--teal-soft);margin:0;padding:15px 17px}.studio-interpretation p+p{border-left-color:var(--orange);background:var(--orange-soft)}.studio-interpretation .studio-area-reading{border-left-color:var(--blue);background:var(--blue-soft);grid-column:1/-1}.studio-cautions{border-top:1px solid var(--line);margin-top:22px;padding-top:20px}.studio-cautions p{color:var(--ink-soft);margin:0;font-size:.88rem}.studio-cautions strong{color:var(--ink)}.studio-check{margin-bottom:0}.signs{padding-top:86px}.sign-grid{border-radius:var(--radius-md);background:var(--line);grid-template-columns:repeat(4,minmax(0,1fr));gap:1px;display:grid;overflow:hidden}.sign-grid article{background:var(--surface);flex-direction:column;min-height:250px;padding:24px;display:flex}.sign-grid article>span{color:var(--ink-soft);font-family:Cascadia Mono,Consolas,monospace;font-size:.85rem}.sign-grid strong{margin-top:16px;font-size:1rem}.sign-arrows{color:var(--teal);letter-spacing:.08em;margin-top:auto;font-family:Georgia,serif;font-size:3rem}.key-rule{text-align:center;margin:22px 0 0}.equations-section{max-width:none;padding-left:max(24px, calc((100vw - var(--content)) / 2));padding-right:max(24px, calc((100vw - var(--content)) / 2));background:var(--paper-deep)}.equations-section .section-heading h2{max-width:790px;font-size:clamp(2.45rem,4vw,3.75rem)}.condition-banner{border-left:4px solid var(--orange);background:var(--surface);gap:18px;margin-bottom:36px;padding:18px 22px;display:flex}.condition-banner strong{white-space:nowrap}.equation-goal{border-radius:var(--radius-lg);background:var(--ink);color:#fff;grid-template-columns:minmax(0,.92fr) minmax(360px,1.08fr);align-items:center;gap:42px;margin-bottom:30px;padding:clamp(26px,4vw,42px);display:grid}.equation-goal .eyebrow{color:#8fd3cc}.equation-goal h3{font-family:Georgia,serif;font-size:clamp(2rem,3.2vw,2.9rem);font-weight:500}.equation-goal>div>p:last-child{color:#c6d5d9;margin-bottom:0}.symbol-key{border-radius:var(--radius-sm);background:#ffffff29;border:1px solid #ffffff29;grid-template-columns:repeat(2,minmax(0,1fr));gap:1px;margin:0;display:grid;overflow:hidden}.symbol-key div{background:#1b3948;grid-template-columns:auto 1fr;align-items:center;gap:12px;min-height:74px;padding:13px 15px;display:grid}.symbol-key div:last-child{grid-column:1/-1}.symbol-key dt{color:#8fd3cc;font-family:Georgia,serif;font-size:1.45rem;font-style:italic}.symbol-key dd{color:#d7e2e5;margin:0;font-size:.84rem}.equation-targets{grid-template-columns:repeat(2,minmax(0,1fr));gap:24px;margin-bottom:44px;display:grid}.equation-targets article{border-top:2px solid var(--teal);background:var(--surface);grid-template-columns:1fr auto;align-items:center;gap:5px 20px;padding:26px 30px;display:grid}.equation-targets span{color:var(--ink-soft);letter-spacing:.08em;text-transform:uppercase;font-size:.75rem;font-weight:800}.equation-targets strong{color:var(--teal-dark);white-space:nowrap;grid-area:1/2/3;font-family:Georgia,serif;font-size:clamp(1.45rem,2.5vw,2rem);font-weight:500}.equation-targets p{color:var(--ink-soft);margin:0}.derivation-layout{grid-template-columns:minmax(0,.95fr) minmax(0,1.05fr);align-items:stretch;gap:42px;display:grid}.derivation-walkthrough{gap:16px;display:grid}.derivation-walkthrough article{border-radius:var(--radius-md);background:var(--surface);grid-template-columns:42px 1fr;gap:16px;padding:26px;display:grid}.derivation-walkthrough article>span{background:var(--teal-soft);width:36px;height:36px;color:var(--teal-dark);border-radius:50%;place-items:center;font-weight:800;display:grid}.derivation-walkthrough h3{margin-bottom:9px;font-size:1.12rem}.derivation-walkthrough p{color:var(--ink-soft);margin:0 0 8px}.derivation-walkthrough .derivation-equation,.derivation-walkthrough .derivation-result{color:var(--teal-dark);font-family:Georgia,serif;font-size:1.17rem}.derivation-walkthrough .derivation-result{border-left:3px solid var(--orange);background:var(--orange-soft);margin-top:10px;padding:10px 14px;font-size:1.35rem;font-weight:700}.derivation-walkthrough .plain-translation{margin:12px 0 0;font-size:.88rem}.guided-area-figure{border-radius:var(--radius-md);background:var(--surface);flex-direction:column;justify-content:flex-start;align-self:start;margin:0;padding:clamp(22px,3vw,34px);display:flex}.guided-area-figure figcaption{flex-direction:column;display:flex}.guided-area-figure figcaption strong{font-family:Georgia,serif;font-size:1.4rem;font-weight:500}.guided-area-figure figcaption span{color:var(--ink-soft);font-size:.83rem}.guided-area-figure svg{width:100%;margin-top:12px;overflow:visible}.trap-axis{stroke:var(--ink);stroke-width:2px}.trap-guide,.rise-guide{stroke:#75878e;stroke-width:1.4px;stroke-dasharray:5 4}.trap-line{stroke:var(--ink);stroke-width:4px}.trap-rectangle{fill:#0f766e9e}.trap-triangle{fill:#d9642db8}.guided-area-figure text{fill:var(--ink-soft);font-family:Aptos,Segoe UI,Arial,sans-serif;font-size:14px}.guided-area-figure .trap-area-label{fill:#fff;font-size:15px;font-weight:800}.guided-area-figure .trap-small-label{fill:#fff;font-size:14px;font-weight:800}.guided-area-figure .trap-end-label{fill:var(--ink);font-family:Georgia,serif;font-size:17px;font-style:italic;font-weight:700}.guided-area-figure .trap-slope-label,.guided-area-figure .trap-rise-label{fill:var(--ink);font-size:13px;font-weight:800}.guided-area-figure .trap-axis-label{fill:var(--ink-soft);font-size:13px;font-weight:700}.figure-takeaway{border-left:3px solid var(--teal);background:var(--teal-soft);color:var(--teal-dark);margin:0;padding:13px 16px;font-weight:700}.equation-check{margin-top:34px}.equation-family{grid-template-columns:repeat(2,minmax(0,1fr));gap:28px;margin-top:42px;display:grid}.equation-family article{border-radius:var(--radius-md);background:var(--surface);padding:32px}.equation-family h3{font-family:Georgia,serif;font-size:2rem;font-weight:500}.equation-family article>p:not(.eyebrow):not(.family-steps):not(.family-result){color:var(--ink-soft)}.family-steps,.family-result{background:var(--paper);color:var(--teal-dark);margin:0;padding:10px 14px;font-family:Georgia,serif;font-size:1.12rem}.family-steps+.family-steps,.family-steps+.family-result{border-top:1px solid var(--line)}.family-result{color:var(--teal-dark);font-size:1.35rem;font-weight:700}.equation-family small{color:var(--ink-soft);margin-top:14px;display:block}.calculus-route{border-radius:var(--radius-md);background:var(--ink);color:#fff;margin-top:32px}.calculus-route summary{cursor:pointer;padding:22px 26px;font-weight:800}.calculus-route>div{padding:0 26px 26px}.calculus-route>div>p:not(.calculus-line){color:#c7d5d9}.calculus-line{border-radius:var(--radius-sm);color:#b2e5df;border:1px solid #ffffff29;padding:13px 16px;font-family:Georgia,serif;font-size:1.15rem}.equation-map{border-radius:var(--radius-md);background:var(--surface);margin-top:42px;padding:32px}.equation-map h3{font-family:Georgia,serif;font-size:2rem;font-weight:500}.problem-routine{border-radius:var(--radius-md);background:var(--surface);grid-template-columns:.66fr 1.34fr;gap:38px;margin-top:44px;padding:32px;display:grid}.problem-routine h3{font-family:Georgia,serif;font-size:2.1rem;font-weight:500}.problem-routine ol{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px 24px;margin:0;padding:0;list-style:none;display:grid}.problem-routine li{color:var(--ink-soft);gap:10px;display:flex}.problem-routine li span{color:var(--orange);font-weight:800}.example-list{border-top:1px solid var(--ink)}.example-list details{border-bottom:1px solid var(--line-dark)}.example-list summary{cursor:pointer;grid-template-columns:54px 1fr;align-items:center;padding:24px 4px;list-style:none;display:grid}.example-list summary::-webkit-details-marker{display:none}.example-list summary:after{content:"+";grid-column:3;font-family:Georgia,serif;font-size:2rem}.example-list details[open] summary:after{content:"−"}.example-list summary>span{color:var(--orange);font-size:.78rem;font-weight:800}.example-list summary div{flex-direction:column;display:flex}.example-list summary strong{font-family:Georgia,serif;font-size:1.45rem;font-weight:500}.example-list summary small{color:var(--ink-soft);margin-top:4px}.solution{max-width:850px;padding:0 58px 28px}.solution p{color:var(--ink-soft)}.solution .takeaway{border-left:3px solid var(--teal);background:var(--teal-soft);color:var(--teal-dark);margin-bottom:0;padding:12px 16px}.plane-motion{max-width:none;padding-left:max(24px, calc((100vw - var(--content)) / 2));padding-right:max(24px, calc((100vw - var(--content)) / 2));background:#e3efec}.plane-grid{grid-template-columns:repeat(3,minmax(0,1fr));gap:22px;display:grid}.plane-grid article{border-radius:var(--radius-md);background:var(--surface);padding:30px}.topic-label{color:var(--orange);letter-spacing:.1em;text-transform:uppercase;font-size:.72rem;font-weight:800}.plane-grid h3{margin-top:30px;font-family:Georgia,serif;font-size:1.8rem;font-weight:500}.plane-grid p{color:var(--ink-soft)}.formula-block{background:var(--paper);border-radius:10px;padding:15px 17px;font-family:Georgia,serif;font-size:1.08rem;line-height:1.7;color:var(--teal-dark)!important}.projectile-example{border-radius:var(--radius-md);background:var(--ink);color:#fff;grid-template-columns:.8fr 1.2fr;align-items:center;gap:42px;margin-top:24px;padding:30px;display:grid}.projectile-example .eyebrow{color:#8fd3cc}.projectile-example h3{font-family:Georgia,serif;font-size:2rem;font-weight:500}.projectile-example>div:first-child>p:last-child{color:#c5d5d9;margin-bottom:0}.projectile-results{border-radius:var(--radius-sm);background:#ffffff29;grid-template-columns:repeat(3,minmax(0,1fr));gap:1px;display:grid;overflow:hidden}.projectile-results p{background:#173944;flex-direction:column;margin:0;padding:18px;display:flex}.projectile-results span{color:#9fb9bf;text-transform:uppercase;font-size:.72rem;font-weight:700}.projectile-results strong{margin-top:8px;font-size:.92rem}.condition-note{color:var(--ink-soft);margin:18px 0 0}.heading-actions{flex-direction:column;align-items:flex-start;display:flex}.checks-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;display:grid}.check-card{border:1px solid var(--line);border-radius:var(--radius-md);background:var(--surface);min-width:0;margin:0;padding:24px}.check-card legend{width:100%;padding:0;font-weight:750;line-height:1.4}.check-card legend>span{color:var(--orange);letter-spacing:.1em;text-transform:uppercase;margin-bottom:8px;font-size:.72rem;display:block}.check-options{gap:8px;margin-top:20px;display:grid}.check-options label{border:1px solid var(--line);cursor:pointer;border-radius:9px;align-items:center;gap:10px;min-height:44px;padding:10px 12px;display:flex}.check-options label:has(input:checked){border-color:var(--teal);background:var(--teal-soft)}.check-options input{width:18px;height:18px;accent-color:var(--teal)}.check-actions{margin-top:18px}.hint,.feedback,.teacher-answer{border-radius:9px;margin:16px 0 0;padding:13px 15px}.hint{color:#5b4613;background:#fff4cc}.feedback{background:var(--teal-soft);color:var(--teal-dark)}.needs-review .feedback{background:var(--orange-soft);color:#65381f}.teacher-answer{border-left:3px solid var(--orange);color:#663a22;background:#f7ebe2;font-size:.9rem}.lesson-plan{padding-top:70px}.lesson-timeline{border-top:1px solid var(--ink);grid-template-columns:repeat(3,minmax(0,1fr));gap:0;display:grid}.lesson-timeline article{padding:28px}.lesson-timeline article+article{border-left:1px solid var(--line-dark)}.lesson-timeline article>span{color:var(--orange);letter-spacing:.08em;text-transform:uppercase;font-size:.76rem;font-weight:800}.lesson-timeline h3{margin-top:28px;font-family:Georgia,serif;font-size:1.9rem;font-weight:500}.lesson-timeline ul{color:var(--ink-soft);margin:0;padding-left:19px}.lesson-timeline li+li{margin-top:6px}.worksheet{max-width:none;padding-left:max(24px, calc((100vw - var(--content)) / 2));padding-right:max(24px, calc((100vw - var(--content)) / 2));background:var(--paper-deep)}.worksheet-toolbar{justify-content:flex-end;margin:-24px 0 26px}.worksheet-paper{max-width:980px;box-shadow:var(--shadow);background:#fff;border:1px solid #d5cec1;margin:0 auto;padding:clamp(26px,5vw,58px)}.worksheet-heading{border-bottom:2px solid var(--ink);justify-content:space-between;align-items:flex-end;gap:24px;padding-bottom:18px;display:flex}.worksheet-heading>div{flex-direction:column;display:flex}.worksheet-heading span{color:var(--teal);letter-spacing:.12em;text-transform:uppercase;font-size:.74rem;font-weight:800}.worksheet-heading strong{font-family:Georgia,serif;font-size:2rem;font-weight:500}.worksheet-heading p{margin:0;font-size:.84rem}.problem-list{margin:30px 0;padding-left:24px}.problem-list li{padding-left:8px}.problem-list li+li{margin-top:16px}.problem-list li::marker{color:var(--teal);font-weight:800}.sketch-area,.exit-ticket{border-top:1px solid var(--line);margin-top:30px;padding-top:22px}.blank-graphs{grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;display:grid}.blank-graph{aspect-ratio:1.4;border-left:2px solid var(--ink);border-bottom:2px solid var(--ink);background-image:linear-gradient(90deg,#152b3a1a 1px,#0000 1px),linear-gradient(#152b3a1a 1px,#0000 1px);background-size:20% 20%;position:relative}.blank-graph span{font-family:Georgia,serif;font-style:italic;position:absolute;top:3px;left:7px}.blank-graph small{font-family:Georgia,serif;font-style:italic;position:absolute;bottom:2px;right:4px}.writing-lines{background:repeating-linear-gradient(#0000 0 25px,#d7d2c7 25px 26px);min-height:80px}.answer-key{border:2px solid var(--teal);background:#eff8f6;margin-top:34px;padding:24px;display:none}.answer-key.screen-visible{display:block}.answer-key h3{font-family:Georgia,serif;font-size:1.8rem;font-weight:500}.answer-key li+li{margin-top:7px}footer{padding:50px max(24px, calc((100vw - var(--content)) / 2));background:var(--ink);color:#fff;grid-template-columns:1fr 1fr;gap:40px;display:grid}footer strong{font-family:Georgia,serif;font-size:1.45rem;font-weight:500}footer p{color:#b9cbd0;max-width:620px;margin:8px 0 0}.footer-chapters-link{color:#a9e3dc;margin-top:14px;font-weight:750;display:inline-block}.skip-link{z-index:100;background:var(--ink);color:#fff;border-radius:999px;padding:10px 14px;text-decoration:none;transition:transform .14s;position:fixed;top:10px;left:12px;transform:translateY(-160%)}.skip-link:focus{transform:translateY(0)}.chapters-page{background:radial-gradient(circle at 90% 7%, #0f766e1a, transparent 24%), var(--paper);min-height:100vh}.chapters-header{z-index:50;-webkit-backdrop-filter:blur(15px);backdrop-filter:blur(15px);background:#f7f4ecf0;border-bottom:1px solid #152b3a1f;position:sticky;top:0}.chapters-header-inner{width:min(100%, var(--content));justify-content:space-between;align-items:center;gap:24px;min-height:72px;margin:0 auto;padding:10px 24px;display:flex}.chapters-brand{align-items:center;gap:11px;min-width:0;text-decoration:none;display:inline-flex}.chapters-brand-mark{background:var(--ink);color:#fff;border-radius:50%;flex:none;place-items:center;width:44px;height:44px;font-family:Georgia,serif;font-size:.88rem;display:grid}.chapters-brand>span:last-child{flex-direction:column;min-width:0;line-height:1.05;display:flex}.chapters-brand strong{text-overflow:ellipsis;white-space:nowrap;overflow:hidden}.chapters-brand small{color:var(--ink-soft);letter-spacing:.07em;text-transform:uppercase;margin-top:5px;font-size:.72rem}.chapters-header nav{align-items:center;gap:20px;display:flex}.chapters-header nav>a:first-child{color:var(--ink-soft);font-size:.9rem;font-weight:750;text-decoration:none}.chapters-header nav>a:first-child:hover{color:var(--teal)}.chapters-hero{width:min(100%, var(--content));grid-template-columns:minmax(0,1.18fr) minmax(330px,.82fr);align-items:center;gap:clamp(42px,7vw,88px);margin:0 auto;padding:clamp(76px,9vw,126px) 24px clamp(64px,8vw,105px);display:grid}.chapters-hero h1{max-width:760px;margin-bottom:25px;font-size:clamp(3rem,6.4vw,5.7rem)}.chapters-hero-copy>p:not(.eyebrow){max-width:710px;color:var(--ink-soft);margin-bottom:32px;font-size:clamp(1.05rem,1.6vw,1.22rem)}.chapters-progress{border-radius:var(--radius-lg);background:var(--ink);color:#fff;padding:clamp(28px,4vw,42px);box-shadow:0 24px 65px #152b3a33}.chapters-progress .eyebrow{color:#87d4cb}.chapters-progress-value{align-items:baseline;gap:13px;margin:0;display:flex}.chapters-progress-value strong{font-family:Georgia,serif;font-size:clamp(3.5rem,7vw,5.4rem);font-weight:500;line-height:.95}.chapters-progress-value span{color:#c6d5d9}.chapters-progress-track{background:#ffffff24;border-radius:999px;height:8px;margin:26px 0 28px;overflow:hidden}.chapters-progress-track span{border-radius:inherit;background:var(--orange);width:4.55%;min-width:18px;height:100%;display:block}.chapters-current{border-top:1px solid #ffffff29;padding-top:22px}.chapters-current>span{color:#87d4cb;letter-spacing:.1em;text-transform:uppercase;font-size:.74rem;font-weight:800}.chapters-current strong{margin-top:6px;font-family:Georgia,serif;font-size:1.35rem;font-weight:500;display:block}.chapters-current p{color:#bdced2;margin:10px 0 0;font-size:.9rem}.chapters-category-nav{width:min(calc(100% - 48px), var(--content));border:1px solid var(--line-dark);border-radius:var(--radius-md);background:var(--surface);grid-template-columns:repeat(3,minmax(0,1fr));margin:0 auto;display:grid;overflow:hidden;box-shadow:0 12px 38px #21303c12}.chapters-category-nav a{justify-content:space-between;align-items:center;gap:14px;min-height:78px;padding:16px 22px;text-decoration:none;display:flex}.chapters-category-nav a+a{border-left:1px solid var(--line)}.chapters-category-nav a:hover{background:var(--teal-soft)}.chapters-category-nav strong{font-family:Georgia,serif;font-size:1.2rem;font-weight:500}.chapters-category-nav span{color:var(--ink-soft);white-space:nowrap;font-size:.78rem}.chapters-library{width:min(100%, var(--content));margin:0 auto;padding:clamp(86px,9vw,125px) 24px 125px}.chapters-library-heading,.chapters-group-heading{grid-template-columns:minmax(0,1.12fr) minmax(300px,.88fr);align-items:end;gap:56px;display:grid}.chapters-library-heading{margin-bottom:80px}.chapters-library-heading h2{font-size:clamp(2.8rem,5vw,4.5rem)}.chapters-library-heading>p,.chapters-group-heading>p{color:var(--ink-soft);margin:0}.chapters-group{scroll-margin-top:94px}.chapters-group+.chapters-group{border-top:1px solid var(--line-dark);margin-top:105px;padding-top:80px}.chapters-group-heading{margin-bottom:35px}.chapters-group-heading span{color:var(--orange);letter-spacing:.11em;text-transform:uppercase;font-size:.76rem;font-weight:800}.chapters-group-heading h2{margin-top:8px;font-size:clamp(2.2rem,4vw,3.45rem)}.chapters-grid{grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;display:grid}.chapters-card{border:1px solid var(--line);border-radius:var(--radius-md);min-width:0;min-height:255px;color:var(--ink);background:#fffdf8b8;border-top:4px solid #b6c1c3;flex-direction:column;padding:25px;display:flex}a.chapters-card{text-decoration:none;transition:transform .15s,box-shadow .15s,border-color .15s}a.chapters-card:hover{transform:translateY(-3px)}.chapters-card-ready{border-color:var(--teal-dark);border-top-color:var(--orange);background:var(--ink);color:#fff;box-shadow:0 22px 50px #152b3a2b}.chapters-card-ready:hover{border-color:var(--orange);box-shadow:0 26px 58px #152b3a38}.chapters-card-topline{justify-content:space-between;align-items:center;gap:10px;display:flex}.chapters-number{color:var(--orange);letter-spacing:.09em;text-transform:uppercase;font-size:.73rem;font-weight:850}.chapters-status{background:var(--paper-deep);color:var(--ink-soft);white-space:nowrap;border-radius:999px;padding:4px 8px;font-size:.68rem;font-weight:800}.chapters-status-ready{color:#a9e3dc;background:#87d4cb2e}.chapters-card h3{overflow-wrap:anywhere;margin:38px 0 12px;font-family:Georgia,serif;font-size:clamp(1.35rem,2vw,1.72rem);font-weight:500}.chapters-card>p{color:var(--ink-soft);margin-bottom:24px;font-size:.9rem}.chapters-card-ready>p{color:#c4d4d8}.chapters-card-footer{border-top:1px solid var(--line);color:var(--ink-soft);justify-content:space-between;align-items:center;gap:16px;margin-top:auto;padding-top:17px;font-size:.8rem;font-weight:800;display:flex}.chapters-card-ready .chapters-card-footer{color:#fff;border-top-color:#ffffff29}.chapters-card-ready .chapters-card-footer span:last-child{color:#87d4cb;font-family:Georgia,serif;font-size:1.5rem}.chapters-footer a{color:#a9e3dc;margin-top:14px;font-weight:750;display:inline-block}@media (width<=1080px){.site-header{grid-template-columns:auto 1fr}.site-header nav{display:none}.teacher-switch{justify-self:end}.hero{grid-template-columns:1fr .72fr;gap:34px}.lab-controls{grid-template-columns:repeat(3,minmax(0,1fr))}.graph-grid{grid-template-columns:1fr}.studio-toolbar{grid-template-columns:repeat(2,minmax(0,1fr))}.studio-condition{grid-column:1/-1}.motion-graph{grid-template-columns:220px minmax(0,1fr);align-items:center;display:grid}.sign-grid{grid-template-columns:repeat(2,1fr)}.calculus-chain{grid-template-columns:minmax(0,1fr)}.derivation-layout,.projectile-example,.plane-grid{grid-template-columns:1fr}.plane-grid article{grid-template-columns:.55fr 1.45fr;gap:0 28px;display:grid}.plane-grid article .topic-label,.plane-grid article h3{grid-column:1}.plane-grid article p{grid-column:2}.plane-grid h3{margin-top:22px}}@media (width<=960px){.studio-workspace{grid-template-columns:minmax(0,1fr)}}@media (width<=900px){.chapters-hero,.chapters-library-heading,.chapters-group-heading{grid-template-columns:minmax(0,1fr)}.chapters-progress{width:min(100%,620px)}.chapters-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.chapters-library-heading,.chapters-group-heading{align-items:start;gap:24px}}@media (width<=820px){h1{font-size:clamp(3rem,13vw,5.4rem)}.hero{grid-template-columns:1fr;min-height:auto;padding-top:72px}.hero-visual{width:min(480px,100%);margin:20px auto 0}.outcomes-band,.section-heading,.kinematics-intro,.self-study-strip,.foundation-summary,.notation-contrast,.math-lab,.calculus-chain,.signed-area-grid,.reverse-chain,.equation-goal,.equation-targets,.equation-family,.derivation-layout,.problem-routine,.projectile-example{grid-template-columns:minmax(0,1fr)}.motion-language{grid-template-columns:1fr}.language-arrow,.contrast-arrow{text-align:left;max-width:none;padding:2px 0}.chain-formula{grid-template-columns:1fr}.chain-formula b{padding:2px 0}.math-lab,.equation-goal{align-items:start}.studio-toolbar,.studio-workspace,.studio-graph-intro,.studio-interpretation,.studio-cautions{grid-template-columns:minmax(0,1fr)}.studio-condition{grid-column:auto}.studio-preset-description,.studio-condition{padding-top:4px;padding-bottom:4px}.outcomes-band ul,.concept-grid,.checks-grid,.lesson-timeline{grid-template-columns:1fr}.concept-grid article{min-height:235px}.concept-grid h3{margin-top:34px}.lab-controls{grid-template-columns:repeat(2,minmax(0,1fr))}.motion-graph,.studio-graphs .motion-graph{display:block}.problem-routine ol,.projectile-results{grid-template-columns:1fr}.plane-grid article{display:block}.lesson-timeline article+article{border-top:1px solid var(--line-dark);border-left:0}.worksheet-heading{flex-direction:column;align-items:flex-start}footer{grid-template-columns:1fr}}@media (width<=560px){body{font-size:15px}.site-header{min-height:64px;padding:10px 16px}.brand small{display:none}.brand-mark{width:38px;height:38px}.teacher-switch{font-size:.8rem}.chapters-header-inner{min-height:64px;padding:9px 16px}.chapters-brand-mark{width:40px;height:40px}.chapters-brand small,.chapters-header nav{display:none}h2,.math-bridge .section-heading h2,.equations-section .section-heading h2,.equation-studio .section-heading h2{font-size:clamp(2.15rem,11vw,3.2rem)}.hero{padding:58px 18px 70px}.chapters-hero{padding:66px 18px 72px}.chapters-hero h1{font-size:clamp(3rem,15vw,4.4rem)}.chapters-progress{padding:24px}.chapters-category-nav{grid-template-columns:minmax(0,1fr);width:calc(100% - 36px)}.chapters-category-nav a{min-height:64px}.chapters-category-nav a+a{border-top:1px solid var(--line);border-left:0}.chapters-library{padding:76px 18px 86px}.chapters-library-heading{margin-bottom:55px}.chapters-group+.chapters-group{margin-top:76px;padding-top:62px}.chapters-grid{grid-template-columns:minmax(0,1fr)}.chapters-card{min-height:230px;padding:22px}.hero-actions .button{width:100%}.lesson-meta{grid-template-columns:1fr}.lesson-meta>div+div{border-top:1px solid var(--line-dark);border-left:0;padding-left:0}.hero-orbit span{display:none}.outcomes-band,.section-block{padding:76px 18px}.outcomes-band ul{grid-template-columns:1fr}.section-heading{gap:22px;margin-bottom:36px}.teacher-note{grid-template-columns:1fr;gap:6px}.route-demo,.lab-shell,.studio-shell,.worksheet-paper,.math-lab,.plain-language-card,.kinematics-boundary,.equation-goal,.guided-area-figure{border-radius:18px;padding:20px}.question-list li,.formula-stack p,.math-slider>span{flex-direction:column;align-items:flex-start;gap:5px}.question-list span{white-space:normal}.self-study-strip,.foundation-summary,.derivative-examples,.signed-area-grid article,.reverse-chain,.equation-family article,.equation-map{padding:22px}.self-study-strip ol,.symbol-key{grid-template-columns:1fr}.symbol-key div:last-child{grid-column:auto}.equation-targets article{grid-template-columns:1fr}.equation-targets strong{grid-area:auto;margin:6px 0}.derivation-walkthrough article{grid-template-columns:34px 1fr;gap:10px;padding:20px}.initial-condition-formulas strong,.calculus-line{overflow-wrap:anywhere;font-size:1rem}.math-figure .math-tick{font-size:17px}.math-figure .axis-title,.math-figure .plot-label,.math-figure .delta-label,.math-figure .curve-label,.math-figure .area-total-label,.guided-area-figure text{font-size:20px}.guided-area-figure .trap-area-label,.guided-area-figure .trap-small-label{font-size:21px}.guided-area-figure .trap-end-label{font-size:22px}.guided-area-figure .trap-slope-label,.guided-area-figure .trap-rise-label,.guided-area-figure .trap-axis-label{font-size:18px}.route-controls,.lab-controls,.studio-control-grid,.coefficient-key,.studio-readout,.comparison-values,.live-values,.sign-grid,.blank-graphs{grid-template-columns:1fr}.live-values>div+div{border-top:1px solid #ffffff29;border-left:0}.studio-readout div+div{border-top:1px solid var(--line);border-left:0}.studio-equation-stack p{grid-template-columns:minmax(0,1fr);gap:4px}.studio-graphs .chart-tick,.studio-graphs .chart-axis-label{font-size:17px}.studio-graphs .turning-marker text{font-size:15px}.studio-time-control>span{flex-direction:column;align-items:flex-start;gap:3px}.stage-topline{flex-direction:column}.playback-row .button{flex:1}.time-scrubber{min-width:100%}.motion-stage{padding:16px 10px 6px}.number-line{min-height:178px}.condition-banner{flex-direction:column;gap:6px}.solution{padding-left:0;padding-right:0}.example-list summary{grid-template-columns:42px 1fr}.projectile-results{gap:1px}.worksheet-toolbar .button{width:100%}}@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,:before,:after{transition-duration:.01ms!important;animation-duration:.01ms!important;animation-iteration-count:1!important}}@media print{@page{size:A4;margin:14mm}body{color:#000;background:#fff;font-size:10.5pt}body *{visibility:hidden}.worksheet,.worksheet *{visibility:visible}.worksheet{background:#fff;width:100%;max-width:none;padding:0;position:absolute;inset:0}.worksheet>.section-heading,.worksheet-toolbar,.no-print{display:none!important}.worksheet-paper{max-width:none;box-shadow:none;border:0;padding:0}.worksheet-heading strong{font-size:20pt}.problem-list li{break-inside:avoid}.blank-graph{break-inside:avoid;min-height:42mm}.answer-key.screen-visible{display:none}body[data-print-mode=teacher] .answer-key{break-before:page;background:#fff;border-color:#000;display:block!important}body[data-print-mode=student] .answer-key{display:none!important}}
