:root{--paper:#f6f5ef;--card:#fffefa;--ink:#243b34;--muted:#65736b;--green:#285b4b;--soft:#e6eee4;--line:#dedfd5;--orange:#b15b33;--peach:#f4e1d1;--blue:#dbe8ef;--radius:20px;font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:var(--paper);font-size:16px;line-height:1.6}
*{box-sizing:border-box}body{margin:0}a{color:var(--green);text-underline-offset:4px}button,input,select{font:inherit}button,a,input,summary{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:default;opacity:.45}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible,select:focus-visible{outline:3px solid #a04b22;outline-offset:4px}button{color:inherit}button:active{transform:translateY(1px)}[hidden]{display:none!important}h1,h2,h3,p{margin-top:0}h2,h3{line-height:1.25}p{margin-bottom:1rem}strong{font-weight:700}em{font-family:Georgia,serif;font-weight:400}.skip-link{position:absolute;left:16px;top:-100px;background:white;padding:12px;z-index:100}.skip-link:focus{top:8px}.site-header{height:90px;max-width:1380px;margin:auto;padding:0 54px;border-bottom:1px solid 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@media(max-width:1000px){.page-shell{gap:28px;grid-template-columns:200px minmax(0,1fr);padding-left:25px;padding-right:25px}.site-header{padding:0 28px}.card{padding:25px}.video-card{gap:16px}.video-info h3{font-size:20px}}
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@media(max-width:380px){.page-shell{padding-left:14px;padding-right:14px}.site-header{padding:0 14px}.stage-badge{display:none}.card{padding:18px}.shape{width:22px;height:22px}.shapes{gap:5px}.radio-option{font-size:9px;padding:6px 7px}.reveal-options{gap:4px}.course-intro h1{font-size:34px}}
@media(prefers-reduced-motion:no-preference){.chip,.lesson-link{transition:background .18s,border-color .18s}.shape{animation:appear .25s ease-out}@keyframes appear{from{opacity:.4;transform:scale(.8)}to{opacity:1;transform:scale(1)}}}
@media print{.site-header,.sidebar,.course-intro,.section-links,.video-section,.explore-card,.lesson-bottom,.reveal-options,.about-section,.page-footer{display:none}.page-shell{display:block;padding:0}.card,.question{break-inside:avoid;border-color:#aaa}.answer-panel[hidden],.working[hidden]{display:none!important}body{background:white;color:black}}

/* Keep small labels readable and give the video room on every screen. */
:root{--muted:#56675b}
.question-number,.page-footer{color:#5e715c}
.part.warm,.length-bar.short{background:#a45c36}
.lesson-card .intro,.explanation{font-size:16px}
.question h4{font-size:15px}
.method ol,.explore-output{font-size:14px}
.video-card{grid-template-columns:1fr;gap:15px}
.video-info{order:-1}
.topic-nav{display:flex;gap:7px;margin:0 0 20px}
.topic-nav a{padding:7px 17px;border:1px solid #cdd6c7;border-radius:7px;font-size:12px;text-decoration:none}
.topic-nav a[aria-current=page]{background:#285b4b;color:#fff;border-color:#285b4b}
.video-info h3{font-size:24px}
.video-info p{font-size:13px;margin-bottom:5px}
.video-info .video-detail{font-size:11px;margin-top:8px}
.video-live-caption{font-size:15px;line-height:1.8;margin:0;padding:12px 16px;background:#edf2e8;border-radius:8px;min-height:75px}
@media(max-width:760px){.lesson-card .intro,.explanation,.question h4{font-size:15px}.method ol,.explore-output{font-size:14px}.radio-option{font-size:11px;min-height:42px}.video-live-caption{font-size:14px}}