:root{--paper:#f7f5ee;--ink:#1e2c2c;--muted:#5e6c68;--line:#d9ddd3;--red:#b84932;--teal:#386d70;--card:#fffefa;--mono:ui-monospace,SFMono-Regular,Consolas,monospace}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:30px}body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.75 -apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC",sans-serif}a{color:var(--teal);text-underline-offset:4px}a:hover{color:var(--red)}button,a,input,select,textarea{touch-action:manipulation}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid var(--red);outline-offset:4px}.skip{position:absolute;top:-100px;left:16px}.skip:focus{top:10px;background:white;z-index:99;padding:10px}.top{max-width:1360px;margin:auto;padding:25px 4%;display:flex;align-items:center;justify-content:space-between;gap:20px;border-bottom:1px solid 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@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
/* Activities: manipulable state first, explanation next. */
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.demo-visual{overflow-x:auto;overscroll-behavior-x:contain}.demo-visual svg{min-width:530px}.demo-output{max-width:100%}@media(max-width:760px){.demo-visual:after{content:'↔ Scroll diagram';display:block;color:var(--muted);font:11px var(--mono);padding:8px 0}html[lang=zh-CN] .demo-visual:after{content:'↔ 可左右滑动图解'}}