:root{--paper:#f8fafc;--ink:#18304a;--muted:#4c6073;--accent:#2458a6;--line:#cbd5e1;--wash:#edf3fa;--space:24px;color-scheme:light;font-family:"Microsoft YaHei","PingFang SC",system-ui,sans-serif;color:var(--ink);background:var(--paper);font-size:16px;line-height:1.75}
*{box-sizing:border-box}body{margin:0}a{color:var(--accent);text-underline-offset:5px}button,input{font:inherit}a,button,input,summary{-webkit-tap-highlight-color:transparent}button,summary,input[type=radio]{cursor:pointer}:focus-visible{outline:3px solid var(--accent);outline-offset:5px}.wrap{width:min(1120px,calc(100% - 64px));margin-inline:auto}.skip{position:absolute;left:16px;top:-100px;padding:8px 16px;background:var(--paper);z-index:2}.skip:focus{top:12px}.header{display:flex;justify-content:space-between;align-items:center;gap:24px;padding-block:26px;border-bottom:1px solid var(--line)}.brand{display:flex;gap:12px;align-items:center;color:var(--ink);font-size:18px;font-weight:700;text-decoration:none}.brand-mark{display:grid;place-items:center;width:42px;height:42px;background:var(--ink);color:var(--paper);border-radius:10px;font-size:17px}nav{display:flex;gap:24px}nav a{display:flex;align-items:center;min-height:44px;color:var(--muted);font-size:14px;text-decoration:none}nav a:hover{text-decoration:underline;color:var(--accent)}.intro{display:grid;grid-template-columns:1.1fr 1fr;gap:64px;align-items:center;padding-block:76px 80px}.lead-label{font-size:16px;color:var(--accent);margin:0 0 20px}h1{font-size:clamp(32px,3.6vw,48px);line-height:1.35;letter-spacing:-1px;margin:0 0 24px}h2{font-size:28px;line-height:1.4;margin:0}h3{font-size:22px;line-height:1.5;margin:0 0 12px}h4{font-size:24px;line-height:1.5;margin:14px 0 18px}p{margin:0 0 16px}.intro-text{color:var(--muted);max-width:31em;margin-bottom:28px}.primary-link{display:inline-flex;align-items:center;min-height:48px;padding:9px 22px;background:var(--accent);color:var(--paper);text-decoration:none;border-radius:7px;font-weight:600}.primary-link:hover{background:#1d4888}.quiet{font-size:13px;color:var(--muted);margin:14px 0 0}.specimen{background:var(--wash);padding:28px 32px 24px;border-radius:18px 18px 54px 18px;border:1px solid #d4dfed}.specimen-top{display:flex;justify-content:space-between;color:var(--muted);font-size:13px;gap:16px}.specimen-title{font-size:34px;font-weight:700;line-height:1.5;margin:30px 0 22px}.specimen-body{font-size:16px;max-width:24em}.specimen-bottom{display:flex;gap:24px;padding-top:24px;margin-top:24px;border-top:1px solid #c4d1e2;font-size:13px;color:var(--muted)}.section{padding-block:56px 64px;border-top:1px solid var(--line);scroll-margin-top:24px}.section-heading{margin-bottom:40px}.section-heading p{color:var(--muted);margin:12px 0 0}.exercise{display:grid;grid-template-columns:320px 1fr;gap:64px;align-items:start}.exercise-description>p{color:var(--muted)}.exercise-description>label{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:18px;font-size:14px}.exercise-description output{font-variant-numeric:tabular-nums;color:var(--accent)}input[type=range]{display:block;width:100%;height:44px;margin:0;accent-color:var(--accent)}.text-button{min-height:44px;border:0;padding:0 2px;background:transparent;color:var(--accent);text-decoration:underline;text-underline-offset:5px;margin-top:6px}.preview{padding:32px;border:1px solid var(--line);border-radius:12px;min-width:0}.preview-label{font-size:13px;color:var(--muted)}#sample-text{font-size:18px;line-height:1.8;margin:0;overflow-wrap:anywhere}.color-exercise{margin-top:64px}.color-preview{background:var(--wash);color:var(--ink);border-color:transparent}.color-preview .preview-label{color:inherit;opacity:.85}.color-preview p{margin-bottom:24px}.color-codes{font-size:13px;display:block;overflow-wrap:anywhere}.contrast{font-size:14px;margin-top:20px!important}.contrast output{margin-left:10px;font-weight:700}fieldset{border:0;padding:0;margin:24px 0 0;display:flex;gap:14px;flex-wrap:wrap}legend{font-size:14px;margin-bottom:8px}.choice{display:flex;align-items:center;gap:7px;min-height:44px;cursor:pointer}input[type=radio]{accent-color:var(--accent);width:17px;height:17px}details{border-bottom:1px solid var(--line);padding-block:6px}summary{padding:16px 4px;font-weight:600;min-height:52px}details p{max-width:70ch;color:var(--muted);margin:0;padding:0 4px 20px}.about{display:grid;grid-template-columns:320px 1fr;gap:64px}.about p{color:var(--muted)}.about p:last-child{margin-bottom:0}.footer{border-top:1px solid var(--line);padding-block:28px;display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px 24px;font-size:13px;color:var(--muted)}.footer a{min-height:32px}.notice{padding:16px;background:var(--wash);margin-top:24px}
@media(max-width:900px){.intro{gap:32px}.exercise,.about{grid-template-columns:260px 1fr;gap:32px}.specimen{padding:24px}.specimen-title{font-size:28px}}
@media(max-width:680px){.wrap{width:calc(100% - 40px)}.header{align-items:flex-start;flex-direction:column;gap:10px;padding-block:20px 12px}nav{gap:24px}.brand{font-size:17px}.intro{grid-template-columns:1fr;gap:32px;padding-block:40px 48px}h1{font-size:34px}h2{font-size:25px}.specimen{border-radius:12px 12px 32px 12px}.specimen-title{margin-top:24px}.section{padding-block:36px 40px}.section-heading{margin-bottom:28px}.exercise,.about{grid-template-columns:1fr;gap:24px}.preview{padding:24px}.color-exercise{margin-top:40px}.footer{flex-direction:column;gap:8px;padding-block:24px}.about{gap:18px}}