:root{color-scheme:light dark;--bg:#f4f6fa;--card:#fff;--ink:#17233b;--muted:#58667c;--line:#dbe1ea;--accent:#2856b6}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.7 system-ui,sans-serif}header,main,footer{max-width:1080px;margin:auto;padding:24px}header{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap;align-items:center;border-bottom:1px solid var(--line)}nav{display:flex;gap:18px;flex-wrap:wrap}.brand{font-size:1.3rem;font-weight:750}.brand span{display:block;font-size:.8rem;color:var(--muted)}a{color:var(--accent);text-underline-offset:4px}h1{font-size:clamp(1.6rem,4vw,2.3rem);line-height:1.25}h2{font-size:1.25rem}small,article>span,.muted{color:var(--muted)}small{display:block;font-weight:400}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,280px),1fr));gap:16px;margin-top:20px}article{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:22px;margin:18px 0;overflow-wrap:anywhere}.grid article{margin:0}.math-copy{white-space:pre-wrap;overflow-wrap:anywhere}.katex-display{overflow-x:auto;overflow-y:hidden;padding:8px 0}img{display:block;max-width:100%;height:auto;margin:12px 0}.solution{border-left:3px solid var(--accent);padding:0 16px;margin-top:22px}li{padding:6px 0}.button{display:inline-block;border:1px solid var(--accent);border-radius:8px;padding:8px 14px}.notice{padding:16px;border:1px solid var(--line);border-radius:8px}footer{font-size:.9rem;border-top:1px solid var(--line)}@media(prefers-color-scheme:dark){:root{--bg:#101724;--card:#1a2435;--ink:#eef2f9;--muted:#b9c5d8;--line:#354358;--accent:#9cbbff}}@media(max-width:600px){header,main,footer{padding:16px}article{padding:16px}nav{gap:12px;font-size:.9rem}}
:root[data-theme="light"]{color-scheme:light;--bg:#f4f6fa;--card:#fff;--ink:#17233b;--muted:#58667c;--line:#dbe1ea;--accent:#2856b6}:root[data-theme="dark"]{color-scheme:dark;--bg:#101724;--card:#1a2435;--ink:#eef2f9;--muted:#b9c5d8;--line:#354358;--accent:#9cbbff}button,input,select,textarea{font:inherit;background:var(--card);color:var(--ink);border:1px solid var(--line);border-radius:8px;padding:8px 12px}button{cursor:pointer}.study-search{margin:22px 0}.study-search label{display:block;font-weight:600}.study-search>div{display:flex;gap:10px;flex-wrap:wrap}.study-search input{flex:1;min-width:140px}