:root{
  --paper:#f2f6fb; --card:#fff; --ink:#14284b; --muted:#5a6b88; --line:#d5deec;
  --sun:#f2b632; --classroom:#1e8e6e; --classroom-ink:#fff; --board:#14284b; --board-ink:#f6f9ff;
  --head:"Trebuchet MS","Segoe UI",Verdana,sans-serif;
  --body:"Segoe UI",Verdana,Arial,sans-serif;
}
@media (prefers-color-scheme:dark){
  :root{--paper:#0e1829;--card:#16243c;--ink:#eaf0fb;--muted:#9fb0cc;--line:#2a3b5a;--board:#0a1220;--classroom:#2fb48e;--classroom-ink:#06231a;}
}
*{box-sizing:border-box}
body{margin:0;background:var(--paper);color:var(--ink);font:400 1.08rem/1.65 var(--body)}
.wrap{max-width:760px;margin:0 auto;padding:0 20px}
a{color:inherit}
:focus-visible{outline:3px solid var(--sun);outline-offset:3px}
.links{display:flex;flex-wrap:wrap;gap:8px 20px;padding:22px 0 6px;font-weight:700;font-size:.97rem}
.board{background:var(--board);color:var(--board-ink);border-radius:18px;padding:30px 30px 26px;margin:14px 0 26px;border-bottom:8px solid var(--sun)}
.board h1{font:800 clamp(1.8rem,5vw,2.6rem)/1.12 var(--head);margin:0 0 6px}
.board .when{margin:0;color:#b9c8e3;font-size:.97rem}
section.block{background:var(--card);border:2px solid var(--line);border-radius:14px;padding:18px 22px;margin-bottom:16px}
section.block h2{font:800 1.25rem var(--head);margin:0 0 8px}
section.block p{margin:0 0 8px}
section.block ul,section.block ol{margin:0;padding-left:1.3em}
section.block li{margin-bottom:6px}
section.homework{border-color:var(--sun);border-width:3px}
.video{position:relative;padding-bottom:56.25%;height:0;border-radius:10px;overflow:hidden;margin-top:8px}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.submit{display:block;text-decoration:none;background:var(--classroom);color:var(--classroom-ink);border-radius:14px;padding:18px 22px;margin:22px 0}
.submit strong{display:block;font:800 1.25rem var(--head)}
.submit:hover{filter:brightness(1.07)}
ul.recentlist{list-style:none;padding:0;margin:0}
ul.recentlist li{border-bottom:1px solid var(--line);margin:0}
ul.recentlist a{display:block;padding:9px 2px;text-decoration:none}
ul.recentlist a:hover{text-decoration:underline}
footer{margin:44px 0 36px;padding-top:18px;border-top:1px solid var(--line);color:var(--muted);font-size:.93rem}