:root{
  --ink:#17222e; --muted:#4c6076; --line:#d3dce4; --bg:#fff;
  --accent:#0b5cad; --accent-ink:#fff; --done:#177245;
  --warn-bg:#fdf3e0; --warn-line:#c98a16; --soft:#f2f6fa;
  --mono:ui-monospace,"SF Mono",SFMono-Regular,Menlo,Consolas,monospace;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.45;font-size:16px}
::selection{background:#bfd9f2}
.wrap{max-width:780px;margin:0 auto;padding:0 18px}
.skip{position:absolute;left:-9999px;top:0;background:var(--ink);color:#fff;padding:8px 14px;z-index:50}
.skip:focus{left:8px;top:8px}
a{color:var(--accent);text-underline-offset:2px}
.mono{font-family:var(--mono);font-size:.82em}
.muted{color:var(--muted)}
:focus-visible{outline:3px solid var(--accent);outline-offset:2px}

/* header */
.top{background:#10263d;color:#eef4fa;border-bottom:1px solid #10263d}
.top a{color:#bcd6f2}
.top-row{padding-top:12px}
.course{margin:0;font-size:12.5px;color:#bcd6f2}
h1{margin:2px 0 10px;font-size:24px;letter-spacing:-.02em}
.stickybar{position:sticky;top:0;z-index:20;background:#10263d;color:#eef4fa;box-shadow:0 1px 4px rgba(16,38,61,.25)}
.sticky-row{display:flex;gap:12px;align-items:center;padding:7px 18px}
.progress-num{margin:0;font-weight:700;font-size:13.5px;white-space:nowrap}
.bar{height:8px;background:#2c4763;border-radius:4px;overflow:hidden;flex:1}
.bar>span{display:block;height:100%;width:0;background:#5cb85f;transition:width .35s ease-out}
.btn{appearance:none;border:1px solid var(--line);background:#fff;color:var(--ink);
  padding:10px 14px;border-radius:7px;font-size:14.5px;font-weight:600;cursor:pointer;min-height:44px}
.btn:hover{border-color:var(--muted)}
.btn.primary{background:var(--accent);border-color:var(--accent);color:var(--accent-ink)}
.btn.danger{color:#b3261e;border-color:#e0b3b0}
.btn.small{min-height:38px;padding:6px 14px}
.tools{display:flex;gap:14px;align-items:center;flex-wrap:wrap;padding:10px 18px 12px;border-top:1px solid #23405e;font-size:14px}
.search{flex:1 1 220px;display:flex;gap:8px;align-items:center}
.search input{flex:1;min-height:42px;border-radius:7px;border:1px solid #38597c;background:#0b1e33;color:#fff;padding:0 10px;font-size:15px}
.search input::placeholder{color:#9db8d2}
.toggle{display:flex;gap:7px;align-items:center;cursor:pointer;min-height:42px}
.toggle input{width:19px;height:19px;accent-color:#5cb85f}
.sync-mini{margin:0 0 0 auto;color:#bcd6f2;font-size:13px}

/* main */
main{padding-bottom:56px}
.upnext{border:2px solid var(--accent);border-radius:10px;padding:14px 16px;margin:18px 0 8px;background:var(--soft)}
.upnext-label{margin:0;font-size:12.5px;font-weight:800;letter-spacing:.07em;text-transform:uppercase;color:var(--accent)}
.upnext-text{margin:5px 0 2px;font-size:17.5px;font-weight:650}
.upnext-meta{margin:0;color:var(--muted)}
.upnext-actions{display:flex;gap:10px;margin-top:10px;flex-wrap:wrap}
.facts-box{margin:10px 0 6px;border-bottom:1px solid var(--line)}
.facts-box>summary{font-size:17px;font-weight:700;cursor:pointer;padding:10px 2px;min-height:44px}
.facts-box .facts{padding-bottom:8px}
h2{font-size:20px;letter-spacing:-.01em;margin:26px 0 8px}
.facts{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:6px 22px;margin:0}
.facts div{border-bottom:1px solid var(--line);padding:5px 0}
.facts dt{font-weight:700;font-size:13px;color:var(--muted)}
.facts dd{margin:1px 0 0;font-size:14.5px}
.callout{border:1px solid var(--warn-line);background:var(--warn-bg);border-radius:8px;padding:10px 13px;font-size:14.5px}
.modnav{display:flex;gap:8px;flex-wrap:wrap;margin:16px 0 4px}
.modnav a{border:1px solid var(--line);border-radius:999px;padding:7px 12px;text-decoration:none;font-size:13.5px;font-weight:600;color:var(--ink);background:#fff}
.modnav a .mono{color:var(--muted);font-weight:400}
.empty{color:var(--muted);padding:18px 0}

.module{margin-top:14px}
.mod-head{border-bottom:2px solid var(--ink);padding-bottom:6px}
.mod-head h2{margin-bottom:2px}
.mod-caption{margin:0;color:var(--muted);font-size:13.5px}
.mod-progress{margin:4px 0 0;font-weight:700;font-size:13.5px}
.mod-intro{margin:8px 0 0;font-size:14.5px;max-width:70ch}
.group{border-bottom:1px solid var(--line)}
.group>summary{display:flex;justify-content:space-between;align-items:center;gap:12px;
  padding:12px 2px;cursor:pointer;font-weight:700;font-size:16.5px;min-height:48px;list-style:none}
.group>summary::-webkit-details-marker{display:none}
.group>summary::after{content:"▸";color:var(--muted);font-weight:400}
.group[open]>summary::after{content:"▾"}
.group-progress{font-family:var(--mono);font-size:12.5px;color:var(--muted);font-weight:400;margin-left:auto}
.item{display:flex;gap:12px;align-items:flex-start;padding:11px 6px;min-height:48px;cursor:pointer;border-top:1px solid #e8edf2}
.item:hover{background:var(--soft)}
.item input{width:23px;height:23px;flex:none;margin-top:1px;accent-color:var(--done)}
.item-text{display:block;font-size:15.5px}
.item-meta{display:block;color:var(--muted)}
.item.is-done .item-text{color:var(--muted);text-decoration:line-through;text-decoration-thickness:1px}
.item.flash{animation:flash 1.6s ease-out}
@keyframes flash{0%{background:#dbeafe}100%{background:transparent}}
.block-note{font-size:14.5px;color:var(--muted);padding:8px 6px;margin:0}
.item-link{display:inline-block;margin:2px 0 8px 41px;font-size:14px}

.slides{padding:4px 0 14px 6px}
.slides>summary{cursor:pointer;font-weight:650;font-size:14.5px;color:var(--accent);min-height:40px;padding-top:8px}
.slide{border:1px solid var(--line);border-radius:9px;padding:13px 15px;margin:10px 0;background:#fff;box-shadow:0 1px 3px rgba(16,38,61,.08)}
.slide h4{margin:0 0 8px;font-size:15.5px}
.v3{font-family:var(--mono);font-size:11.5px;font-weight:400;color:var(--muted);border:1px solid var(--line);border-radius:4px;padding:1px 5px;white-space:nowrap}
.slide ul{margin:0;padding-left:20px}
.slide li,.slide p{font-size:14.5px;margin:4px 0;overflow-wrap:break-word}
.slide .sl-title{font-weight:700;font-size:15.5px}

.panel{border:1px solid var(--line);border-radius:10px;padding:6px 18px 18px;margin-top:30px;background:var(--soft)}
.panel p{font-size:14.5px;max-width:68ch}
.row{display:flex;gap:10px;align-items:flex-end;flex-wrap:wrap;margin:12px 0}
.row label{display:flex;flex-direction:column;gap:5px;font-size:13.5px;font-weight:600}
.row input[type=text],.row select{min-height:44px;border:1px solid var(--line);border-radius:7px;padding:0 10px;font-size:15px;background:#fff;color:var(--ink)}
.code{font-family:var(--mono);font-size:16px;background:#fff;border:1px solid var(--line);border-radius:6px;padding:5px 8px;overflow-wrap:anywhere}
.sync-status{font-weight:650}
.form-error{color:#b3261e;font-size:14px}
.file-btn{display:inline-flex;align-items:center}
.data-h{margin-top:8px}
.source{margin-top:26px;color:var(--muted);font-size:14px}
.source h2{color:var(--ink);font-size:16px}

@media (max-width:640px){
  h1{font-size:21px}
  .sync-mini{margin-left:0;width:100%}
  .item-text{font-size:15px}
}