:root{
  --bg:#f4f6f9; --card:#fff; --ink:#1f2d3d; --muted:#68788d;
  --brand:#0e5e6f; --brand2:#12808f; --line:#e3e8ef;
  --clean:#0e8f76; --transport:#4459c7; --common:#c07f1f;
  --shadow:0 2px 10px rgba(16,42,67,.08);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);
  font-family:"Segoe UI","Microsoft JhengHei","PingFang TC",sans-serif;font-size:16px;line-height:1.65}
a{color:inherit;text-decoration:none}
img{max-width:100%}

/* ---------- header ---------- */
.topbar{position:sticky;top:0;z-index:50;display:flex;align-items:center;gap:14px;
  padding:10px 18px;background:linear-gradient(120deg,var(--brand),var(--brand2));color:#fff;
  box-shadow:0 2px 8px rgba(0,0,0,.18)}
.brand{display:flex;align-items:center;gap:10px;font-size:19px;font-weight:700;white-space:nowrap}
.brand img{height:30px;background:#fff;border-radius:6px;padding:2px 6px}
.searchbox{flex:1;max-width:520px}
.searchbox input{width:100%;padding:9px 14px;border:none;border-radius:22px;font-size:15px;outline:none;background:rgba(255,255,255,.94)}
.loginlink{font-size:14px;opacity:.9;border:1px solid rgba(255,255,255,.55);padding:6px 12px;border-radius:8px;white-space:nowrap}
.loginlink:hover{background:rgba(255,255,255,.15)}

main{max-width:1080px;margin:0 auto;padding:22px 16px 60px;min-height:70vh}

/* ---------- home ---------- */
.hero{background:linear-gradient(120deg,#0e5e6f,#1793a6 65%,#27ae8f);color:#fff;border-radius:18px;
  padding:34px 30px;margin-bottom:24px;box-shadow:var(--shadow)}
.hero h1{margin:0 0 8px;font-size:28px}
.hero p{margin:0;opacity:.92}
.hero .stats{display:flex;gap:10px;flex-wrap:wrap;margin-top:16px}
.hero .stat{background:rgba(255,255,255,.16);border:1px solid rgba(255,255,255,.3);
  border-radius:10px;padding:6px 14px;font-size:14px}
.catgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:16px}
.catcard{background:var(--card);border-radius:16px;padding:22px;box-shadow:var(--shadow);
  border-top:5px solid var(--brand);cursor:pointer;transition:transform .15s, box-shadow .15s}
.catcard:hover{transform:translateY(-3px);box-shadow:0 8px 22px rgba(16,42,67,.14)}
.catcard.clean{border-color:var(--clean)} .catcard.transport{border-color:var(--transport)} .catcard.common{border-color:var(--common)}
.catcard .ic{font-size:34px}
.catcard h2{margin:8px 0 6px;font-size:20px}
.catcard p{margin:0;color:var(--muted);font-size:14px}
.catcard .meta{margin-top:12px;font-size:13px;color:var(--muted);display:flex;justify-content:space-between}
.progressbar{height:6px;background:#e8edf3;border-radius:4px;margin-top:8px;overflow:hidden}
.progressbar i{display:block;height:100%;background:var(--brand2);border-radius:4px}

/* ---------- category page ---------- */
.pagehead{display:flex;align-items:center;gap:12px;margin:4px 0 18px}
.pagehead .ic{font-size:32px}
.pagehead h1{margin:0;font-size:24px}
.pagehead p{margin:2px 0 0;color:var(--muted);font-size:14px}
.subsec{margin:26px 0 10px;font-size:17px;font-weight:700;color:var(--brand);
  display:flex;align-items:center;gap:8px}
.subsec::after{content:"";flex:1;height:1px;background:var(--line)}
.lessongrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px}
.lesson{background:var(--card);border-radius:14px;padding:16px 18px;box-shadow:var(--shadow);
  cursor:pointer;display:flex;flex-direction:column;gap:8px;transition:transform .12s;position:relative}
.lesson:hover{transform:translateY(-2px)}
.lesson h3{margin:0;font-size:16.5px;line-height:1.45;padding-right:26px}
.lesson p{margin:0;color:var(--muted);font-size:13.5px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.lesson .badges{display:flex;gap:6px;flex-wrap:wrap}
.badge{font-size:12px;padding:2px 9px;border-radius:20px;background:#eef2f7;color:#51617a}
.badge.video{background:#fdeee0;color:#b3611a}
.badge.slides{background:#e5f2ff;color:#2465a8}
.badge.doc{background:#e7f6ef;color:#20835f}
.lesson .done{position:absolute;top:12px;right:14px;color:#27ae60;font-size:18px}

/* ---------- lesson page ---------- */
.crumb{font-size:13.5px;color:var(--muted);margin-bottom:12px}
.crumb a{color:var(--brand2)}
.lhead{background:var(--card);border-radius:16px;padding:22px 24px;box-shadow:var(--shadow);margin-bottom:20px}
.lhead h1{margin:0 0 8px;font-size:23px}
.lhead .desc{color:var(--muted);margin:0}
.lhead .badges{margin-top:12px;display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.markbtn{margin-left:auto;border:1px solid var(--line);background:#fff;color:var(--muted);
  padding:6px 14px;border-radius:8px;cursor:pointer;font-size:13.5px}
.markbtn.on{background:#eafaf0;border-color:#a8e6c1;color:#1e8449}
.slides-wrap{display:flex;flex-direction:column;gap:14px}
.slide{background:#fff;border-radius:12px;box-shadow:var(--shadow);overflow:hidden;cursor:zoom-in}
.slide img{display:block;width:100%}
.slide .no{font-size:12px;color:#9aa7b8;text-align:right;padding:4px 10px}
.vidgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:16px;margin-top:8px}
.vidcard{background:#fff;border-radius:12px;box-shadow:var(--shadow);overflow:hidden}
.vidcard video{width:100%;display:block;background:#000;aspect-ratio:16/9}
.vidcard .cap{padding:10px 14px;font-size:14.5px;font-weight:600}
.secttl{margin:28px 0 12px;font-size:18px;font-weight:700;color:var(--brand)}

/* ---------- custom lesson content ---------- */
.content{background:#fff;border-radius:16px;box-shadow:var(--shadow);padding:24px 26px;overflow-x:auto}
.content h3{color:var(--brand);margin:24px 0 10px;font-size:18px}
.content h3:first-child{margin-top:0}
.content h4{margin:0 0 8px;font-size:15.5px}
.banner{background:linear-gradient(120deg,var(--brand),var(--brand2));color:#fff;
  padding:12px 18px;border-radius:10px;font-size:16px;margin-bottom:18px}
.tbl{width:100%;border-collapse:collapse;font-size:14px;margin:6px 0 14px}
.tbl th{background:#eef3f8;color:#33475f;text-align:left;padding:8px 10px;border:1px solid var(--line)}
.tbl td{padding:8px 10px;border:1px solid var(--line);vertical-align:top}
.tbl.center td,.tbl.center th{text-align:center}
.tbl.small{font-size:13px}
.pts{margin:4px 0;padding-left:20px}
.pts li{margin:3px 0}
.card{background:#f9fbfd;border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin:8px 0}
.card.big{padding:18px 20px}
.grid2{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:14px}
.grid3{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:14px}
.steps .card{margin:10px 0}
.warn{background:#fff7e6;border:1px solid #f5d9a8;color:#8a5a12;border-radius:10px;padding:10px 14px;margin:14px 0;font-size:14.5px}
.warn.big{font-size:15.5px;padding:14px 18px}
.chip{display:inline-block;background:#e5f2ff;color:#2465a8;font-size:12.5px;padding:1px 9px;border-radius:16px;font-weight:600}
.chip.red{background:#fdecea;color:#c0392b}
.dot{display:inline-block;width:11px;height:11px;border-radius:50%;margin-right:6px;vertical-align:baseline;border:1px solid rgba(0,0,0,.15)}
.recipe{background:#eef7f4;border:1px dashed #9fd3c2;border-radius:10px;padding:10px 14px;margin-top:10px;font-size:15px}
.use{color:var(--muted);font-size:14px;margin:6px 0}

/* ---------- search ---------- */
.searchinfo{color:var(--muted);font-size:14px;margin-bottom:14px}
mark{background:#ffe9a8;padding:0 2px;border-radius:3px}

/* ---------- lightbox ---------- */
.lightbox{position:fixed;inset:0;z-index:100;background:rgba(10,18,28,.92);
  display:flex;align-items:center;justify-content:center}
.lightbox[hidden]{display:none}
.lightbox img{max-width:94vw;max-height:92vh;border-radius:6px}
.lightbox button{position:absolute;background:rgba(255,255,255,.12);color:#fff;border:none;
  font-size:26px;cursor:pointer;border-radius:50%;width:46px;height:46px;line-height:1}
.lightbox button:hover{background:rgba(255,255,255,.28)}
.lb-close{top:16px;right:18px}
.lb-prev{left:14px;top:50%;transform:translateY(-50%)}
.lb-next{right:14px;top:50%;transform:translateY(-50%)}
.lb-count{position:absolute;bottom:14px;left:50%;transform:translateX(-50%);color:#cfd8e3;font-size:14px}

.backtop{position:fixed;right:18px;bottom:22px;background:var(--brand2);color:#fff;border:none;
  width:44px;height:44px;border-radius:50%;font-size:20px;cursor:pointer;box-shadow:0 4px 12px rgba(0,0,0,.25);display:none}

.foot{text-align:center;color:#93a1b3;font-size:13px;padding:26px 10px 34px}

.empty{text-align:center;color:var(--muted);padding:60px 0;font-size:15px}

@media (max-width:640px){
  .topbar{flex-wrap:wrap}
  .brand{font-size:17px}
  .searchbox{order:3;max-width:none;flex-basis:100%}
  .loginlink{margin-left:auto}
  .hero{padding:24px 20px}
  .hero h1{font-size:22px}
  .content{padding:18px 14px}
  main{padding:14px 10px 50px}
}

/* 手機底部導覽列（App 化，桌機隱藏） */
.tr-appnav{display:none}
@media (max-width:768px){
  .tr-appnav{position:fixed;left:0;right:0;bottom:0;z-index:200;display:flex;
    background:#fff;border-top:1px solid #e2e8f0;box-shadow:0 -2px 10px rgba(15,23,42,.07);
    padding:5px 2px calc(8px + env(safe-area-inset-bottom))}
  .tr-appnav a{flex:1;display:flex;flex-direction:column;align-items:center;gap:2px;
    font-size:10px;font-weight:600;color:#64748b;text-decoration:none;padding:4px 1px}
  .tr-appnav a .ic{font-size:19px;line-height:1;filter:grayscale(35%);opacity:.82}
  .tr-appnav a.on{color:#122a4a;font-weight:700}
  .tr-appnav a.on .ic{filter:none;opacity:1}
  body{padding-bottom:calc(60px + env(safe-area-inset-bottom))}
}