/* =========================================================
   MẪU MÀU — đổi mẫu mặc định ở js/data.js (SITE.giaoDien)
   ========================================================= */
:root,[data-theme="trang"]{
  /* Trắng tối giản – điểm nhấn xanh dương */
  --navy:#1e293b; --navy-2:#0f172a; --ink:#1f2937; --text-2:#475569; --muted:#64748b;
  --bg:#ffffff; --card:#fff; --soft:#f1f5f9; --line:#e5e7eb;
  --accent:#2563eb; --accent-h:#1d4ed8; --on-accent:#fff; --hl:#2563eb; --mark:#2563eb;
  --top-bg:#f8fafc; --top-fg:#475569;
  --nav-bg:#fff; --nav-fg:#1e293b; --nav-hover:#f1f5f9; --nav-active:#2563eb;
  --hero-bg:linear-gradient(180deg,#f8fafc,#fff); --hero-fg:#0f172a; --hero-sub:#475569;
  --sel-bg:#2563eb; --sel-fg:#fff;
  --band-bg:#f1f5f9; --band-fg:#0f172a; --band-btn:#fff; --band-btn-fg:#1e293b;
  --foot-bg:#f8fafc; --foot-bg2:#f1f5f9; --foot-fg:#475569; --foot-h:#0f172a; --foot-card:#fff;
  --shadow:0 2px 10px rgba(15,23,42,.06); --shadow-h:0 12px 30px rgba(15,23,42,.12);
  --radius:14px;
}
[data-theme="xanh-la"]{
  /* Trắng – xanh ngọc */
  --navy:#134e4a; --navy-2:#042f2e; --text-2:#3f5f5c; --muted:#5f7a77; --soft:#ecfdf5; --line:#d9efe8;
  --accent:#0f9488; --accent-h:#0f766e; --hl:#0f9488; --mark:#0f9488;
  --top-bg:#0f766e; --top-fg:#ccfbf1;
  --nav-fg:#134e4a; --nav-hover:#ecfdf5; --nav-active:#0f9488;
  --hero-bg:linear-gradient(135deg,#ecfdf5,#f0fdfa 60%,#fff); --hero-fg:#042f2e; --hero-sub:#3f5f5c;
  --sel-bg:#0f9488; --band-bg:#0f766e; --band-fg:#fff; --band-btn:#fff; --band-btn-fg:#0f766e;
  --foot-bg:#f0fdfa; --foot-bg2:#ccfbf1; --foot-fg:#3f5f5c; --foot-h:#042f2e;
}
[data-theme="navy"]{
  /* Xanh navy (mẫu ban đầu) */
  --navy:#13315c; --navy-2:#0b2545; --text-2:#475467; --muted:#667085; --bg:#f6f7fb; --soft:#eef2f8; --line:#e6e9ef;
  --accent:#13315c; --accent-h:#1d4a8a; --hl:#2563c9; --mark:#f4b400;
  --top-bg:#0b2545; --top-fg:#cfd8e6;
  --nav-bg:#13315c; --nav-fg:#fff; --nav-hover:rgba(255,255,255,.1); --nav-active:#f4b400;
  --hero-bg:linear-gradient(135deg,#0b2545,#13315c); --hero-fg:#fff; --hero-sub:#cdd8ea;
  --sel-bg:#13315c; --band-bg:#f4b400; --band-fg:#0b2545; --band-btn:#0b2545; --band-btn-fg:#fff;
  --foot-bg:#0b2545; --foot-bg2:#081c35; --foot-fg:#b8c6dc; --foot-h:#fff; --foot-card:rgba(255,255,255,.06);
}
[data-theme="navy"] .hero h1 span,[data-theme="navy"] .hero-stats b{color:#ffd54a}
[data-theme="navy"] .hero .btn-gold{background:#f4b400;color:#0b2545}
[data-theme="cam"]{
  /* Trắng ấm – cam san hô */
  --navy:#43302b; --navy-2:#2a1d19; --text-2:#5d4b45; --muted:#86736c; --bg:#fffdfb; --soft:#fff1ea; --line:#f3e3da;
  --accent:#ea580c; --accent-h:#c2410c; --hl:#ea580c; --mark:#ea580c;
  --top-bg:#fff7f2; --top-fg:#7c4a35;
  --nav-fg:#43302b; --nav-hover:#fff1ea; --nav-active:#ea580c;
  --hero-bg:linear-gradient(135deg,#fff4ec,#fffdfb); --hero-fg:#2a1d19; --hero-sub:#5d4b45;
  --sel-bg:#ea580c; --band-bg:#fff1ea; --band-fg:#2a1d19; --band-btn:#ea580c; --band-btn-fg:#fff;
  --foot-bg:#fff7f2; --foot-bg2:#fff1ea; --foot-fg:#5d4b45; --foot-h:#2a1d19;
}
[data-theme="tim"]{
  /* Trắng – tím nhẹ */
  --navy:#312e81; --navy-2:#1e1b4b; --text-2:#4b4a6b; --muted:#6b6a8a; --soft:#f3f1ff; --line:#e6e3f7;
  --accent:#6d28d9; --accent-h:#5b21b6; --hl:#6d28d9; --mark:#7c3aed;
  --top-bg:#f5f3ff; --top-fg:#4c1d95;
  --nav-fg:#312e81; --nav-hover:#f3f1ff; --nav-active:#7c3aed;
  --hero-bg:linear-gradient(135deg,#f5f3ff,#fff); --hero-fg:#1e1b4b; --hero-sub:#4b4a6b;
  --sel-bg:#6d28d9; --band-bg:#f3f1ff; --band-fg:#1e1b4b; --band-btn:#6d28d9; --band-btn-fg:#fff;
  --foot-bg:#faf9ff; --foot-bg2:#f3f1ff; --foot-fg:#4b4a6b; --foot-h:#1e1b4b;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"Segoe UI",-apple-system,BlinkMacSystemFont,Roboto,Helvetica,Arial,sans-serif;-webkit-font-smoothing:antialiased;color:var(--ink);background:var(--bg);line-height:1.55;font-size:15px}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
button{font:inherit;cursor:pointer}
.container{max-width:1800px;margin:0 auto;padding:0 clamp(16px,3vw,48px)}

/* ---------- Topbar ---------- */
.topbar{background:var(--top-bg);color:var(--top-fg);font-size:13px;border-bottom:1px solid var(--line)}
.topbar-in{display:flex;justify-content:space-between;align-items:center;height:34px}
.topbar-social a{margin-left:14px;opacity:.85}
.topbar-social a:hover{opacity:1;text-decoration:underline}

/* ---------- Header ---------- */
.header{background:#fff;position:sticky;top:0;z-index:50;box-shadow:0 2px 12px rgba(0,0,0,.05)}
.header-in{display:flex;align-items:center;gap:24px;height:88px}
.logo{display:flex;align-items:center;gap:10px;flex-shrink:0}
.logo-mark{width:66px;height:66px;border-radius:12px;object-fit:cover;box-shadow:0 2px 8px rgba(15,23,42,.12);flex-shrink:0}
.logo-text{display:flex;flex-direction:column;line-height:1.1}
.logo-text b{font-size:34px;font-weight:800;color:var(--navy);letter-spacing:.2px;line-height:1.1}
.logo-text small{font-size:17px;font-weight:600;color:var(--accent);margin-top:3px;letter-spacing:.3px}
.logo-light .logo-text b{color:var(--foot-h)}.logo-light .logo-text small{color:var(--muted)}

.search{flex:1;display:flex;max-width:620px;margin-left:auto;border:2px solid var(--accent);border-radius:999px;overflow:hidden;background:#fff}
.search select{border:0;background:var(--soft);padding:0 12px;font:inherit;font-size:14px;color:var(--navy);max-width:170px;outline:none;cursor:pointer}
.search input{flex:1;border:0;padding:10px 14px;font:inherit;outline:none;min-width:0}
.search button{border:0;background:var(--accent);color:var(--on-accent);width:52px}
.search button:hover{background:var(--accent-h)}

.burger{display:none;background:none;border:0;width:40px;height:40px;padding:8px;margin-left:auto}
.burger span{display:block;height:2px;background:var(--navy);margin:5px 0;border-radius:2px;transition:.25s}

/* ---------- Menu ---------- */
.nav{background:var(--nav-bg);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.menu{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap}
.menu>li{position:relative}
.menu>li>a{display:flex;align-items:center;gap:6px;padding:14px 18px;color:var(--nav-fg);font-weight:700;font-size:14px;text-transform:uppercase;letter-spacing:.3px;transition:background .2s}
.menu>li>a:hover,.menu>li.active>a{background:var(--nav-hover)}
.menu>li.active>a{box-shadow:inset 0 -3px 0 var(--nav-active)}
.caret{width:0;height:0;border:4px solid transparent;border-top-color:currentColor;margin-top:4px}
.sub{position:absolute;left:0;top:100%;background:#fff;min-width:320px;padding:12px;border-radius:0 0 12px 12px;box-shadow:var(--shadow-h);display:grid;grid-template-columns:repeat(3,1fr);gap:4px;opacity:0;visibility:hidden;transform:translateY(8px);transition:.2s;list-style:none;margin:0;z-index:60}
.menu>li:hover .sub,.menu>li:focus-within .sub{opacity:1;visibility:visible;transform:none}
.sub a{display:block;padding:8px 10px;border-radius:8px;font-size:14px;font-weight:500;color:var(--ink);white-space:nowrap}
.sub a:hover{background:var(--soft);color:var(--navy)}
.sub .sub-all{grid-column:1/-1;font-weight:700;color:var(--navy);border-bottom:1px solid var(--line);border-radius:8px 8px 0 0;margin-bottom:4px}
.sub .cnt{font-size:11px;color:var(--muted);margin-left:4px}
.sub-toggle{display:none}

/* ---------- Hero ---------- */
.hero{background:var(--hero-bg);background:linear-gradient(90deg,rgba(255,255,255,.82),rgba(255,255,255,.45));color:var(--hero-fg);border-bottom:1px solid var(--line);padding:56px 0 64px;position:relative;overflow:hidden}
.hero::after{content:"∑  π  √x  ∫  Δ  ∞  sin  ≤  θ  f(x)";position:absolute;right:-20px;bottom:-12px;font-size:64px;font-family:Georgia,serif;opacity:.06;white-space:nowrap;letter-spacing:12px}
.hero h1{font-size:30px;line-height:1.25;margin:0 0 10px;font-weight:700}
.hero h1 span{color:var(--hl)}
.hero p{font-size:15px;color:var(--hero-sub);margin:0 0 24px}
.hero-btns{display:flex;gap:12px;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 22px;border-radius:999px;font-weight:700;border:0;transition:.2s}
.btn-gold{background:var(--accent);color:var(--on-accent)}.btn-gold:hover{background:var(--accent-h);transform:translateY(-2px)}
.btn-ghost{background:#fff;color:var(--navy-2);border:1px solid var(--line)}.btn-ghost:hover{background:var(--soft)}
.btn-navy{background:var(--accent);color:var(--on-accent)}.btn-navy:hover{background:var(--accent-h)}
.btn-line{background:#fff;color:var(--accent);border:2px solid var(--accent)}.btn-line:hover{background:var(--soft)}
.hero-stats{display:flex;gap:10px;margin-top:24px;flex-wrap:wrap}
.hero-stats>div{background:#fff;border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:10px;padding:6px 14px 6px 12px;min-width:0;box-shadow:var(--shadow);display:flex;align-items:baseline;gap:6px}
.hero-stats b{display:block;font-size:18px;color:var(--hl)}
.hero-stats span{font-size:13px;color:var(--text-2);font-weight:500}

/* ---------- Category tiles ---------- */
.tiles{display:grid;grid-template-columns:repeat(5,1fr);gap:16px;margin-top:-34px;position:relative;z-index:2}
.tile{background:#fff;border-radius:var(--radius);padding:20px;box-shadow:var(--shadow);border-top:4px solid var(--c);transition:.25s}
.tile:hover{transform:translateY(-4px);box-shadow:var(--shadow-h)}
.tile-ico{width:58px;height:58px;border-radius:16px;background:color-mix(in srgb,var(--c) 10%,#fff);color:var(--c);display:grid;place-items:center;font-size:22px;margin-bottom:10px}
.tile h3{margin:0 0 4px;font-size:16px;color:var(--navy)}
.tile p{margin:0;font-size:13px;color:var(--muted)}
.tile small{display:inline-block;margin-top:8px;font-weight:700;font-size:12px;color:var(--c)}

/* ---------- Sections ---------- */
.section{padding:44px 0 8px}
.sec-head{display:flex;align-items:end;justify-content:space-between;gap:16px;margin-bottom:18px}
.sec-head h2{margin:0;font-size:24px;color:var(--navy);font-weight:700;position:relative;padding-left:14px}
.sec-head h2::before{content:"";position:absolute;left:0;top:4px;bottom:4px;width:5px;border-radius:4px;background:var(--mark)}
.sec-head a{font-weight:700;color:var(--navy);font-size:14px;white-space:nowrap}
.sec-head a:hover{color:var(--hl)}
.grade-chips{display:flex;flex-wrap:wrap;gap:8px;margin:-4px 0 18px}
.chip{padding:6px 14px;border-radius:999px;background:#fff;border:1px solid var(--line);font-size:13px;font-weight:600;color:var(--ink);transition:.15s}
.chip:hover{border-color:var(--accent);color:var(--navy)}
.chip.on{background:var(--sel-bg);border-color:var(--sel-bg);color:var(--sel-fg)}
.chip.dim{opacity:.45}

/* ---------- Cards ---------- */
.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:22px}
.grid.g3{grid-template-columns:repeat(3,1fr)}
.grid>*,.tiles>*,.archive>*,.detail>*{min-width:0}
.app{overflow-x:clip}
.card{background:var(--card);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow);transition:.25s;display:flex;flex-direction:column}
.card:hover{transform:translateY(-5px);box-shadow:var(--shadow-h)}
.thumb{position:relative;aspect-ratio:4/3;overflow:hidden;background:var(--soft)}
.thumb img{width:100%;height:100%;object-fit:cover;object-position:top;transition:transform .5s}
.card:hover .thumb img{transform:scale(1.06)}
.thumb .badge{position:absolute;top:10px;left:10px;background:var(--c);color:#fff;font-size:11px;font-weight:700;padding:4px 9px;border-radius:6px;letter-spacing:.3px}
.thumb .new{position:absolute;top:10px;right:10px;background:#facc15;color:#422006;font-size:11px;font-weight:700;padding:4px 8px;border-radius:6px}
.quick{position:absolute;left:50%;bottom:14px;transform:translate(-50%,16px);opacity:0;background:#fff;color:var(--navy);border:0;padding:8px 16px;border-radius:999px;font-weight:700;font-size:13px;box-shadow:0 6px 16px rgba(0,0,0,.18);transition:.25s;white-space:nowrap}
.card:hover .quick,.quick:focus{opacity:1;transform:translate(-50%,0)}
.quick:hover{background:var(--accent);color:var(--on-accent)}
.ph{width:100%;height:100%;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center;padding:18px;color:#fff;background:linear-gradient(135deg,var(--c),color-mix(in srgb,var(--c) 55%,#0f172a))}
.ph .ph-ico{width:64px;height:64px;margin-bottom:10px;color:#fff;background:rgba(255,255,255,.14);border-radius:18px;display:grid;place-items:center}.ph .ph-ico svg{width:42px;height:42px}.ph .ph-ico svg [fill="#fff"]{fill:color-mix(in srgb,var(--c) 70%,#0f172a)}
.ph .ph-t{font-weight:700;font-size:16px;line-height:1.3}
.ph .ph-s{font-size:12px;opacity:.85;margin-top:6px}
.card-body{padding:14px 16px 16px;display:flex;flex-direction:column;gap:6px;flex:1}
.card-cat{font-size:12px;color:var(--muted);font-weight:500}
.card-cat a:hover{color:var(--navy)}
.card-title{margin:0;font-size:14.5px;font-weight:700;text-transform:uppercase;line-height:1.35;color:var(--navy)}
.card-title a:hover{color:var(--hl)}
.card-meta{margin-top:auto;padding-top:8px;display:flex;justify-content:space-between;align-items:center;font-size:12px;color:var(--muted);border-top:1px dashed var(--line)}
.card-meta .dl{color:var(--accent);font-weight:700}

/* ---------- Archive ---------- */
.page-head{background:#fff;border-bottom:1px solid var(--line);padding:22px 0}
.crumb{font-size:13px;color:var(--muted);margin-bottom:6px}
.crumb a:hover{color:var(--navy)}
.crumb span{margin:0 6px}
.page-head h1{margin:0;font-size:28px;color:var(--navy);font-weight:700}
.page-head p{margin:4px 0 0;color:var(--muted)}
.archive{display:grid;grid-template-columns:260px 1fr;gap:28px;padding-top:28px;padding-bottom:48px}
.side .widget{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:18px;margin-bottom:20px}
.widget h3{margin:0 0 12px;font-size:15px;text-transform:uppercase;color:var(--navy);letter-spacing:.4px;padding-bottom:10px;border-bottom:2px solid var(--mark)}
.wlist{list-style:none;margin:0;padding:0}
.wlist a{display:flex;justify-content:space-between;padding:7px 8px;border-radius:8px;font-size:14px}
.wlist a:hover{background:var(--soft);color:var(--navy)}
.wlist a.on{background:var(--sel-bg);color:var(--sel-fg);font-weight:700}
.wlist a.on em{color:inherit;opacity:.85}
.wlist em{font-style:normal;font-size:12px;color:var(--muted)}
.wlist a.zero{opacity:.5}
.toolbar{display:flex;justify-content:space-between;align-items:center;gap:12px;background:#fff;padding:10px 14px;border-radius:12px;box-shadow:var(--shadow);margin-bottom:20px;flex-wrap:wrap}
.toolbar .res{font-size:14px;color:var(--muted)}
.toolbar select{font:inherit;font-size:14px;padding:7px 10px;border-radius:8px;border:1px solid var(--line);background:#fff;color:var(--ink)}
.filter-btn{display:none;border:1px solid var(--line);background:#fff;padding:7px 12px;border-radius:8px;font-weight:600}
.empty{background:#fff;border-radius:var(--radius);padding:48px 24px;text-align:center;color:var(--muted);box-shadow:var(--shadow)}
.empty .big{font-size:46px;margin-bottom:6px}
.empty h3{margin:0 0 6px;color:var(--navy)}

.pager{display:flex;justify-content:center;gap:6px;margin-top:30px;flex-wrap:wrap}
.pager a,.pager span{min-width:40px;height:40px;display:grid;place-items:center;border-radius:10px;background:#fff;border:1px solid var(--line);font-weight:700;color:var(--navy);padding:0 10px}
.pager a:hover{border-color:var(--accent)}
.pager .cur{background:var(--sel-bg);color:var(--sel-fg);border-color:var(--sel-bg)}
.pager .dots{border:0;background:none}

/* ---------- Detail ---------- */
.detail{display:grid;grid-template-columns:1.25fr 1fr;gap:32px;padding-top:28px;padding-bottom:20px;align-items:start}
.viewer{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:14px}
.viewer .main-img{border-radius:10px;overflow:hidden;background:var(--soft);cursor:zoom-in}
.viewer .main-img .ph{aspect-ratio:4/3}
.thumbs{display:flex;gap:10px;margin-top:10px}
.thumbs img{width:76px;height:76px;object-fit:cover;object-position:top;border-radius:8px;border:2px solid transparent;cursor:pointer}
.thumbs img.on{border-color:var(--accent)}
.info{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:24px}
.info .card-cat{font-size:13px}
.info h1{margin:6px 0 12px;font-size:26px;line-height:1.3;color:var(--navy);font-weight:700}
.info p{color:var(--text-2)}
.tags{display:flex;flex-wrap:wrap;gap:6px;margin:12px 0 18px}
.tag{background:var(--soft);color:var(--navy);font-size:12px;font-weight:600;padding:4px 10px;border-radius:999px}
.dl-list{display:flex;flex-direction:column;gap:10px;margin:18px 0}
.dl-list .btn{justify-content:center}
.meta-table{width:100%;border-collapse:collapse;font-size:14px;margin-top:8px}
.meta-table td{padding:8px 0;border-top:1px solid var(--line)}
.meta-table td:first-child{color:var(--muted);width:42%}
.share{display:flex;gap:8px;margin-top:16px;flex-wrap:wrap}
.share button,.share a{font-size:13px;padding:7px 12px;border-radius:8px;border:1px solid var(--line);background:#fff;font-weight:600}
.share button:hover,.share a:hover{border-color:var(--accent);color:var(--navy)}

/* ---------- Community / static pages ---------- */
.comm-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.comm{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:26px;transition:.25s;border-top:4px solid var(--c)}
.comm:hover{transform:translateY(-4px);box-shadow:var(--shadow-h)}
.comm .tile-ico{width:64px;height:64px}.comm .tile-ico svg{width:40px;height:40px}
.comm h3{margin:6px 0;color:var(--navy)}
.comm p{color:var(--muted);margin:0 0 14px;font-size:14px}
.comm .btn{padding:9px 18px;font-size:14px}
.prose{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:28px;max-width:860px}
.prose h2{color:var(--navy);margin-top:0}
.form{display:grid;gap:12px}
.form input,.form textarea,.form select{font:inherit;padding:11px 14px;border:1px solid var(--line);border-radius:10px;background:var(--soft);width:100%}
.form textarea{min-height:110px;resize:vertical}
.form .row{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.note{font-size:13px;color:var(--muted)}

/* ---------- Footer ---------- */
.footer{background:var(--foot-bg);color:var(--foot-fg);margin-top:56px;border-top:1px solid var(--line)}
.footer-follow{background:var(--band-bg);color:var(--band-fg);border-bottom:1px solid var(--line);padding:22px 0;text-align:center}
.footer-follow h3{margin:0 0 12px;font-size:18px;font-weight:700;letter-spacing:.5px}
.follow-icons{display:flex;justify-content:center;gap:12px;flex-wrap:wrap}
.follow-icons a{background:var(--band-btn);color:var(--band-btn-fg);border:1px solid var(--line);padding:9px 18px;border-radius:999px;font-weight:700;font-size:14px;transition:.2s}
.follow-icons a:hover{background:var(--accent);color:var(--on-accent);border-color:var(--accent)}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1.4fr;gap:32px;padding-top:40px;padding-bottom:40px}
.footer h4{color:var(--foot-h);margin:0 0 14px;font-size:15px;text-transform:uppercase;letter-spacing:.5px}
.ft-desc{font-size:14px;margin-top:14px}
.ft-links{list-style:none;margin:0;padding:0}
.ft-links li{margin-bottom:8px;font-size:14px}
.ft-links a:hover{color:var(--hl)}
.author{display:flex;gap:14px;align-items:flex-start;background:var(--foot-card);padding:14px;border-radius:12px;border:1px solid var(--line)}
.avatar{width:56px;height:56px;border-radius:50%;background:var(--accent);color:var(--on-accent);font-weight:700;font-size:24px;display:grid;place-items:center;flex-shrink:0}
.author b{color:var(--foot-h)}
.author p{margin:4px 0 0;font-size:13px}
.copyright{border-top:1px solid var(--line);background:var(--foot-bg2);padding:16px 0;font-size:13px;text-align:center}
.to-top{position:fixed;right:18px;bottom:18px;width:44px;height:44px;border-radius:50%;border:0;background:var(--accent);color:var(--on-accent);font-size:20px;box-shadow:var(--shadow-h);opacity:0;visibility:hidden;transition:.25s;z-index:40}
.to-top.show{opacity:1;visibility:visible}
.to-top:hover{background:var(--accent-h)}

/* ---------- Modal ---------- */
.modal{position:fixed;inset:0;background:rgba(15,23,42,.6);display:none;align-items:center;justify-content:center;padding:16px;z-index:100}
.modal.open{display:flex}
.modal-box{background:#fff;border-radius:16px;max-width:980px;width:100%;max-height:92vh;overflow:auto;position:relative}
.modal-close{position:absolute;right:10px;top:10px;width:38px;height:38px;border-radius:50%;border:0;background:var(--soft);font-size:24px;line-height:1;z-index:2}
.modal-close:hover{background:var(--accent);color:var(--on-accent)}
.qv{display:grid;grid-template-columns:1.1fr 1fr;gap:24px;padding:24px}
.qv .qimg{border-radius:10px;overflow:hidden;background:var(--soft);max-height:72vh;overflow-y:auto}
.qv .qimg .ph{aspect-ratio:4/3}
.qv h2{margin:6px 0 10px;color:var(--navy);font-size:22px}
.qv p{color:var(--text-2)}
.zoom-img{padding:8px}
.zoom-img img{margin:0 auto}

/* ---------- Responsive ---------- */
@media (max-width:1100px){
  .grid{grid-template-columns:repeat(3,1fr)}
  .tiles{grid-template-columns:repeat(3,1fr)}
}
@media (max-width:900px){
  .header-in{flex-wrap:wrap;height:auto;padding-top:10px;padding-bottom:10px;gap:10px}
  .burger{display:block}
  .search{order:3;flex-basis:100%;max-width:none}
  .nav{display:none}
  .nav.open{display:block}
  .menu{flex-direction:column;padding:6px 0}
  .menu>li>a{padding:12px 4px}
  .menu>li{display:flex;flex-wrap:wrap;align-items:center}
  .menu>li>a{flex:1}
  .menu .caret{display:none}
  .sub-toggle{display:block;background:none;border:0;color:var(--nav-fg);font-size:20px;width:44px;height:44px}
  .sub{position:static;opacity:1;visibility:visible;transform:none;display:none;flex-basis:100%;min-width:0;border-radius:10px;margin-bottom:8px;grid-template-columns:repeat(4,1fr)}
  .menu>li.sub-open .sub{display:grid}
  .menu>li:hover .sub{display:none}.menu>li.sub-open:hover .sub{display:grid}
  .archive{grid-template-columns:1fr}
  .side{display:none}
  .side.open{display:block}
  .filter-btn{display:inline-flex}
  .detail{grid-template-columns:1fr}
  .info{position:static}
  .qv{grid-template-columns:1fr}
  .comm-grid{grid-template-columns:repeat(2,1fr)}
  .footer-grid{grid-template-columns:1fr 1fr}
  .hero h1{font-size:24px}
}
@media (max-width:600px){
  .topbar-social{display:none}
  .grid,.grid.g3{grid-template-columns:repeat(2,1fr);gap:12px}
  .tiles{grid-template-columns:repeat(2,1fr)}
  .card-body{padding:10px 12px 12px}
  .card-title{font-size:13px}
  .quick{display:none}
  .comm-grid,.footer-grid,.form .row{grid-template-columns:1fr}
  .sub{grid-template-columns:repeat(3,1fr)}
  .search select{max-width:110px}
  .hero{padding:36px 0 56px}
  .hero h1{font-size:21px}
  .sec-head h2{font-size:20px}
}

/* ---------- Bảng chọn mẫu màu ---------- */
.theme-pick{position:fixed;left:18px;bottom:18px;z-index:45;font-size:14px}
.theme-pick>button{border:1px solid #e5e7eb;background:#fff;color:#1f2937;padding:10px 16px;border-radius:999px;font-weight:700;box-shadow:0 12px 30px rgba(15,23,42,.15)}
.theme-pick .tp-list{position:absolute;left:0;bottom:52px;background:#fff;border:1px solid #e5e7eb;border-radius:14px;box-shadow:0 12px 30px rgba(15,23,42,.15);padding:8px;width:260px;display:none}
.theme-pick.open .tp-list{display:block}
.tp-list b{display:block;padding:6px 8px 8px;color:#1f2937}
.tp-list button{display:flex;align-items:center;gap:10px;width:100%;border:0;background:none;padding:8px;border-radius:10px;text-align:left;color:#1f2937}
.tp-list button:hover{background:#f1f5f9}
.tp-list button.on{background:#eef2ff;font-weight:700}
.tp-sw{display:inline-flex;border-radius:8px;overflow:hidden;border:1px solid #e5e7eb;flex-shrink:0}
.tp-sw i{width:14px;height:22px;display:block}

/* ---------- Biểu tượng SVG ---------- */
.i{display:inline-flex;width:18px;height:18px;vertical-align:-3px;flex-shrink:0}
.i svg{width:100%;height:100%}
.tile-ico svg{width:36px;height:36px}
.tb-phone{display:inline-flex;align-items:center;gap:6px}
.tb-phone .i{width:14px;height:14px}
.btn .i{width:18px;height:18px}
.share button,.share a{display:inline-flex;align-items:center;gap:6px}
.filter-btn{align-items:center;gap:6px}
.share .i,.filter-btn .i{width:16px;height:16px}
.empty .big{width:110px;height:116px;margin:0 auto 10px;color:var(--accent)}
.empty .big svg{width:100%;height:100%}

/* ---------- Hình minh hoạ đầu trang ---------- */
.hero-in{position:relative}
.hero-art{position:absolute;right:0;top:70px;width:310px;height:auto;pointer-events:none}
.hero{padding-bottom:100px}
.hero::after{display:none}
.hero h1,.hero p{position:relative;z-index:1}
.ha-soft{fill:color-mix(in srgb,var(--accent) 8%,transparent)}
.ha-ring{fill:none;stroke:color-mix(in srgb,var(--accent) 35%,transparent);stroke-width:6}
.ha-dot{fill:#facc15}
.ha-accent{fill:var(--accent)}
.ha-title{fill:#fff;font-weight:700;font-size:17px;letter-spacing:1px}
.ha-line{fill:#e2e8f0}
.ha-box{fill:color-mix(in srgb,var(--accent) 9%,#fff);stroke:color-mix(in srgb,var(--accent) 35%,#fff);stroke-width:1.5}
.ha-box2{fill:#f8fafc;stroke:#e2e8f0;stroke-width:1.5}
.ha-formula{fill:var(--navy-2);font-size:24px;font-weight:700;font-family:Cambria,"Times New Roman",serif;font-style:italic}
.ha-axis{stroke:#94a3b8;stroke-width:2;fill:none;stroke-linecap:round}
.ha-curve{stroke:var(--accent);stroke-width:4;fill:none;stroke-linecap:round}
.ha-ruler{fill:#facc15;opacity:.9}
.ha-tick{stroke:#a16207;stroke-width:2;stroke-linecap:round}
.ha-pencil{fill:#f97316}
.ha-eraser{fill:#fb7185}
.ha-sym{fill:var(--accent);font-size:30px;font-weight:700;font-family:Cambria,"Times New Roman",serif}
.ha-sym-sm{font-size:24px}
@media (max-width:1100px){.hero-art{width:260px;top:110px}}
@media (max-width:900px){.hero-art{display:none}.hero{padding-bottom:64px}}

/* ---------- Hình nền chìm (ảnh bìa Facebook) — phủ từ mép trên màn hình xuống hết phần đầu trang ----------
   --nen-chim: độ đậm (0 → 1)   --nen-mo: độ nhoè
   --nen-cao: chiều cao vùng ảnh (trang chủ / trang khác) */
body{position:relative;--nen-cao:640px}
body.trang-con{--nen-cao:340px}
body::before{content:"";position:absolute;left:0;right:0;top:0;height:var(--nen-cao);z-index:-1;pointer-events:none;
  background:url(../anh/anh-bia.jpg) center/cover no-repeat;opacity:var(--nen-chim,.16);
  filter:blur(var(--nen-mo,8px)) saturate(1.1);
  -webkit-mask-image:linear-gradient(180deg,#000 60%,transparent);mask-image:linear-gradient(180deg,#000 60%,transparent)}
/* các dải đầu trang trong suốt để thấy hình nền */
.topbar{background:transparent;border-bottom-color:rgba(15,23,42,.06)}
.header{background:rgba(255,255,255,.55);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}
.nav{background:transparent;border-color:rgba(15,23,42,.06)}
.hero{background:transparent;border-bottom:0}
.page-head{background:transparent;border-bottom:0}

@media (max-width:600px){.logo-text b{font-size:24px}.logo-text small{font-size:14px}.logo-mark{width:50px;height:50px}.hero-stats{gap:8px}.hero-stats>div{padding:5px 10px}.hero-stats b{font-size:16px}}

/* ---------- Màn hình rộng ---------- */
@media (min-width:1500px){.grid{grid-template-columns:repeat(5,1fr)}.grid.g3{grid-template-columns:repeat(4,1fr)}}

/* ---------- Trang chi tiết: ảnh vừa 1 màn hình + cột phụ ---------- */
.detail{grid-template-columns:minmax(0,1fr) 400px;padding-top:12px}
.viewer .main-img{display:flex;justify-content:center;background:var(--soft)}
.viewer .main-img img{width:auto;max-width:100%;height:auto;max-height:max(380px,calc(100vh - 285px));object-fit:contain;box-shadow:0 2px 12px rgba(15,23,42,.12)}
.viewer.has-thumbs .main-img img{max-height:max(340px,calc(100vh - 385px))}
.trang-con .page-head{padding:14px 0 4px}
.side-col{display:flex;flex-direction:column;gap:22px;min-width:0}

/* Tài liệu mới nhất */
.latest{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:16px 18px 6px}
.latest-h{margin:0 0 6px;padding:11px 14px;background:#f1f3f5;border-left:6px solid var(--accent);font-size:16px;font-weight:700;text-transform:uppercase;letter-spacing:.3px;color:var(--navy-2)}
.latest-item{display:flex;gap:14px;padding:14px 0;border-bottom:1px solid var(--line)}
.latest-item:last-child{border-bottom:0}
.latest-thumb{width:96px;height:122px;flex-shrink:0;border:1px solid #c9ced6;padding:3px;background:#fff;overflow:hidden}
.latest-thumb img{width:100%;height:100%;object-fit:cover;object-position:top}
.latest-thumb .ph{padding:6px}.latest-thumb .ph-t,.latest-thumb .ph-s{display:none}.latest-thumb .ph-ico{width:44px;height:44px;margin:0}.latest-thumb .ph-ico svg{width:30px;height:30px}
.latest-body{display:flex;flex-direction:column;gap:8px;min-width:0}
.latest-body b{font-size:15px;line-height:1.5;color:var(--ink);font-weight:700}
.latest-item:hover b{color:var(--hl)}
.latest-body small{display:inline-flex;align-items:center;gap:5px;color:var(--muted);font-size:14px}
.latest-body small .i{width:14px;height:14px}
@media (max-width:900px){.detail{grid-template-columns:1fr}.viewer .main-img img{max-height:none;width:100%}}

/* ---------- Trang phụ: đầu trang giữ toàn màn hình, phần nội dung thu về khung 1240px như trước ---------- */
.trang-con #app .container{max-width:1240px;padding-left:16px;padding-right:16px}
@media (min-width:1500px){.trang-con .grid{grid-template-columns:repeat(4,1fr)}.trang-con .grid.g3{grid-template-columns:repeat(3,1fr)}}
.latest-more{display:block;text-align:center;padding:12px 0 10px;font-weight:700;font-size:14px;color:var(--accent);border-top:1px solid var(--line)}
.latest-more:hover{text-decoration:underline}

/* ---------- Trang chi tiết: ô tải xuống gọn + tài liệu liên quan nằm ngang ---------- */
.detail{grid-template-columns:minmax(0,1fr) 350px;gap:24px}
.side-col .info{padding:16px 18px}
.side-col .info .card-cat{font-size:12px}
.side-col .info h1{font-size:19px;margin:4px 0 8px}
.side-col .info p{font-size:13.5px;margin:0 0 8px}
.side-col .tags{margin:8px 0 10px}
.side-col .tag{font-size:11px;padding:3px 8px}
.side-col .dl-list{gap:8px;margin:10px 0}
.side-col .dl-list .btn{padding:9px 14px;font-size:14px}
.side-col .meta-table{font-size:13px}
.side-col .meta-table td{padding:6px 0}
.side-col .share{margin-top:10px;gap:6px}
.side-col .share button,.side-col .share a{font-size:12px;padding:6px 9px}
.latest-row{margin-top:24px;padding:16px 18px 8px}
.latest-grid{display:grid;grid-template-columns:repeat(3,1fr);column-gap:24px}
.latest-row .latest-item{border-bottom:1px solid var(--line)}
@media (max-width:900px){.latest-grid{grid-template-columns:1fr}}
@media (min-width:601px) and (max-width:900px){.latest-grid{grid-template-columns:repeat(2,1fr)}}

/* ---------- Lớp → Chương → Bài ---------- */
.card-cat .kieu{display:inline-block;margin-left:4px;padding:1px 8px;border-radius:999px;background:color-mix(in srgb,var(--c) 12%,#fff);color:var(--c);font-weight:700;font-size:11px}
.tb-back{font-size:14px;font-weight:600;color:var(--accent);white-space:nowrap}
.tb-back:hover{text-decoration:underline}
.section.sm{padding:6px 0 18px}
.section.sm .sec-head h2{font-size:19px}
.section.sm.first{padding-top:0}

.ch-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px}
.ch-card{display:flex;gap:16px;align-items:stretch;background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:16px;border:1px solid transparent;transition:.2s}
.ch-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-h);border-color:color-mix(in srgb,var(--c) 35%,#fff)}
.ch-no{width:74px;flex-shrink:0;border-radius:12px;background:linear-gradient(160deg,var(--c),color-mix(in srgb,var(--c) 60%,#0f172a));color:#fff;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:10px 0}
.ch-no small{font-size:11px;letter-spacing:.5px;text-transform:uppercase;opacity:.9}
.ch-no b{font-size:28px;line-height:1.1;font-family:Cambria,"Times New Roman",serif}
.ch-body{display:flex;flex-direction:column;gap:4px;min-width:0}
.ch-body b{font-size:16px;line-height:1.35;color:var(--navy)}
.ch-body small{font-size:13px;color:var(--muted)}
.ch-body em{margin-top:auto;font-style:normal;font-size:13px;font-weight:700;color:var(--c)}
.ch-card.trong{opacity:.62}
.ch-card.trong .ch-no{background:#cbd5e1}

.ls-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.ls-card{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);overflow:hidden;display:flex;flex-direction:column;transition:.2s}
.ls-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-h)}
.ls-thumb{position:relative;aspect-ratio:4/3;background:var(--soft);overflow:hidden}
.ls-thumb img{width:100%;height:100%;object-fit:cover;object-position:top}
.ls-thumb .badge{position:absolute;top:10px;left:10px;background:var(--c);color:#fff;font-size:12px;font-weight:700;padding:4px 10px;border-radius:6px}
.ls-count{position:absolute;right:10px;bottom:10px;background:rgba(15,23,42,.75);color:#fff;font-size:12px;font-weight:600;padding:3px 9px;border-radius:999px}
.ls-ph{width:100%;height:100%;display:grid;place-items:center;color:color-mix(in srgb,var(--c) 45%,#fff)}
.ls-ph svg{width:64px;height:64px}
.ls-body{padding:12px 14px 14px;display:flex;flex-direction:column;gap:6px;flex:1}
.ls-body b{font-size:14.5px;line-height:1.4;color:var(--navy)}
.ls-body em{margin-top:auto;font-style:normal;font-size:13px;font-weight:700;color:var(--accent)}
.ls-card.trong{opacity:.6}
.ls-card.trong em{color:var(--muted);font-weight:500}

.prev-next{display:flex;justify-content:space-between;gap:16px;margin-top:26px}
.pn{display:flex;flex-direction:column;gap:2px;background:#fff;border:1px solid var(--line);border-radius:12px;padding:10px 16px;max-width:48%;transition:.2s}
.pn:hover{border-color:var(--accent)}
.pn small{font-size:12px;color:var(--muted)}
.pn b{font-size:14px;color:var(--navy);font-weight:600}
.pn.next{text-align:right;margin-left:auto}
@media (max-width:900px){.ch-grid{grid-template-columns:1fr}.ls-grid{grid-template-columns:repeat(2,1fr)}}
@media (max-width:600px){.ls-grid{grid-template-columns:1fr 1fr;gap:12px}.prev-next{flex-direction:column}.pn{max-width:none}}
.tag.tag-kieu{background:color-mix(in srgb,var(--c) 14%,#fff);color:var(--c);font-weight:700}

/* Ô số chương: vuông bo góc, màu xanh chủ đạo của web */
.ch-no{width:76px;height:76px;align-self:center;border-radius:16px;background:var(--accent);padding:0;box-shadow:0 4px 12px color-mix(in srgb,var(--accent) 30%,transparent)}
.ch-no small{font-size:10px}
.ch-no b{font-size:24px}

/* ---------- Trình xem slide: mũi tên trái / phải ---------- */
.main-wrap{position:relative}
.nav-arrow{position:absolute;top:50%;transform:translateY(-50%);width:46px;height:46px;border-radius:50%;border:0;background:rgba(255,255,255,.92);color:var(--navy);box-shadow:0 4px 14px rgba(15,23,42,.18);display:grid;place-items:center;transition:.15s;z-index:2}
.nav-arrow svg{width:24px;height:24px}
.nav-arrow.prev{left:12px}.nav-arrow.next{right:12px}
.nav-arrow:hover:not(:disabled){background:var(--accent);color:#fff}
.nav-arrow:disabled{opacity:.35;cursor:default}
.slide-count{position:absolute;left:50%;bottom:12px;transform:translateX(-50%);background:rgba(15,23,42,.72);color:#fff;font-size:13px;font-weight:600;padding:4px 12px;border-radius:999px;white-space:nowrap;z-index:2}
.thumbs{overflow-x:auto;padding-bottom:4px;scrollbar-width:thin}
.thumbs img{flex-shrink:0;width:96px;height:56px;object-fit:cover;object-position:center}
.thumb-lock{flex-shrink:0;width:96px;height:56px;border-radius:8px;border:2px dashed #cbd5e1;background:var(--soft);display:flex;align-items:center;justify-content:center;gap:4px;color:var(--muted);cursor:pointer}
.thumb-lock svg{width:20px;height:20px}.thumb-lock small{font-weight:700}
.thumb-lock.on{border-color:var(--accent);color:var(--accent)}
.preview-note{display:flex;align-items:center;gap:6px;flex-wrap:wrap;margin:10px 2px 0;font-size:13.5px;color:var(--text-2)}
.preview-note .i{width:16px;height:16px;color:var(--accent)}
.preview-note a{color:var(--accent);font-weight:600}
.lock-slide{width:min(100%,960px);aspect-ratio:16/9;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:10px;text-align:center;padding:24px;background:linear-gradient(160deg,#eff6ff,#f8fafc);border:2px dashed #bfdbfe;border-radius:12px;color:var(--text-2)}
.lock-slide b{font-size:20px;color:var(--navy)}
.lock-slide .btn{margin-top:6px}
.phi-ico{width:64px;height:64px;border-radius:18px;background:color-mix(in srgb,var(--accent) 12%,#fff);color:var(--accent);display:grid;place-items:center}
.phi-ico svg{width:38px;height:38px}

/* ---------- Thông báo tài liệu có phí ---------- */
.phi-box{padding:34px 30px 30px;text-align:center;max-width:520px;margin:0 auto;display:flex;flex-direction:column;align-items:center;gap:10px}
.phi-box h2{margin:6px 0 0;color:var(--navy);font-size:22px}
.phi-box p{margin:0;color:var(--text-2);line-height:1.7}
.phi-sdt{color:var(--accent);font-size:17px;white-space:nowrap}
.phi-btns{display:flex;flex-direction:column;gap:10px;width:100%;margin-top:10px}
.phi-btns .btn{justify-content:center}
#modal .modal-box:has(.phi-box){max-width:560px}
button.btn{cursor:pointer;font-family:inherit}

/* ---------- Số liệu lượt xem / tải ---------- */
.cm-left{display:inline-flex;align-items:center;gap:10px;flex-wrap:wrap}
.cm-stat{display:inline-flex;align-items:center;gap:3px;color:var(--muted)}
.cm-stat svg{width:14px;height:14px}