:root{
  --navy:#1F3864; --blue:#2E5CB8; --sky:#4C8DFF; --cyan:#00C2D1;
  --bg:#EEF3FB; --card:#FFFFFF; --ink:#1A2233; --muted:#6B7793;
  --line:#E1E8F5; --ok:#1BA672; --bad:#E5484D; --elite:#F2711C; --eliteBg:#FFF3E9;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;padding:0}
body{font-family:"Segoe UI",Roboto,system-ui,-apple-system,Arial,sans-serif;background:var(--bg);color:var(--ink);line-height:1.5;overscroll-behavior:none}
.app{max-width:520px;margin:0 auto;min-height:100vh;background:var(--bg);display:flex;flex-direction:column}
/* top bar */
.appbar{background:linear-gradient(120deg,var(--navy),var(--blue));color:#fff;padding:14px 18px;display:flex;align-items:center;gap:12px;position:sticky;top:0;z-index:10}
.appbar .logo{width:38px;height:38px;border-radius:11px;background:linear-gradient(135deg,var(--cyan),var(--sky));display:flex;align-items:center;justify-content:center;font-weight:800;color:#04263a}
.appbar h1{font-size:16px;margin:0}
.appbar p{margin:1px 0 0;font-size:11.5px;opacity:.85}
.screen{flex:1;padding:18px}
.card{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:20px;box-shadow:0 8px 24px rgba(31,56,100,.08)}
h2{margin:0 0 4px;font-size:19px;color:var(--navy)}
.sub{color:var(--muted);font-size:13px;margin:0 0 16px}
label{display:block;font-weight:600;font-size:13px;margin:14px 0 6px}
input[type=text],select{width:100%;padding:13px;border:1.5px solid var(--line);border-radius:13px;font-size:16px;font-family:inherit;background:#fff}
input:focus,select:focus{outline:none;border-color:var(--sky)}
/* WIZARD stepbar */
.steps{display:flex;align-items:center;justify-content:space-between;padding:2px 4px 14px}
.stepdot{display:flex;flex-direction:column;align-items:center;gap:3px;font-size:10.5px;color:var(--muted);font-weight:600;flex:none}
.stepdot span{width:26px;height:26px;border-radius:50%;background:#fff;border:2px solid var(--line);display:flex;align-items:center;justify-content:center;font-size:12px;color:var(--muted)}
.stepdot.cur span{background:var(--blue);border-color:var(--blue);color:#fff}
.stepdot.cur{color:var(--blue)}
.stepdot.done span{background:#EAF1FB;border-color:var(--blue);color:var(--blue)}
.stepline{height:2px;background:var(--line);flex:1;margin:0 4px;transform:translateY(-8px)}
.wstep h2{margin-top:0}
/* Tier cards */
.tier-card{border:2px solid var(--line);border-radius:15px;padding:13px 15px;margin-bottom:10px;cursor:pointer;background:#fff;transition:.12s}
.tier-card:active{transform:scale(.995)}
.tier-card.sel{border-color:var(--blue);background:#EEF4FF}
.tier-card .tc-top{display:flex;align-items:center;gap:8px}
.tier-card .tc-top b{font-size:15px;color:var(--navy)}
.tier-card .g{font-size:12px;font-weight:700;color:#fff;background:linear-gradient(120deg,var(--blue),var(--sky));padding:2px 10px;border-radius:999px;margin-left:auto;white-space:nowrap}
.tier-card p{margin:6px 0 0;font-size:12.5px;color:var(--muted);line-height:1.45}
/* Course cards */
.course-card{padding:13px 15px;border:2px solid var(--line);border-radius:15px;margin-bottom:10px;cursor:pointer;background:#fff;transition:.1s}
.course-card:active{transform:scale(.995)}
.course-card.sel{border-color:var(--blue);background:#EEF4FF}
.course-card .cc-head{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.course-card .cc-head b{font-size:15.5px;color:var(--navy)}
.course-card .cc-head .en{font-size:12px;color:var(--muted);font-style:italic}
.course-card .cc-head .tick{margin-left:auto;width:22px;height:22px;flex:none;border-radius:50%;border:2px solid var(--line);display:flex;align-items:center;justify-content:center;color:#fff;font-size:13px}
.course-card.sel .cc-head .tick{background:var(--blue);border-color:var(--blue)}
.course-card .cc-need,.course-card .cc-learn{font-size:12px;line-height:1.5;margin-top:5px;color:var(--ink)}
.course-card .cc-need{color:#8a5a17} .course-card .cc-need b,.course-card .cc-learn b{color:var(--navy)}
/* Context bar (Tầng/khóa khi làm bài + kết quả) */
.ctxbar{background:linear-gradient(120deg,#EAF1FB,#F2F7FF);border-bottom:1px solid var(--line);padding:10px 16px}
.ctxbar.inline{border-radius:14px;border:1px solid var(--line);margin-bottom:12px}
.ctx-line{display:flex;align-items:center;gap:8px;font-size:12.5px;font-weight:600;color:var(--navy)}
.ctx-badge{font-size:10px;font-weight:800;background:var(--blue);color:#fff;padding:2px 8px;border-radius:999px;letter-spacing:.02em}
.ctx-g{font-weight:700;color:var(--blue)}
.ctx-course{font-size:12.5px;color:var(--ink);margin-top:3px} .ctx-course .en{font-style:italic;color:var(--muted);font-size:11.5px}
/* Language switch */
.langsw{margin-left:auto;display:flex;gap:0;border:1px solid rgba(255,255,255,.4);border-radius:999px;overflow:hidden}
.langsw button{background:transparent;color:#fff;border:none;padding:5px 11px;font-size:12px;font-weight:700;cursor:pointer}
.langsw button.on{background:#fff;color:var(--navy)}
.grouppick{display:flex;flex-direction:column;gap:10px;margin-top:6px}
.pick{border:2px solid var(--line);border-radius:15px;padding:14px 16px;cursor:pointer;background:#fff;transition:.12s}
.pick.sel{border-color:var(--blue);background:#EEF4FF}
.pick.elite.sel{border-color:var(--elite);background:var(--eliteBg)}
.pick b{display:block;font-size:15px}
.pick span{font-size:12.5px;color:var(--muted)}
.btn{width:100%;background:linear-gradient(120deg,var(--blue),var(--sky));color:#fff;border:none;padding:15px;border-radius:14px;font-size:16px;font-weight:700;cursor:pointer;box-shadow:0 8px 18px rgba(46,92,184,.28)}
.btn:active{transform:scale(.985)}
.btn.ghost{background:#fff;color:var(--blue);border:1.5px solid var(--line);box-shadow:none}
.btn.small{width:auto;padding:12px 20px;font-size:15px}
.btn:disabled{opacity:.45}
.badge{display:inline-block;font-size:11px;font-weight:700;padding:3px 10px;border-radius:999px;background:#EEF4FF;color:var(--blue)}
.badge.elite{background:var(--eliteBg);color:var(--elite)}
.err{color:var(--bad);font-size:13px;margin-top:10px;display:none}
.err.show{display:block}
.link{display:block;text-align:center;margin-top:16px;color:var(--muted);font-size:13px;text-decoration:none}
/* progress + timer */
.progwrap{position:sticky;top:66px;z-index:9;background:var(--bg);padding:12px 18px 6px}
.progtop{display:flex;justify-content:space-between;align-items:center;font-size:13px;font-weight:600;margin-bottom:8px}
.clock{font-variant-numeric:tabular-nums;background:#fff;border:1px solid var(--line);border-radius:999px;padding:4px 12px;color:var(--blue)}
.clock.warn{color:var(--bad);border-color:#F6C6C6}
.progbar{height:8px;background:#DCE6F7;border-radius:999px;overflow:hidden}
.progbar>div{height:100%;background:linear-gradient(90deg,var(--sky),var(--cyan));border-radius:999px;transition:width .25s}
/* question */
.qcard{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:20px;box-shadow:0 8px 24px rgba(31,56,100,.08);min-height:auto}
.qcard.elite{background:var(--eliteBg);border-color:#FADFC8}
.qtopbar{display:flex;align-items:center;gap:8px;margin-bottom:12px}
.qtopic{font-size:11px;color:var(--muted);background:#F0F3FA;padding:3px 9px;border-radius:7px;margin-left:auto}
.qtext{font-size:17px;font-weight:600;margin:0 0 6px;white-space:pre-wrap;line-height:1.45}
.viz{margin:10px 0 4px}
.opts{margin-top:12px;display:flex;flex-direction:column;gap:10px}
.opt{display:flex;gap:12px;align-items:flex-start;padding:14px;border:2px solid var(--line);border-radius:14px;cursor:pointer;background:#fff;transition:.1s;font-size:15.5px}
.opt:active{transform:scale(.99)}
.opt.sel{border-color:var(--blue);background:#EEF4FF}
.elite .opt.sel{border-color:var(--elite);background:#FFEEDE}
.opt .letter{width:26px;height:26px;flex:none;border-radius:50%;background:#EEF4FF;color:var(--blue);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:14px}
.opt.sel .letter{background:var(--blue);color:#fff}
.elite .opt.sel .letter{background:var(--elite)}
.navrow{display:flex;gap:12px;margin-top:18px}
.navrow .btn{flex:1}
.dots{display:flex;flex-wrap:wrap;gap:7px;justify-content:center;margin-top:16px}
.dot{width:26px;height:26px;border-radius:8px;border:1.5px solid var(--line);background:#fff;font-size:12px;color:var(--muted);cursor:pointer;display:flex;align-items:center;justify-content:center}
.dot.done{background:#EAF1FB;border-color:var(--blue);color:var(--blue);font-weight:700}
.dot.cur{background:var(--blue);border-color:var(--blue);color:#fff;font-weight:700}
/* result */
.scorebig{font-size:56px;font-weight:800;color:var(--blue);line-height:1;text-align:center}
.result-head{text-align:center;padding:6px 0}
.pill{display:inline-block;padding:9px 20px;border-radius:999px;font-weight:800;font-size:15px;margin-top:12px}
.pill.ok{background:#E4F7EF;color:var(--ok)} .pill.bad{background:#FDECEC;color:var(--bad)}
.kv{display:flex;justify-content:space-between;padding:12px 2px;border-bottom:1px solid var(--line);font-size:14.5px}
.kv b{color:var(--navy)}
.foot{text-align:center;color:var(--muted);font-size:11.5px;padding:16px}
.hidden{display:none}
.center{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:60vh;text-align:center;gap:12px}
@media (min-width:560px){.app{margin:16px auto;min-height:calc(100vh - 32px);border-radius:22px;overflow:hidden;box-shadow:0 20px 60px rgba(31,56,100,.14)}.appbar{border-radius:0}}