*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --bg:#05060f; --surface:#10122b; --surface2:#151833;
  --vio:#8b5cf6; --vio2:#6d28d9; --cyan:#22d3ee;
  --tx:#e8eaf6; --mut:#9aa0b5; --dim:#6b7189;
  --line:rgba(139,92,246,.20); --line2:rgba(255,255,255,.07);
  --green:#22c55e; --amber:#f59e0b;
}
html{background:var(--bg)}
body{
  background:radial-gradient(900px 460px at 78% -12%,rgba(139,92,246,.16),transparent 62%),
             radial-gradient(700px 380px at 8% 0%,rgba(34,211,238,.07),transparent 60%),var(--bg);
  background-attachment:fixed; color:var(--tx);
  font-family:'Be Vietnam Pro',system-ui,-apple-system,sans-serif; line-height:1.65;
  min-height:100vh; -webkit-font-smoothing:antialiased;
}
.hidden{display:none!important}
.view{min-height:100vh}
.wrap{max-width:760px;margin:0 auto;padding:18px 16px 60px}
a{color:inherit}

/* ĐĂNG NHẬP */
#view-login{display:flex;align-items:center;justify-content:center;min-height:100vh;padding:20px}
.login-box{width:100%;max-width:400px;background:var(--surface);border:1px solid var(--line);border-radius:18px;padding:32px 26px}
.brand{font-size:26px;font-weight:800;text-align:center}
.brand-sub{text-align:center;color:var(--mut);font-size:12.5px;margin-top:4px;margin-bottom:24px;letter-spacing:.3px}
.login-form label{display:block;font-size:12.5px;font-weight:600;color:var(--mut);margin:14px 0 6px}
select,input{width:100%;background:var(--surface2);border:1px solid var(--line2);border-radius:10px;padding:12px 14px;color:var(--tx);font-family:inherit;font-size:15px;outline:none}
select:focus,input:focus{border-color:var(--vio)}
.btn-main{width:100%;margin-top:20px;background:linear-gradient(135deg,var(--vio),var(--vio2));color:#fff;border:none;border-radius:11px;padding:14px;font-size:15px;font-weight:700;font-family:inherit;cursor:pointer}
.btn-main:active{transform:translateY(1px)}
.btn-ghost{background:transparent;border:1px solid var(--line2);color:var(--mut);border-radius:9px;padding:8px 14px;font-size:13px;font-weight:600;font-family:inherit;cursor:pointer}
.err{color:#fca5a5;font-size:13px;margin-top:12px;min-height:18px;text-align:center}
.login-note{font-size:11.5px;color:var(--dim);margin-top:18px;text-align:center;line-height:1.6}

/* TOPBAR */
.topbar{position:sticky;top:0;z-index:5;display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:13px 16px;background:rgba(8,10,24,.85);backdrop-filter:blur(10px);border-bottom:1px solid var(--line2)}
.me-name{font-size:15px;font-weight:700}
.me-bac{font-size:11.5px;color:#c4b5fd}
.lesson-badge{font-size:12px;color:var(--mut);font-weight:600}

/* TIẾN ĐỘ */
.prog-card{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:18px 20px;margin-bottom:22px}
.prog-top{display:flex;justify-content:space-between;font-weight:700;font-size:14px;margin-bottom:10px}
.prog-top span:last-child{color:var(--cyan)}
.prog-bar{height:10px;background:rgba(255,255,255,.06);border-radius:99px;overflow:hidden}
.prog-bar span{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--vio),var(--cyan));border-radius:99px;transition:width .5s}
.prog-sub{font-size:12px;color:var(--mut);margin-top:9px}

/* NHÓM BẬC */
.bac-group{margin-bottom:24px}
.bac-h{font-size:12px;font-weight:700;text-transform:uppercase;letter-spacing:.6px;color:var(--mut);margin-bottom:11px;padding-left:2px}

/* THẺ BÀI */
.lesson-card{display:flex;align-items:center;gap:13px;background:var(--surface);border:1px solid var(--line2);border-radius:14px;padding:15px 16px;margin-bottom:10px;transition:border-color .16s,transform .1s}
.lesson-card:not(.st-lock){cursor:pointer}
.lesson-card:not(.st-lock):active{transform:scale(.99)}
.lesson-card.st-open:hover,.lesson-card.st-done:hover{border-color:rgba(139,92,246,.4)}
.lesson-card.st-lock{opacity:.55}
.lc-ico{width:38px;height:38px;flex-shrink:0;border-radius:11px;display:flex;align-items:center;justify-content:center;font-size:17px;background:var(--surface2);border:1px solid var(--line2)}
.st-done .lc-ico{background:rgba(34,197,94,.14);border-color:rgba(34,197,94,.3);color:#86efac}
.st-open .lc-ico{background:var(--vio-soft,rgba(139,92,246,.14));border-color:rgba(139,92,246,.3)}
.lc-main{flex:1;min-width:0}
.lc-title{font-size:14.5px;font-weight:600;line-height:1.35}
.lc-code{font-size:10.5px;font-weight:700;color:#c4b5fd;background:rgba(139,92,246,.14);padding:2px 6px;border-radius:5px;margin-right:7px}
.lc-meta{font-size:11.5px;color:var(--mut);margin-top:3px}
.lc-soon{color:var(--amber)}
.lc-tag{flex-shrink:0;font-size:10.5px;font-weight:600;padding:3px 9px;border-radius:99px;white-space:nowrap}
.lc-tag.st-open{color:#c4b5fd;background:rgba(139,92,246,.12);border:1px solid rgba(139,92,246,.25)}
.lc-tag.st-done{color:#86efac;background:rgba(34,197,94,.1);border:1px solid rgba(34,197,94,.28)}
.lc-tag.st-lock{color:var(--dim);background:rgba(255,255,255,.04);border:1px solid var(--line2)}

/* XEM BÀI */
.lesson-title{font-size:22px;font-weight:800;line-height:1.3;margin:6px 0 18px}
.lesson-video{width:100%;border-radius:14px;background:#000;margin-bottom:20px;max-height:60vh}
.lesson-read{font-size:15px;line-height:1.75;color:#dfe2f2}
.lesson-read h2{font-size:18px;font-weight:700;color:var(--tx);margin:22px 0 10px}
.lesson-read p{margin:0 0 12px}
.lesson-read b{color:#fff}
.lesson-read ul{margin:0 0 14px;padding-left:20px}
.lesson-read li{margin-bottom:7px}
.lesson-read blockquote{border-left:3px solid var(--vio);background:rgba(139,92,246,.08);padding:11px 15px;border-radius:0 8px 8px 0;margin:0 0 14px;color:#e8eaf6;font-style:italic}
.lesson-read hr{border:none;border-top:1px solid var(--line2);margin:20px 0}
.lark-link{display:inline-block;margin-top:8px;color:#a78bfa;text-decoration:underline;font-size:13.5px;font-weight:600}
.soon{color:var(--amber)}
.lesson-actions{margin-top:30px}

/* TRẮC NGHIỆM */
.quiz-note{font-size:12px;color:var(--mut);margin-top:10px;text-align:center}
.quiz-pass{background:rgba(34,197,94,.1);border:1px solid rgba(34,197,94,.3);color:#86efac;border-radius:11px;padding:13px 16px;font-size:14px;font-weight:600;margin-bottom:14px}
.quiz-lock{background:rgba(245,158,11,.1);border:1px solid rgba(245,158,11,.3);color:#fbbf24;border-radius:11px;padding:13px 16px;font-size:13.5px;margin-bottom:14px;line-height:1.5}
.quiz-wrap{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:18px 18px 20px}
.quiz-h{font-size:14px;font-weight:700;margin-bottom:16px;color:var(--tx)}
.quiz-q{margin-bottom:18px}
.quiz-qt{font-size:14px;font-weight:600;margin-bottom:10px;line-height:1.45}
.quiz-opt{display:flex;align-items:center;gap:11px;padding:11px 14px;border:1px solid var(--line2);border-radius:10px;margin-bottom:8px;cursor:pointer;font-size:14px;transition:border-color .14s,background .14s}
.quiz-opt:hover{border-color:rgba(139,92,246,.4)}
.quiz-opt input{width:auto;flex-shrink:0;accent-color:var(--vio);margin:0}
.quiz-opt:has(input:checked){border-color:var(--vio);background:rgba(139,92,246,.1)}
.quiz-result{border-radius:12px;padding:16px;text-align:center;margin-bottom:14px;font-size:14px;line-height:1.5}
.quiz-result.pass{background:rgba(34,197,94,.1);border:1px solid rgba(34,197,94,.32);color:#bbf7d0}
.quiz-result.fail{background:rgba(245,158,11,.08);border:1px solid rgba(245,158,11,.28);color:#fcd9a0}
.qr-score{font-size:32px;font-weight:800;margin-bottom:4px}
.quiz-result.pass .qr-score{color:#4ade80}
.quiz-result.fail .qr-score{color:#fbbf24}
.lesson-actions .btn-ghost{margin-top:10px;width:100%}