/* ============ Trading Education — design system ============ */
:root {
  --bg: #0b0d10;
  --bg-elev: #12151b;
  --bg-card: #171b22;
  --bg-card-hover: #1c212b;
  --line: #262c37;
  --line-soft: #1e242e;
  --text: #e8eaee;
  --text-dim: #9aa3b2;
  --text-faint: #5f6a7a;
  --accent: #e8b64c;
  --accent-strong: #f5c968;
  --accent-ink: #1a1408;
  --danger: #e5635f;
  --ok: #4caf7d;
  --radius: 14px;
  --radius-sm: 9px;
  --font: ui-sans-serif, -apple-system, "SF Pro Display", "Segoe UI", Roboto, Inter, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --shadow: 0 12px 40px rgba(0, 0, 0, 0.45);
  --topbar-h: 60px;
  --sidebar-w: 320px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
.hidden { display: none !important; }
.muted { color: var(--text-faint); }
code { font-family: var(--mono); font-size: 0.9em; background: #00000033; padding: 2px 6px; border-radius: 5px; }

/* subtle grain + vignette backdrop */
body::before {
  content: "";
  position: fixed; inset: 0;
  background:
    radial-gradient(1200px 600px at 70% -10%, rgba(232, 182, 76, 0.05), transparent 60%),
    radial-gradient(900px 500px at 10% 110%, rgba(76, 130, 245, 0.05), transparent 60%);
  pointer-events: none;
  z-index: 0;
}
#login-view, #app-view { position: relative; z-index: 1; }

/* ============ LOGIN ============ */
.login-view {
  min-height: 100vh;
  display: flex; align-items: center; justify-content: center;
  padding: 24px;
}
.login-card {
  position: relative;
  width: min(420px, 100%);
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 44px 40px 36px;
  box-shadow: var(--shadow);
  animation: rise 0.5s cubic-bezier(0.22, 1, 0.36, 1);
}
@keyframes rise { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }
.login-brand { display: flex; align-items: center; gap: 14px; margin-bottom: 30px; }
.login-logo {
  width: 52px; height: 52px; border-radius: 14px;
  background: linear-gradient(135deg, var(--accent-strong), var(--accent));
  color: var(--accent-ink);
  font-weight: 800; font-size: 22px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 6px 20px rgba(232, 182, 76, 0.25);
}
.login-title { font-weight: 700; letter-spacing: 0.14em; font-size: 17px; }
.login-sub { color: var(--text-faint); letter-spacing: 0.3em; font-size: 10px; margin-top: 3px; }
.login-heading { font-size: 26px; font-weight: 700; letter-spacing: -0.02em; margin-bottom: 8px; }
.login-lead { color: var(--text-dim); font-size: 14.5px; line-height: 1.55; margin-bottom: 26px; }
.otp-row { display: flex; gap: 10px; }
.otp-input {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  font-family: var(--mono);
  font-size: 28px;
  letter-spacing: 0.35em;
  text-align: center;
  padding: 12px 8px;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}
.otp-input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(232, 182, 76, 0.15); }
.otp-input.err { border-color: var(--danger); animation: shake 0.35s; }
@keyframes shake { 25% { transform: translateX(-5px); } 75% { transform: translateX(5px); } }
.btn {
  font-family: var(--font);
  font-size: 14.5px; font-weight: 600;
  border-radius: 10px;
  padding: 12px 20px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.1s, filter 0.15s, background 0.15s;
}
.btn:active { transform: scale(0.98); }
.btn-primary {
  background: linear-gradient(135deg, var(--accent-strong), var(--accent));
  color: var(--accent-ink);
  padding-inline: 26px;
}
.btn-primary:hover { filter: brightness(1.07); }
.btn-ghost {
  background: transparent; color: var(--text-dim);
  border-color: var(--line); font-size: 13px; padding: 8px 16px;
}
.btn-ghost:hover { color: var(--text); border-color: #3a4352; }
.login-error {
  margin-top: 12px; color: var(--danger); font-size: 13.5px;
  background: rgba(229, 99, 95, 0.08); border: 1px solid rgba(229, 99, 95, 0.25);
  border-radius: 8px; padding: 9px 12px;
}
.otp-timer {
  margin-top: 24px; padding-top: 18px;
  border-top: 1px solid var(--line-soft);
  display: flex; align-items: baseline; justify-content: space-between;
}
.timer-label { color: var(--text-faint); font-size: 12.5px; letter-spacing: 0.06em; text-transform: uppercase; }
.timer-value { font-family: var(--mono); color: var(--accent-strong); font-size: 17px; font-weight: 600; }
.login-hint { margin-top: 14px; color: var(--text-faint); font-size: 12px; line-height: 1.6; }
.login-bg-mark {
  position: fixed; right: -60px; bottom: -120px; z-index: -1;
  font-size: 480px; font-weight: 800; color: transparent;
  -webkit-text-stroke: 1px rgba(232, 182, 76, 0.07);
  pointer-events: none; user-select: none;
}

/* ============ TOPBAR ============ */
.topbar {
  position: sticky; top: 0; z-index: 40;
  height: var(--topbar-h);
  display: flex; align-items: center; gap: 14px;
  padding: 0 18px;
  background: rgba(11, 13, 16, 0.85);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line-soft);
}
.icon-btn {
  background: transparent; border: 1px solid var(--line); color: var(--text-dim);
  width: 38px; height: 38px; border-radius: 10px;
  display: none; align-items: center; justify-content: center; cursor: pointer;
}
.icon-btn:hover { color: var(--text); border-color: #3a4352; }
.topbar-brand { display: flex; align-items: center; gap: 11px; }
.topbar-logo {
  width: 32px; height: 32px; border-radius: 9px;
  background: linear-gradient(135deg, var(--accent-strong), var(--accent));
  color: var(--accent-ink); font-weight: 800; font-size: 13px;
  display: flex; align-items: center; justify-content: center;
}
.topbar-name { font-weight: 650; font-size: 15.5px; letter-spacing: -0.01em; }
.topbar-right { margin-left: auto; display: flex; align-items: center; gap: 14px; }
.session-timer { font-family: var(--mono); font-size: 12px; color: var(--text-faint); }

/* ============ LAYOUT ============ */
.layout { display: flex; min-height: calc(100vh - var(--topbar-h)); }
.sidebar {
  width: var(--sidebar-w); flex-shrink: 0;
  border-right: 1px solid var(--line-soft);
  background: var(--bg-elev);
  overflow-y: auto;
  max-height: calc(100vh - var(--topbar-h));
  position: sticky; top: var(--topbar-h);
  padding: 16px 12px 60px;
}
.sidebar-foot {
  margin-top: 18px; padding: 14px 12px 0;
  border-top: 1px solid var(--line-soft);
  color: var(--text-dim); font-size: 12px; line-height: 1.6;
}
.course-nav { display: flex; flex-direction: column; gap: 2px; }

/* --- education switcher (sidebar top) --- */
.edu-switcher {
  padding: 4px 6px 12px;
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: 10px;
}
.edu-label {
  display: block;
  font-size: 10px; font-weight: 700;
  letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 6px 6px;
}
.edu-current {
  width: 100%;
  display: flex; align-items: center; justify-content: space-between; gap: 8px;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  font-family: var(--font); font-size: 13.5px; font-weight: 600;
  padding: 10px 12px;
  cursor: pointer;
  transition: border-color 0.14s, color 0.14s;
}
.edu-current:hover { border-color: var(--accent); color: var(--accent-strong); }
.edu-current svg { color: var(--text-faint); flex-shrink: 0; }
.edu-current:hover svg { color: var(--accent-strong); }

/* --- education picker (home) --- */
.edu-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 16px; }
.edu-card {
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 20px;
  cursor: pointer;
  transition: transform 0.16s, border-color 0.16s, box-shadow 0.16s;
}
.edu-card:hover { transform: translateY(-3px); border-color: #333d4d; box-shadow: var(--shadow); }
.edu-card-head { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.edu-card-name { font-size: 17px; font-weight: 700; letter-spacing: -0.01em; }
.edu-card-meta {
  display: flex; gap: 18px;
  color: var(--text-dim); font-size: 12.5px;
}
.edu-card-meta span { font-family: var(--mono); }

/* --- accordion group --- */
.nav-group { border: 1px solid transparent; border-radius: 10px; }
.nav-group.open { border-color: var(--line-soft); background: rgba(255, 255, 255, 0.015); }

.nav-parent {
  display: flex; align-items: center; gap: 10px;
  padding: 9px 11px; border-radius: 9px;
  color: var(--text-dim); text-decoration: none;
  font-size: 13.5px; line-height: 1.3;
  cursor: pointer;
  transition: background 0.12s, color 0.12s;
  user-select: none;
}
.nav-parent:hover { background: var(--bg-card); color: var(--text); }
.nav-parent.active { background: var(--bg-card-hover); color: var(--accent-strong); }
.nav-parent .nav-num {
  font-family: var(--mono); font-size: 10.5px; color: var(--text-faint);
  width: 22px; flex-shrink: 0; text-align: right;
}
.nav-parent.locked .nav-num::after { content: " 🔒"; font-size: 9px; }
.nav-parent .nav-title { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nav-parent .nav-count { font-family: var(--mono); font-size: 10.5px; color: var(--text-faint); flex-shrink: 0; }
.nav-chevron {
  flex-shrink: 0; color: var(--text-faint);
  transition: transform 0.2s cubic-bezier(0.22, 1, 0.36, 1);
}
.nav-group.open .nav-chevron { transform: rotate(90deg); color: var(--accent-strong); }

/* --- children (lessons) --- */
.nav-children {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}
.nav-children-inner { overflow: hidden; min-height: 0; }
.nav-group.open .nav-children { grid-template-rows: 1fr; }
.nav-child {
  display: flex; align-items: center; gap: 9px;
  padding: 7px 11px 7px 44px;
  color: var(--text-faint); text-decoration: none;
  font-size: 12.5px; line-height: 1.35;
  border-radius: 7px;
  cursor: pointer;
  transition: background 0.12s, color 0.12s;
}
.nav-child:hover { background: var(--bg-card); color: var(--text-dim); }
.nav-child.active { background: rgba(232, 182, 76, 0.09); color: var(--accent-strong); }
.nav-child.locked .child-title { opacity: 0.55; }
.nav-child .child-num {
  font-family: var(--mono); font-size: 9.5px; color: var(--text-faint);
  width: 16px; flex-shrink: 0; text-align: right;
}
.nav-child .child-title { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nav-child .child-tag {
  font-size: 9px; font-weight: 650; letter-spacing: 0.05em; text-transform: uppercase;
  color: var(--text-faint); flex-shrink: 0;
}
/* --- section (set) headers in nav --- */
.nav-section {
  padding: 10px 11px 4px 44px;
  font-size: 10.5px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--text-faint);
  user-select: none;
}
.nav-section.sub { padding-left: 60px; }
.nav-section:first-child { padding-top: 8px; }
.nav-section + .nav-section { padding-top: 12px; }

/* ============ MAIN ============ */
.main {
  flex: 1; min-width: 0;
  padding: 30px 38px 80px;
  max-width: 1080px;
}

/* --- home hero + grid --- */
.hero { margin-bottom: 30px; }
.hero h1 { font-size: 30px; font-weight: 750; letter-spacing: -0.02em; }
.hero .hero-sub { color: var(--text-dim); margin-top: 6px; font-size: 14.5px; }
.hero-stats { display: flex; gap: 26px; margin-top: 18px; }
.stat .stat-num { font-size: 22px; font-weight: 750; font-family: var(--mono); color: var(--accent-strong); }
.stat .stat-label { font-size: 11.5px; color: var(--text-faint); text-transform: uppercase; letter-spacing: 0.08em; margin-top: 2px; }

.course-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 16px; }
.course-card {
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.16s, border-color 0.16s, box-shadow 0.16s;
  display: flex; flex-direction: column;
}
.course-card:hover { transform: translateY(-3px); border-color: #333d4d; box-shadow: var(--shadow); }
.course-card.cover { }
.card-cover { position: relative; aspect-ratio: 16/9; background: var(--bg); overflow: hidden; }
.card-cover img { width: 100%; height: 100%; object-fit: cover; }
.card-cover::after {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(180deg, transparent 40%, rgba(11, 13, 16, 0.9));
}
.card-cover .card-badge {
  position: absolute; top: 12px; left: 12px; z-index: 2;
  background: rgba(11, 13, 16, 0.72); backdrop-filter: blur(6px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--text); font-size: 10.5px; font-weight: 650;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 4px 9px; border-radius: 6px;
}
.card-cover .card-badge.locked { color: var(--danger); border-color: rgba(229, 99, 95, 0.35); }
.card-body { padding: 15px 16px 16px; display: flex; flex-direction: column; gap: 7px; flex: 1; }
.card-title { font-size: 15.5px; font-weight: 650; line-height: 1.35; }
.card-desc {
  color: var(--text-dim); font-size: 12.5px; line-height: 1.5;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.card-meta { margin-top: auto; padding-top: 8px; display: flex; justify-content: space-between; align-items: center; color: var(--text-faint); font-size: 11.5px; }
.card-meta .lessons { font-family: var(--mono); }

/* --- course detail --- */
.course-head { margin-bottom: 26px; }
.crumb { color: var(--text-faint); font-size: 12.5px; margin-bottom: 12px; cursor: pointer; }
.crumb:hover { color: var(--text-dim); }
.course-head h1 { font-size: 27px; font-weight: 750; letter-spacing: -0.02em; }
.course-head .course-meta-row { display: flex; gap: 16px; margin-top: 10px; color: var(--text-faint); font-size: 12.5px; align-items: center; }
.course-head .course-meta-row .lock-tag { color: var(--danger); }
.course-desc { margin-top: 12px; color: var(--text-dim); font-size: 14px; line-height: 1.6; max-width: 760px; }

.lesson-list { display: flex; flex-direction: column; gap: 10px; }
.lesson-section {
  margin: 14px 0 2px;
  font-size: 11px; font-weight: 700;
  letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--text-faint);
  display: flex; align-items: center; gap: 10px;
}
.lesson-section::after { content: ""; flex: 1; height: 1px; background: var(--line-soft); }
.lesson-section:first-child { margin-top: 0; }
.lesson-item {
  display: flex; align-items: center; gap: 14px;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  cursor: pointer;
  transition: border-color 0.14s, transform 0.14s, background 0.14s;
}
.lesson-item:hover { border-color: #333d4d; transform: translateX(2px); }
.lesson-item.active { border-color: var(--accent); background: var(--bg-card-hover); }
.lesson-num {
  font-family: var(--mono); font-size: 12px; color: var(--accent-strong);
  width: 30px; flex-shrink: 0; text-align: center;
  background: rgba(232, 182, 76, 0.08); border-radius: 7px; padding: 5px 0;
}
.lesson-body { flex: 1; min-width: 0; }
.lesson-title { font-size: 14.5px; font-weight: 600; line-height: 1.35; }
.lesson-sub { color: var(--text-faint); font-size: 12px; margin-top: 3px; }
.lesson-item.locked .lesson-title { color: var(--text-faint); }
.lesson-item.locked .lesson-num { color: var(--text-faint); background: rgba(255,255,255,0.04); }
.lesson-lock { color: var(--danger); font-size: 13px; flex-shrink: 0; }

/* --- lesson view --- */
.lesson-view { }
.lesson-view .back { color: var(--text-faint); font-size: 13px; cursor: pointer; margin-bottom: 16px; display: inline-block; }
.lesson-view .back:hover { color: var(--text-dim); }
.lesson-view h1 { font-size: 24px; font-weight: 750; letter-spacing: -0.02em; margin-bottom: 4px; }
.lesson-view .lesson-dur { color: var(--text-faint); font-size: 12.5px; font-family: var(--mono); margin-bottom: 20px; }

.player-frame {
  position: relative;
  aspect-ratio: 16/9;
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  margin-bottom: 24px;
}
.player-frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.player-frame .player-fallback {
  position: absolute; inset: 0; display: flex; flex-direction: column;
  align-items: center; justify-content: center; gap: 12px; color: var(--text-dim);
  background: linear-gradient(180deg, #10131a, #0b0d10); text-align: center; padding: 24px;
}
.player-frame .player-fallback a { color: var(--accent-strong); }

.cast-row { display: flex; margin: -14px 0 16px; }
.cast-btn {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--bg-elev); color: var(--text-dim);
  border: 1px solid var(--line); border-radius: 10px;
  padding: 9px 16px; font-family: var(--font); font-size: 13px; font-weight: 600;
  cursor: pointer; text-decoration: none;
  transition: color 0.14s, border-color 0.14s, background 0.14s;
}
.cast-btn:hover { color: var(--accent-strong); border-color: var(--accent); }
.cast-btn.active { background: rgba(232, 182, 76, 0.12); border-color: var(--accent); color: var(--accent-strong); }
.cast-btn.cast-note { cursor: pointer; }
.cast-label { letter-spacing: 0.02em; }
.cast-hint {
  font-size: 11.5px; color: var(--text-faint);
  line-height: 1.5; max-width: 520px;
  margin-left: 2px;
}

.source-box {
  display: flex; flex-wrap: wrap; align-items: center; gap: 8px;
  background: var(--bg-elev); border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm); padding: 12px 14px; margin-bottom: 26px;
}
.source-box .src-label { font-size: 11px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--text-faint); margin-right: 4px; }
.source-box .src-link {
  font-family: var(--mono); font-size: 12px; color: var(--text-dim);
  text-decoration: none; border: 1px solid var(--line); border-radius: 7px;
  padding: 5px 10px; transition: color 0.12s, border-color 0.12s;
}
.source-box .src-link:hover { color: var(--accent-strong); border-color: var(--accent); }
.src-tag { font-size: 10px; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; padding: 2px 6px; border-radius: 4px; background: rgba(255,255,255,0.06); color: var(--text-dim); }

.lesson-content { max-width: 780px; }
.lesson-content h1, .lesson-content h2, .lesson-content h3, .lesson-content h4 {
  margin: 1.4em 0 0.5em; font-weight: 700; letter-spacing: -0.01em; line-height: 1.3;
}
.lesson-content h1 { font-size: 20px; } .lesson-content h2 { font-size: 18px; } .lesson-content h3 { font-size: 16px; } .lesson-content h4 { font-size: 14.5px; }
.lesson-content p { margin: 0.75em 0; line-height: 1.65; color: #d6dae2; font-size: 14.5px; }
.lesson-content a { color: var(--accent-strong); text-decoration: none; border-bottom: 1px solid rgba(232, 182, 76, 0.3); }
.lesson-content a:hover { border-bottom-color: var(--accent-strong); }
.lesson-content ul, .lesson-content ol { margin: 0.8em 0; padding-left: 1.4em; line-height: 1.65; color: #d6dae2; font-size: 14.5px; }
.lesson-content li { margin: 0.35em 0; }
.lesson-content img { max-width: 100%; border-radius: 10px; margin: 0.8em 0; border: 1px solid var(--line); }
.lesson-content blockquote {
  border-left: 3px solid var(--accent); margin: 1em 0; padding: 6px 16px;
  color: var(--text-dim); background: rgba(232, 182, 76, 0.04); border-radius: 0 8px 8px 0;
}
.lesson-content hr { border: none; border-top: 1px solid var(--line-soft); margin: 1.6em 0; }

/* resources */
.resources { margin-top: 34px; }
.resources h2 { font-size: 15px; font-weight: 700; letter-spacing: 0.02em; margin-bottom: 14px; display: flex; align-items: center; gap: 8px; }
.resources h2::after { content: ""; flex: 1; height: 1px; background: var(--line-soft); }
.res-list { display: flex; flex-direction: column; gap: 8px; }
.res-item {
  display: flex; align-items: center; gap: 12px;
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius-sm); padding: 12px 14px;
  text-decoration: none; color: var(--text);
  transition: border-color 0.14s, transform 0.14s;
}
.res-item:hover { border-color: #333d4d; transform: translateX(2px); }
.res-icon {
  width: 36px; height: 36px; border-radius: 8px; flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 800; letter-spacing: 0.02em;
  background: rgba(232, 182, 76, 0.1); color: var(--accent-strong);
}
.res-name { flex: 1; font-size: 13.5px; font-weight: 550; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.res-type { color: var(--text-faint); font-size: 11px; font-family: var(--mono); flex-shrink: 0; }

.locked-panel {
  border: 1px dashed rgba(229, 99, 95, 0.4);
  border-radius: var(--radius);
  background: rgba(229, 99, 95, 0.05);
  padding: 34px; text-align: center; margin: 10px 0 24px;
}
.locked-panel .lock-emoji { font-size: 34px; }
.locked-panel h3 { margin: 12px 0 6px; font-size: 17px; }
.locked-panel p { color: var(--text-dim); font-size: 13.5px; line-height: 1.6; max-width: 420px; margin: 0 auto; }

.empty-state { text-align: center; padding: 70px 20px; color: var(--text-faint); }

/* ============ MOBILE ============ */
@media (max-width: 900px) {
  .icon-btn { display: flex; }
  .sidebar {
    position: fixed; top: var(--topbar-h); left: 0; bottom: 0;
    width: min(84vw, 340px);
    transform: translateX(-105%);
    transition: transform 0.25s cubic-bezier(0.22, 1, 0.36, 1);
    z-index: 50;
    max-height: none;
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: none; }
  .mobile-overlay {
    position: fixed; inset: 0; z-index: 45;
    background: rgba(0, 0, 0, 0.55);
    backdrop-filter: blur(2px);
  }
  .main { padding: 22px 18px 70px; }
  .course-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 24px; }
  .login-card { padding: 34px 24px 28px; }
  .otp-row { flex-direction: column; }
  .session-timer { display: none; }
}
@media (max-width: 480px) {
  .topbar-name { display: none; }
}