:root {
  --primary: #4f8ef7;
  --primary-dark: #3274df;
  --primary-light: #eef4ff;
  --success: #52c41a;
  --success-light: #f0faf0;
  --warning: #faad14;
  --warning-light: #fff7e6;
  --purple: #9b6fe8;
  --purple-light: #f5f0ff;
  --pink: #ff85c0;
  --pink-light: #fff0f6;
  --danger: #ff6b6b;
  --danger-light: #fff1f0;
  --text: #2c3e50;
  --text-secondary: #8795a1;
  --border: #eef0f5;
  --page-bg: #f7f8fc;
  --surface: #fff;
  --shadow-sm: 0 1px 3px rgba(79, 142, 247, .08);
  --shadow-md: 0 8px 24px rgba(34, 54, 84, .08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--text);
  background: var(--page-bg);
  font: 14px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
button, input, select, textarea { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { cursor: pointer; }
a { color: inherit; text-decoration: none; }
[hidden] { display: none !important; }

.app-shell { min-height: 100vh; }
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 20;
  width: 220px;
  padding: 20px 16px;
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border-right: 1px solid var(--border);
}
.brand {
  height: 52px;
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 0 8px;
}
.brand-mark {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  color: #fff;
  background: var(--primary);
  box-shadow: 0 6px 15px rgba(79,142,247,.24);
  font-weight: 800;
  font-size: 19px;
}
.brand strong, .brand small { display: block; }
.brand strong { font-size: 17px; letter-spacing: -.2px; }
.brand small { color: var(--text-secondary); font-size: 11px; }
.main-nav { margin-top: 24px; display: grid; gap: 6px; }
.main-nav a {
  min-height: 42px;
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 0 12px;
  color: #677482;
  border-radius: 9px;
  font-weight: 500;
  transition: background .18s, color .18s, transform .18s;
}
.main-nav a span { width: 20px; text-align: center; font-size: 17px; }
.main-nav a:hover { background: #fafbfe; color: var(--text); transform: translateX(1px); }
.main-nav a.active { color: var(--primary); background: var(--primary-light); font-weight: 650; }
.sidebar-status {
  margin-top: auto;
  padding: 13px 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  border-radius: 10px;
  color: #4d7752;
  background: var(--success-light);
  border: 1px solid #e5f4e5;
}
.sidebar-status strong, .sidebar-status small { display: block; }
.sidebar-status strong { font-size: 12px; }
.sidebar-status small { color: #7f9c83; font-size: 11px; }
.status-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--success); box-shadow: 0 0 0 4px rgba(82,196,26,.12); }
.sidebar-foot { margin: 14px 0 0; color: #b1bac4; font-size: 10px; text-align: center; }

.workspace { min-height: 100vh; margin-left: 220px; }
.topbar {
  position: sticky;
  top: 0;
  z-index: 15;
  height: 56px;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 24px;
  background: rgba(255,255,255,.94);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(10px);
}
.topbar-title { min-width: 0; }
.topbar-title strong { display: block; font-size: 15px; }
.topbar-title span { display: block; color: var(--text-secondary); font-size: 11px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.topbar-actions { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.utc-clock { color: var(--text-secondary); font: 12px ui-monospace, SFMono-Regular, Menlo, monospace; }
.signature-action, .soft-button, .primary-button, .danger-button, .icon-button {
  min-height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  border-radius: 8px;
  border: 1px solid transparent;
  font-weight: 600;
  transition: transform .18s, border-color .18s, box-shadow .18s;
}
.signature-action { padding: 0 14px; color: var(--primary); background: var(--primary-light); border-color: var(--primary-light); }
.signature-action.green { color: #58a931; background: var(--success-light); }
.signature-action.orange { color: #d48a0b; background: var(--warning-light); }
.signature-action.purple { color: var(--purple); background: var(--purple-light); }
.signature-action:hover, .soft-button:hover { transform: translateY(-1px); border-color: currentColor; box-shadow: var(--shadow-sm); }
.primary-button { min-height: 40px; padding: 0 18px; color: #fff; background: var(--primary); border-color: var(--primary); }
.primary-button:hover { background: var(--primary-dark); }
.primary-button:disabled, .signature-action:disabled { opacity: .5; cursor: not-allowed; transform: none; }
.soft-button { min-height: 38px; padding: 0 15px; color: var(--text); background: #fff; border-color: var(--border); }
.danger-button { min-height: 36px; padding: 0 14px; color: var(--danger); background: var(--danger-light); }
.icon-button { width: 36px; color: var(--text); background: #fff; border-color: var(--border); }
.mobile-menu { display: none; }

.main-content {
  width: min(1440px, calc(100% - 40px));
  min-height: calc(100vh - 96px);
  margin: 20px auto;
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
}
.page-heading { margin-bottom: 20px; display: flex; align-items: flex-start; gap: 16px; }
.page-heading h1 { margin: 0; font-size: 22px; letter-spacing: -.5px; }
.page-heading p { margin: 4px 0 0; color: var(--text-secondary); font-size: 13px; }
.page-actions { margin-left: auto; display: flex; gap: 8px; flex-wrap: wrap; justify-content: flex-end; }

.welcome-band {
  min-height: 142px;
  padding: 24px 26px;
  display: grid;
  grid-template-columns: 1.5fr .7fr;
  align-items: center;
  gap: 24px;
  border: 1px solid #e7eefc;
  border-radius: 14px;
  background: linear-gradient(110deg, #f9fbff 0%, #eef4ff 100%);
}
.eyebrow { margin: 0 0 7px; color: var(--primary); font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: .7px; }
.welcome-band h1 { margin: 0; font-size: clamp(24px, 3vw, 34px); letter-spacing: -1px; }
.welcome-band p { max-width: 620px; margin: 8px 0 17px; color: #6f7f91; }
.wave-readout {
  justify-self: end;
  width: min(100%, 330px);
  padding: 16px 18px;
  border-radius: 12px;
  background: rgba(255,255,255,.84);
  border: 1px solid rgba(79,142,247,.12);
}
.wave-line { height: 34px; display: flex; align-items: center; gap: 4px; overflow: hidden; }
.wave-line i { display: block; width: 3px; height: var(--h); border-radius: 3px; background: var(--primary); opacity: calc(.3 + var(--h) / 60); }
.wave-meta { margin-top: 8px; display: flex; justify-content: space-between; color: var(--text-secondary); font-size: 11px; }

.stat-grid { margin-top: 16px; display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.stat-card {
  position: relative;
  min-height: 108px;
  padding: 17px 18px 15px;
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent, var(--primary));
  border-radius: 12px;
  background: #fff;
}
.stat-card .stat-icon { position: absolute; top: 16px; right: 16px; width: 40px; height: 40px; display: grid; place-items: center; color: var(--accent); background: var(--accent-bg); border-radius: 10px; font-size: 18px; }
.stat-label { color: var(--text-secondary); font-size: 12px; }
.stat-value { margin: 4px 0 1px; font-size: 28px; line-height: 1.2; font-weight: 750; letter-spacing: -.8px; }
.stat-note { color: var(--text-secondary); font-size: 11px; }

.dashboard-grid { margin-top: 16px; display: grid; grid-template-columns: 1.35fr .65fr; gap: 16px; }
.panel { padding: 18px; border: 1px solid var(--border); border-radius: 12px; background: #fff; }
.panel-header { margin-bottom: 14px; display: flex; align-items: center; gap: 10px; }
.panel-header h2 { margin: 0; font-size: 15px; }
.panel-header p { margin: 2px 0 0; color: var(--text-secondary); font-size: 11px; }
.panel-header .panel-action { margin-left: auto; color: var(--primary); font-size: 12px; font-weight: 600; }
.quick-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.quick-card {
  min-height: 102px;
  padding: 14px;
  text-align: left;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #fff;
  transition: transform .18s, box-shadow .18s, border-color .18s;
}
.quick-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: #dce7fa; }
.quick-card .quick-icon { width: 34px; height: 34px; display: grid; place-items: center; margin-bottom: 10px; color: var(--color); background: var(--bg); border-radius: 9px; font-size: 16px; }
.quick-card strong { display: block; font-size: 13px; }
.quick-card small { color: var(--text-secondary); font-size: 10px; }
.exam-level-list { display: grid; gap: 10px; }
.level-row { padding: 13px; display: flex; align-items: center; gap: 12px; border: 1px solid var(--border); border-radius: 10px; }
.level-badge { width: 38px; height: 38px; display: grid; place-items: center; border-radius: 10px; color: var(--primary); background: var(--primary-light); font-weight: 800; }
.level-row:nth-child(2) .level-badge { color: var(--purple); background: var(--purple-light); }
.level-row:nth-child(3) .level-badge { color: #d48a0b; background: var(--warning-light); }
.level-row strong, .level-row small { display: block; }
.level-row small { color: var(--text-secondary); font-size: 10px; }
.level-row a { margin-left: auto; color: var(--primary); font-weight: 700; font-size: 12px; }

.filterbar { margin-bottom: 18px; display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.searchbox { min-width: min(100%, 320px); flex: 1; position: relative; }
.searchbox input, .form-field input, .form-field select, .form-field textarea, .select-control {
  width: 100%;
  min-height: 40px;
  padding: 9px 12px;
  color: var(--text);
  background: #fff;
  border: 1px solid #e4e8ef;
  border-radius: 8px;
  outline: none;
}
.searchbox input { padding-left: 36px; }
.searchbox span { position: absolute; left: 13px; top: 9px; color: var(--text-secondary); }
.searchbox input:focus, .form-field input:focus, .form-field select:focus, .form-field textarea:focus, .select-control:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79,142,247,.1); }
.chip-group { display: flex; gap: 7px; flex-wrap: wrap; }
.chip { min-height: 34px; padding: 0 12px; border-radius: 8px; color: #6f7c8b; background: #fafbfc; border: 1px solid var(--border); }
.chip.active { color: var(--primary); background: var(--primary-light); border-color: #dbe7ff; }
.tool-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.tool-card { min-height: 165px; padding: 17px; display: flex; flex-direction: column; border: 1px solid var(--border); border-radius: 12px; background: #fff; transition: .18s; }
.tool-card:hover { transform: translateY(-2px); border-color: #dfe8f7; box-shadow: var(--shadow-md); }
.tool-card-head { display: flex; align-items: center; justify-content: space-between; }
.tool-symbol { width: 40px; height: 40px; display: grid; place-items: center; color: var(--color); background: var(--bg); border-radius: 10px; font-size: 18px; }
.tool-tag { padding: 3px 7px; color: var(--text-secondary); background: #f7f8fa; border-radius: 6px; font-size: 10px; }
.tool-card h3 { margin: 13px 0 4px; font-size: 14px; }
.tool-card p { margin: 0 0 14px; color: var(--text-secondary); font-size: 11px; }
.tool-card button { margin-top: auto; align-self: flex-start; }
.empty-state { padding: 60px 20px; text-align: center; color: var(--text-secondary); }
.empty-state strong { display: block; color: var(--text); margin-bottom: 4px; }

.exam-setup { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.setup-panel { padding: 22px; border: 1px solid var(--border); border-radius: 12px; }
.setup-panel h2 { margin: 0 0 5px; font-size: 17px; }
.setup-panel > p { margin: 0 0 18px; color: var(--text-secondary); font-size: 12px; }
.level-options { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.level-option { padding: 15px 10px; text-align: center; border: 1px solid var(--border); border-radius: 10px; background: #fff; }
.level-option strong { display: block; font-size: 20px; }
.level-option small { color: var(--text-secondary); font-size: 10px; }
.level-option.active { color: var(--primary); background: var(--primary-light); border-color: #cfe0ff; }
.mode-options { display: grid; gap: 10px; }
.mode-option { padding: 15px; display: flex; align-items: center; gap: 12px; text-align: left; border: 1px solid var(--border); border-radius: 10px; background: #fff; }
.mode-option.active { border-color: #cfe0ff; background: #f9fbff; }
.mode-option span { width: 36px; height: 36px; display: grid; place-items: center; border-radius: 9px; color: var(--primary); background: var(--primary-light); }
.mode-option strong, .mode-option small { display: block; }
.mode-option small { color: var(--text-secondary); font-size: 10px; }
.exam-rules { margin: 16px 0; padding: 13px; display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; background: #fafbfc; border-radius: 10px; }
.exam-rules div { text-align: center; }
.exam-rules strong, .exam-rules small { display: block; }
.exam-rules strong { font-size: 15px; }
.exam-rules small { color: var(--text-secondary); font-size: 10px; }
.source-notice { margin-top: 16px; padding: 13px; color: #6d7784; background: var(--warning-light); border: 1px solid #ffedc9; border-radius: 9px; font-size: 11px; }

.exam-layout { display: grid; grid-template-columns: minmax(0, 1fr) 250px; gap: 16px; }
.exam-paper { min-height: 560px; padding: 24px; border: 1px solid var(--border); border-radius: 12px; }
.exam-progress { margin-bottom: 20px; display: flex; align-items: center; gap: 12px; }
.progress-track { height: 7px; flex: 1; background: #f0f2f6; border-radius: 8px; overflow: hidden; }
.progress-track i { display: block; height: 100%; width: var(--progress); background: var(--primary); border-radius: inherit; transition: width .2s; }
.question-type { display: inline-flex; padding: 4px 9px; color: var(--purple); background: var(--purple-light); border-radius: 7px; font-size: 11px; font-weight: 700; }
.question-title { margin: 15px 0 20px; font-size: 17px; line-height: 1.8; }
.answer-list { display: grid; gap: 10px; }
.answer-option { position: relative; min-height: 52px; padding: 13px 14px 13px 48px; display: flex; align-items: center; border: 1px solid var(--border); border-radius: 10px; cursor: pointer; transition: .18s; }
.answer-option:hover { border-color: #cbdcfb; background: #fbfdff; }
.answer-option.selected { border-color: var(--primary); background: var(--primary-light); }
.answer-letter { position: absolute; left: 13px; width: 25px; height: 25px; display: grid; place-items: center; border: 1px solid #dfe4ea; border-radius: 7px; color: #6e7b89; font-weight: 700; font-size: 12px; }
.answer-option.selected .answer-letter { color: #fff; background: var(--primary); border-color: var(--primary); }
.exam-footer { margin-top: 24px; display: flex; align-items: center; gap: 10px; }
.exam-footer .next { margin-left: auto; }
.exam-side { display: grid; gap: 12px; align-content: start; }
.timer-panel { padding: 16px; text-align: center; color: var(--primary); background: var(--primary-light); border: 1px solid #dfe9fc; border-radius: 12px; }
.timer-panel small { display: block; color: #7890b1; font-size: 10px; }
.timer-panel strong { font: 700 26px ui-monospace, SFMono-Regular, Menlo, monospace; }
.question-map { padding: 15px; border: 1px solid var(--border); border-radius: 12px; }
.question-map h3 { margin: 0 0 12px; font-size: 13px; }
.map-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; }
.map-item { aspect-ratio: 1; padding: 0; border: 1px solid var(--border); border-radius: 6px; background: #fff; color: var(--text-secondary); font-size: 10px; }
.map-item.answered { color: var(--primary); background: var(--primary-light); border-color: #d9e6ff; }
.map-item.current { color: #fff; background: var(--primary); border-color: var(--primary); }
.exam-legend { margin-top: 10px; display: flex; gap: 10px; color: var(--text-secondary); font-size: 9px; }

.result-hero { padding: 28px; text-align: center; border-radius: 14px; background: var(--primary-light); }
.result-hero.passed { background: var(--success-light); }
.result-score { margin: 5px 0; font-size: 52px; line-height: 1; font-weight: 800; letter-spacing: -2px; }
.result-hero p { margin: 8px 0 18px; color: var(--text-secondary); }
.result-summary { margin: 16px 0; display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.review-list { display: grid; gap: 10px; }
.review-item { padding: 14px; border: 1px solid var(--border); border-left: 3px solid var(--success); border-radius: 10px; }
.review-item.wrong { border-left-color: var(--danger); }
.review-item h4 { margin: 0 0 7px; font-size: 13px; }
.review-item p { margin: 3px 0; color: var(--text-secondary); font-size: 11px; }
.review-item .wrong-text { color: var(--danger); }
.review-item .right-text { color: var(--success); }

.reference-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.reference-card { padding: 18px; border: 1px solid var(--border); border-radius: 12px; }
.reference-card h3 { margin: 0 0 12px; font-size: 14px; }
.reference-list { display: grid; gap: 7px; }
.reference-row { padding: 8px 0; display: flex; justify-content: space-between; gap: 15px; border-bottom: 1px solid #f3f4f6; font-size: 11px; }
.reference-row:last-child { border-bottom: 0; }
.reference-row span:last-child { color: var(--text-secondary); text-align: right; }
.notice { padding: 13px 14px; color: #567091; background: var(--primary-light); border: 1px solid #dce8ff; border-radius: 9px; font-size: 11px; }

.profile-grid { display: grid; grid-template-columns: 300px 1fr; gap: 16px; }
.profile-card { padding: 22px; border: 1px solid var(--border); border-radius: 12px; text-align: center; }
.avatar { width: 72px; height: 72px; margin: 0 auto 12px; display: grid; place-items: center; color: #fff; background: var(--primary); border-radius: 18px; font-size: 26px; font-weight: 800; }
.profile-card h2 { margin: 0; }
.profile-card p { margin: 3px 0 16px; color: var(--text-secondary); }
.history-table, .admin-table { width: 100%; border-collapse: collapse; font-size: 12px; }
.history-table th, .admin-table th { padding: 10px; color: var(--text-secondary); background: #fafbfc; text-align: left; font-weight: 600; }
.history-table td, .admin-table td { padding: 11px 10px; border-bottom: 1px solid var(--border); }
.muted { color: var(--text-secondary); font-size: 10px; }
.call-sign { color: var(--primary); font: 700 13px ui-monospace, SFMono-Regular, Menlo, monospace; letter-spacing: .3px; }
.qso-table-wrap { overflow-x: auto; }
.qso-table { min-width: 880px; }
.row-actions { display: flex; align-items: center; gap: 6px; }
.row-actions .signature-action, .row-actions .danger-button { min-height: 30px; padding: 0 9px; font-size: 10px; }
.status-tag { display: inline-flex; padding: 3px 7px; border-radius: 6px; color: #4d9c2a; background: var(--success-light); font-size: 10px; }
.status-tag.fail, .status-tag.disabled { color: var(--danger); background: var(--danger-light); }
.status-tag.admin { color: var(--purple); background: var(--purple-light); }

.admin-tabs { margin-bottom: 16px; display: flex; gap: 8px; border-bottom: 1px solid var(--border); }
.admin-tab { padding: 9px 12px; color: var(--text-secondary); background: none; border: 0; border-bottom: 2px solid transparent; }
.admin-tab.active { color: var(--primary); border-bottom-color: var(--primary); }
.admin-content { overflow-x: auto; }

.modal-backdrop { position: fixed; inset: 0; z-index: 50; padding: 20px; display: grid; place-items: center; background: rgba(34,49,69,.38); backdrop-filter: blur(3px); }
.modal { width: min(100%, 520px); max-height: calc(100vh - 40px); overflow-y: auto; padding: 22px; background: #fff; border-radius: 14px; box-shadow: 0 24px 60px rgba(24,39,58,.2); }
.modal.wide { width: min(100%, 720px); }
.modal-header { margin-bottom: 18px; display: flex; align-items: flex-start; gap: 14px; }
.modal-header h2 { margin: 0; font-size: 18px; }
.modal-header p { margin: 3px 0 0; color: var(--text-secondary); font-size: 11px; }
.modal-header button { margin-left: auto; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 13px; }
.form-field { display: grid; gap: 6px; }
.form-field.full { grid-column: 1 / -1; }
.form-field label { font-size: 12px; font-weight: 600; }
.form-field small { color: var(--text-secondary); font-size: 10px; }
.form-field textarea { min-height: 90px; resize: vertical; }
.modal-actions { margin-top: 18px; display: flex; justify-content: flex-end; gap: 9px; }
.tool-result { margin-top: 16px; padding: 16px; color: var(--primary); background: var(--primary-light); border: 1px solid #dce8ff; border-radius: 10px; }
.tool-result strong { display: block; font-size: 22px; }
.auth-switch { margin-top: 14px; text-align: center; color: var(--text-secondary); font-size: 11px; }
.auth-switch button { padding: 0; color: var(--primary); background: none; border: 0; }

#toast-root { position: fixed; z-index: 80; right: 22px; top: 70px; display: grid; gap: 8px; }
.toast { min-width: 220px; max-width: 360px; padding: 11px 14px; color: #fff; background: #314158; border-radius: 9px; box-shadow: var(--shadow-md); animation: toast-in .2s ease; }
.toast.success { background: #4b9a30; }
.toast.error { background: #d95353; }
@keyframes toast-in { from { transform: translateY(-8px); opacity: 0; } }
.loading-state { min-height: 420px; display: grid; place-content: center; justify-items: center; color: var(--text-secondary); }
.spinner { width: 28px; height: 28px; border: 3px solid #e8edf5; border-top-color: var(--primary); border-radius: 50%; animation: spin .8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
.mobile-nav { display: none; }

@media (max-width: 1180px) {
  .tool-grid { grid-template-columns: repeat(3, 1fr); }
  .stat-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 900px) {
  .sidebar { transform: translateX(-100%); transition: transform .2s; box-shadow: var(--shadow-md); }
  .sidebar.open { transform: translateX(0); }
  .workspace { margin-left: 0; }
  .mobile-menu { display: inline-flex; }
  .main-content { width: calc(100% - 24px); margin: 12px auto 78px; padding: 18px; }
  .dashboard-grid, .profile-grid, .exam-setup, .exam-layout { grid-template-columns: 1fr; }
  .exam-side { grid-row: 1; grid-template-columns: 160px 1fr; }
  .tool-grid { grid-template-columns: repeat(2, 1fr); }
  .reference-grid { grid-template-columns: 1fr 1fr; }
  .mobile-nav {
    position: fixed;
    inset: auto 0 0 0;
    z-index: 30;
    height: 62px;
    padding: 5px max(10px, env(safe-area-inset-right)) calc(5px + env(safe-area-inset-bottom)) max(10px, env(safe-area-inset-left));
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    background: rgba(255,255,255,.97);
    border-top: 1px solid var(--border);
    backdrop-filter: blur(10px);
  }
  .mobile-nav a { display: grid; place-content: center; justify-items: center; color: var(--text-secondary); font-size: 10px; }
  .mobile-nav a span { font-size: 17px; line-height: 1.1; }
  .mobile-nav a.active { color: var(--primary); }
}
@media (max-width: 640px) {
  .topbar { padding: 0 12px; }
  .topbar-title span, .utc-clock, #auth-button span { display: none; }
  #auth-button { padding: 0 10px; font-size: 11px; }
  .main-content { padding: 14px; border-radius: 12px; }
  .welcome-band { padding: 19px; grid-template-columns: 1fr; }
  .wave-readout { display: none; }
  .welcome-band h1 { font-size: 25px; }
  .stat-grid { grid-template-columns: 1fr 1fr; gap: 10px; }
  .stat-card { min-height: 96px; padding: 14px; }
  .stat-card .stat-icon { display: none; }
  .stat-value { font-size: 23px; }
  .quick-grid { grid-template-columns: 1fr 1fr; }
  .tool-grid { grid-template-columns: 1fr; }
  .tool-card { min-height: 142px; }
  .reference-grid { grid-template-columns: 1fr; }
  .page-heading { display: block; }
  .page-actions { margin-top: 10px; justify-content: flex-start; }
  .level-options { gap: 6px; }
  .exam-rules { grid-template-columns: repeat(2, 1fr); }
  .exam-paper { padding: 16px; min-height: 480px; }
  .exam-side { grid-template-columns: 1fr; }
  .question-map { display: none; }
  .result-summary { grid-template-columns: repeat(2, 1fr); }
  .form-grid { grid-template-columns: 1fr; }
  .form-field.full { grid-column: auto; }
  .history-table th:nth-child(2), .history-table td:nth-child(2) { display: none; }
}