/* ─── DESIGN TOKENS — Emil Kowalski / Linear aesthetic ─── */
[data-theme="dark"] {
  --bg:         #09090b;
  --surface:    #111113;
  --card:       #18181b;
  --border:     #27272a;
  --border-hover: #3f3f46;
  --text:       #fafafa;
  --muted:      #71717a;
  --subtle:     #52525b;
  --accent:     #a78bfa;
  --accent-bg:  rgba(167,139,250,0.08);
  --accent-border: rgba(167,139,250,0.25);
  --primary:    #8b5cf6;
  --primary-bg: rgba(139,92,246,0.1);
  --green:      #34d399;
  --green-bg:   rgba(52,211,153,0.08);
  --yellow:     #fbbf24;
  --yellow-bg:  rgba(251,191,36,0.08);
  --red:        #f87171;
  --red-bg:     rgba(248,113,113,0.08);
  --code-bg:    #0c0c0e;
  --shadow-sm:  0 1px 2px rgba(0,0,0,0.4);
  --shadow:     0 4px 16px rgba(0,0,0,0.5);
  --shadow-lg:  0 8px 32px rgba(0,0,0,0.6);
}

[data-theme="light"] {
  --bg:         #ffffff;
  --surface:    #fafafa;
  --card:       #ffffff;
  --border:     #e4e4e7;
  --border-hover: #a1a1aa;
  --text:       #09090b;
  --muted:      #71717a;
  --subtle:     #a1a1aa;
  --accent:     #7c3aed;
  --accent-bg:  rgba(124,58,237,0.06);
  --accent-border: rgba(124,58,237,0.2);
  --primary:    #7c3aed;
  --primary-bg: rgba(124,58,237,0.06);
  --green:      #059669;
  --green-bg:   rgba(5,150,105,0.06);
  --yellow:     #d97706;
  --yellow-bg:  rgba(217,119,6,0.06);
  --red:        #dc2626;
  --red-bg:     rgba(220,38,38,0.06);
  --code-bg:    #f4f4f5;
  --shadow-sm:  0 1px 2px rgba(0,0,0,0.06);
  --shadow:     0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg:  0 8px 32px rgba(0,0,0,0.1);
}

/* ─── RESET ─── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ─── BASE ─── */
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background 0.2s, color 0.2s;
  font-size: 14px;
  line-height: 1.5;
}

/* ─── HEADER ─── */
header {
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px;
  height: 52px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
}

.logo {
  font-size: 0.8rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 7px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 5px 7px;
  border-radius: 8px;
  transition: background 0.15s;
  justify-self: start;
  color: var(--text);
  letter-spacing: -0.01em;
}

.logo:hover { background: var(--surface); }

.logo-mark {
  font-family: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  font-weight: 800;
  background: var(--accent);
  color: var(--bg);
  padding: 3px 6px;
  border-radius: 5px;
  letter-spacing: 0.04em;
  flex-shrink: 0;
}

[data-theme="light"] .logo-mark { color: #fff; }

.logo-name {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
}

/* ─── NAV TABS ─── */
.nav-tabs {
  display: flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 9px;
  padding: 3px;
  gap: 1px;
}

.tab {
  padding: 5px 14px;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.8rem;
  font-weight: 500;
  background: transparent;
  color: var(--muted);
  transition: all 0.15s;
  white-space: nowrap;
  letter-spacing: -0.01em;
}

.tab:hover:not(.active) { color: var(--text); }

.tab.active {
  background: var(--bg);
  color: var(--text);
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

/* ─── HEADER RIGHT ─── */
.header-right {
  display: flex;
  justify-content: flex-end;
  align-items: center;
}

.theme-toggle {
  width: 32px;
  height: 32px;
  border-radius: 7px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s;
}

.theme-toggle:hover {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border-hover);
}

/* ─── CONTAINER ─── */
.container { max-width: 1080px; margin: 0 auto; padding: 20px; }

/* ─── CONTROLS ─── */
.controls {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 6px;
  margin-bottom: 20px;
  align-items: center;
}

.filter-group {
  display: flex;
  gap: 4px;
  align-items: center;
  flex-wrap: nowrap;
  min-width: 0;
}

.search-wrap {
  position: relative;
  min-width: 200px;
}

.search-wrap svg {
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  pointer-events: none;
}

input[type="text"] {
  width: 100%;
  padding: 7px 10px 7px 32px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 7px;
  color: var(--text);
  font-size: 0.825rem;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
  font-family: inherit;
}

input[type="text"]:focus {
  border-color: var(--accent-border);
  box-shadow: 0 0 0 3px var(--accent-bg);
}

input[type="text"]::placeholder { color: var(--muted); }

.filter-btn {
  padding: 5px 11px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.775rem;
  font-weight: 500;
  transition: all 0.15s;
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  font-family: inherit;
  letter-spacing: -0.01em;
}

.filter-btn:hover:not(.active) {
  border-color: var(--border-hover);
  color: var(--text);
  background: var(--surface);
}

.filter-btn.active {
  border-color: var(--accent-border);
  color: var(--accent);
  background: var(--accent-bg);
}

/* ─── DROPDOWN ─── */
.dropdown-wrap { position: relative; }

.dropdown-trigger { gap: 2px; }

.dropdown-menu {
  display: none;
  position: absolute;
  top: calc(100% + 5px);
  left: 0;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 9px;
  padding: 4px;
  min-width: 140px;
  z-index: 200;
  box-shadow: var(--shadow);
  flex-direction: column;
  gap: 1px;
}

.dropdown-menu.open { display: flex; }

.dropdown-item {
  padding: 6px 10px;
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  border-radius: 6px;
  text-align: left;
  transition: all 0.12s;
  font-family: inherit;
  letter-spacing: -0.01em;
}

.dropdown-item:hover { background: var(--surface); color: var(--text); }
.dropdown-item.active { background: var(--accent-bg); color: var(--accent); font-weight: 600; }

.filter-count {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 16px;
  height: 15px;
  padding: 0 4px;
  border-radius: 4px;
  background: var(--border);
  color: var(--subtle);
  font-size: 0.6rem;
  font-weight: 600;
  margin-left: 4px;
  letter-spacing: 0;
  vertical-align: middle;
  transition: background 0.15s, color 0.15s;
}

.filter-btn.active .filter-count {
  background: var(--accent-border);
  color: var(--accent);
}

.dropdown-item.active .filter-count {
  background: var(--accent-border);
  color: var(--accent);
}

/* ─── CARDS GRID ─── */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 12px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
  cursor: default;
  position: relative;
}

.card:hover {
  border-color: var(--border-hover);
  box-shadow: var(--shadow);
  transform: translateY(-1px);
}

.card-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}

.cmd-badge {
  font-family: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 0.825rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-bg);
  padding: 3px 8px;
  border-radius: 5px;
  letter-spacing: 0.02em;
}

.category-tag {
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  padding: 2px 6px;
  border-radius: 4px;
  margin-left: auto;
}

.desc {
  font-size: 0.825rem;
  color: var(--muted);
  line-height: 1.6;
  margin-bottom: 12px;
}

.examples { display: flex; flex-direction: column; gap: 4px; }

.example {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 7px 10px;
  font-family: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 0.765rem;
  transition: border-color 0.12s;
}

.example:hover { border-color: var(--border-hover); }

.example .prompt { color: var(--subtle); user-select: none; flex-shrink: 0; }
.example .code   { color: var(--text); flex: 1; word-break: break-all; }
.example .comment { color: var(--muted); opacity: 0.6; }

.copy-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: 1px 4px;
  color: var(--muted);
  border-radius: 4px;
  transition: color 0.15s;
  flex-shrink: 0;
  line-height: 1;
}

.copy-btn:hover { color: var(--text); }
.copy-btn.copied { color: var(--green); }

/* ─── FAVOURITES ─── */
.fav-icon-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 5px 9px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.775rem;
  font-weight: 500;
  transition: all 0.15s;
  white-space: nowrap;
  flex-shrink: 0;
  font-family: inherit;
}

.fav-icon-btn:hover { border-color: var(--border-hover); color: var(--text); background: var(--surface); }
.fav-icon-btn.active {
  border-color: rgba(248,113,113,0.3);
  color: var(--red);
  background: var(--red-bg);
}

.fav-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: 3px 4px;
  border-radius: 5px;
  color: var(--muted);
  display: flex;
  align-items: center;
  transition: color 0.15s, background 0.15s;
  margin-left: 4px;
  flex-shrink: 0;
  line-height: 1;
}

.fav-btn:hover { color: var(--red); background: var(--red-bg); }
.fav-btn.is-fav { color: var(--red); }

@keyframes favPop {
  0%   { transform: scale(1); }
  35%  { transform: scale(1.5); }
  65%  { transform: scale(0.88); }
  85%  { transform: scale(1.1); }
  100% { transform: scale(1); }
}

.fav-btn.fav-pop .heart {
  animation: favPop 0.4s cubic-bezier(0.36, 0.07, 0.19, 0.97);
}

@keyframes cardLeave {
  0%   { opacity: 1; transform: scale(1); }
  100% { opacity: 0; transform: scale(0.94); }
}

.card-leaving {
  animation: cardLeave 0.2s ease;
  pointer-events: none;
}

.fav-filter-btn { gap: 4px; }

.fav-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 16px;
  height: 16px;
  padding: 0 4px;
  border-radius: 99px;
  background: var(--red);
  color: #fff;
  font-size: 0.62rem;
  font-weight: 700;
  margin-left: 4px;
  line-height: 1;
}

@keyframes badgeBump {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.4); }
  70%  { transform: scale(0.9); }
  100% { transform: scale(1); }
}

.fav-badge.badge-bump {
  animation: badgeBump 0.3s cubic-bezier(0.36, 0.07, 0.19, 0.97);
}

/* ─── CATEGORY COLORS ─── */
.cat-navigation  { background: rgba(167,139,250,0.08); color: #a78bfa; }
.cat-files       { background: rgba(52,211,153,0.08);  color: #34d399; }
.cat-viewing     { background: rgba(251,191,36,0.08);  color: #fbbf24; }
.cat-search      { background: rgba(248,113,113,0.08); color: #f87171; }
.cat-system      { background: rgba(167,139,250,0.08); color: #c4b5fd; }
.cat-network     { background: rgba(96,165,250,0.08);  color: #60a5fa; }
.cat-permissions { background: rgba(251,191,36,0.08);  color: #fbbf24; }
.cat-tools       { background: rgba(52,211,153,0.08);  color: #34d399; }
.cat-git         { background: rgba(248,113,113,0.08); color: #f87171; }

[data-theme="light"] .cat-navigation  { color: #7c3aed; background: rgba(124,58,237,0.06); }
[data-theme="light"] .cat-system      { color: #7c3aed; background: rgba(124,58,237,0.06); }
[data-theme="light"] .cat-network     { color: #1d4ed8; background: rgba(29,78,216,0.06); }
[data-theme="light"] .cat-files       { color: #059669; background: rgba(5,150,105,0.06); }
[data-theme="light"] .cat-tools       { color: #059669; background: rgba(5,150,105,0.06); }
[data-theme="light"] .cat-viewing     { color: #d97706; background: rgba(217,119,6,0.06); }
[data-theme="light"] .cat-permissions { color: #d97706; background: rgba(217,119,6,0.06); }
[data-theme="light"] .cat-search      { color: #dc2626; background: rgba(220,38,38,0.06); }
[data-theme="light"] .cat-git         { color: #dc2626; background: rgba(220,38,38,0.06); }

/* ─── MASTERED CARD ─── */
.card.mastered { border-color: rgba(52,211,153,0.25); }

/* Green heart on mastered cards (when not also a favourite) */
.card.mastered .fav-btn:not(.is-fav) {
  color: var(--green);
}

/* Tooltip on hover */
.card.mastered .fav-btn {
  position: relative;
}

.card.mastered .fav-btn::after {
  content: 'Mastered — answered correctly in quiz';
  position: absolute;
  bottom: calc(100% + 6px);
  right: 0;
  background: var(--card);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 0.7rem;
  font-weight: 500;
  font-family: inherit;
  padding: 5px 8px;
  border-radius: 6px;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.15s;
  box-shadow: var(--shadow);
  z-index: 10;
}

.card.mastered .fav-btn:hover::after { opacity: 1; }

/* ─── EMPTY STATE ─── */
.empty { text-align: center; padding: 60px 20px; color: var(--muted); }
.empty-icon { font-size: 2rem; margin-bottom: 10px; opacity: 0.5; }

/* ─── QUIZ ─── */
.quiz-wrap { display: none; }
.quiz-wrap.active { display: block; }

.quiz-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px 24px;
  text-align: center;
  box-shadow: var(--shadow);
}

.quiz-progress {
  display: flex;
  gap: 4px;
  justify-content: center;
  margin-bottom: 22px;
}

.dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--border);
  transition: background 0.25s;
}

.dot.correct { background: var(--green); }
.dot.wrong   { background: var(--red); }
.dot.current { background: var(--accent); }

.quiz-question {
  font-size: 0.825rem;
  color: var(--muted);
  margin-bottom: 6px;
  letter-spacing: -0.01em;
}

.quiz-cmd {
  font-family: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text);
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 14px 28px;
  border-radius: 10px;
  margin: 14px auto 24px;
  display: inline-block;
  letter-spacing: -0.01em;
}

.quiz-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-bottom: 18px;
}

.option-btn {
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface);
  color: var(--text);
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.15s;
  text-align: left;
  line-height: 1.45;
  font-family: inherit;
  letter-spacing: -0.01em;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--accent-border);
  background: var(--accent-bg);
}

.option-btn.correct {
  border-color: rgba(52,211,153,0.4);
  background: var(--green-bg);
  color: var(--green);
}

.option-btn.wrong {
  border-color: rgba(248,113,113,0.4);
  background: var(--red-bg);
  color: var(--red);
}

.option-btn:disabled { cursor: default; }

.quiz-feedback {
  font-size: 0.825rem;
  min-height: 22px;
  margin-bottom: 14px;
  color: var(--muted);
  letter-spacing: -0.01em;
}

.quiz-next {
  padding: 9px 28px;
  background: var(--accent);
  border: none;
  border-radius: 7px;
  color: #fff;
  font-weight: 600;
  font-size: 0.825rem;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.15s;
  display: none;
  font-family: inherit;
  letter-spacing: -0.01em;
}

.quiz-next:hover { opacity: 0.85; transform: translateY(-1px); }

.quiz-score {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text);
  margin: 14px 0 6px;
  letter-spacing: -0.03em;
}

.quiz-restart {
  padding: 9px 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 7px;
  color: var(--text);
  font-weight: 600;
  cursor: pointer;
  font-size: 0.825rem;
  margin-top: 14px;
  transition: all 0.15s;
  font-family: inherit;
  letter-spacing: -0.01em;
}

.quiz-restart:hover {
  border-color: var(--border-hover);
  background: var(--card);
  transform: translateY(-1px);
}

/* ─── CHEATSHEET ─── */
.cheatsheet-wrap { display: none; }
.cheatsheet-wrap.active { display: block; }

.cheat-section { margin-bottom: 24px; }

.cheat-title {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin-bottom: 8px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.cheat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 2px 16px;
}

.cheat-row {
  display: flex;
  gap: 10px;
  align-items: center;
  padding: 5px 8px;
  border-radius: 6px;
  transition: background 0.12s;
}

.cheat-row:hover { background: var(--surface); }

.cheat-cmd {
  font-family: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 0.765rem;
  color: var(--accent);
  white-space: nowrap;
  min-width: 100px;
}

.cheat-desc {
  font-size: 0.775rem;
  color: var(--muted);
  line-height: 1.45;
  flex: 1;
}

.cheat-copy-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: 2px 4px;
  color: var(--muted);
  border-radius: 4px;
  transition: color 0.15s, opacity 0.15s;
  opacity: 0;
  flex-shrink: 0;
  line-height: 1;
}

.cheat-row:hover .cheat-copy-btn { opacity: 1; }
.cheat-copy-btn:hover { color: var(--text); }
.cheat-copy-btn.copied { color: var(--green); opacity: 1; }

/* ─── GAMIFICATION HUD ─── */
.quiz-hud {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 14px;
}

.streak-badge {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--yellow);
  background: var(--yellow-bg);
  border: 1px solid rgba(251,191,36,0.2);
  padding: 4px 9px;
  border-radius: 7px;
  white-space: nowrap;
  letter-spacing: 0.01em;
}

.xp-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 12px;
  flex: 1;
}

#level-name {
  font-size: 0.7rem;
  font-weight: 700;
  white-space: nowrap;
  color: var(--accent);
  letter-spacing: -0.01em;
}

.xp-track {
  flex: 1;
  height: 3px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
  min-width: 36px;
}

.xp-fill {
  height: 100%;
  border-radius: 99px;
  background: var(--accent);
  transition: width 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.xp-num {
  font-size: 0.68rem;
  color: var(--muted);
  white-space: nowrap;
  letter-spacing: -0.01em;
}

/* XP feedback */
.xp-gain {
  color: var(--yellow);
  font-size: 0.78rem;
  font-weight: 700;
  margin-left: 6px;
}

.xp-bonus {
  color: var(--accent);
  font-size: 0.74rem;
  font-weight: 600;
  margin-left: 4px;
}

/* ─── PROGRESS SECTION ─── */
.progress-section {
  margin-top: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
}

.prog-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}

.prog-title {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.prog-overall {
  font-size: 0.7rem;
  color: var(--muted);
}

.prog-cats {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(170px, 1fr));
  gap: 6px 16px;
}

.prog-cat {
  display: flex;
  align-items: center;
  gap: 8px;
}

.prog-cat-name {
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--muted);
  text-transform: capitalize;
  min-width: 70px;
  letter-spacing: -0.01em;
}

.prog-bar {
  flex: 1;
  height: 3px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
}

.prog-fill {
  height: 100%;
  background: var(--green);
  border-radius: 99px;
  transition: width 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.prog-frac {
  font-size: 0.62rem;
  color: var(--subtle);
  min-width: 26px;
  text-align: right;
  letter-spacing: -0.01em;
}

/* ─── BROWSE MASTERY BAR ─── */
.browse-mastery {
  display: none;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 12px;
}

.browse-mastery-label {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  white-space: nowrap;
  flex-shrink: 0;
}

.browse-mastery-bar {
  flex: 1;
  height: 3px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
  min-width: 40px;
}

.browse-mastery-fill {
  height: 100%;
  background: var(--green);
  border-radius: 99px;
  transition: width 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.browse-mastery-frac {
  font-size: 0.68rem;
  color: var(--muted);
  white-space: nowrap;
  letter-spacing: -0.01em;
  flex-shrink: 0;
}

/* ─── ACHIEVEMENT GALLERY ─── */
.achievement-section {
  margin-top: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
}

.achiev-header {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin-bottom: 10px;
}

.achiev-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  gap: 8px;
}

.achiev-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 10px 8px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--card);
  text-align: center;
  transition: border-color 0.15s;
}

.achiev-item.unlocked { border-color: rgba(52,211,153,0.3); }
.achiev-item.locked   { opacity: 0.4; filter: grayscale(0.5); }

.achiev-icon  { font-size: 1.4rem; line-height: 1; }
.achiev-title { font-size: 0.7rem; font-weight: 700; color: var(--text); letter-spacing: -0.01em; }
.achiev-desc  { font-size: 0.62rem; color: var(--muted); line-height: 1.35; }

/* ─── TOASTS (Sonner-inspired) ─── */
#toast-container {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 9999;
  display: flex;
  flex-direction: column-reverse;
  gap: 6px;
  pointer-events: none;
}

.toast {
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 0.8rem;
  font-weight: 500;
  opacity: 0;
  transform: translateY(8px) scale(0.96);
  transition: opacity 0.2s, transform 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
  max-width: 260px;
  box-shadow: var(--shadow);
  line-height: 1.35;
  border: 1px solid var(--border);
  letter-spacing: -0.01em;
  color: var(--text);
  background: var(--card);
}

.toast-show {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.toast-xp {
  border-color: rgba(251,191,36,0.2);
}

.toast-level-up {
  border-color: var(--accent-border);
  color: var(--accent);
}

.toast-achievement {
  border-color: rgba(52,211,153,0.25);
  color: var(--green);
}

/* ─── QUIZ CONTROLS ─── */
.quiz-controls {
  margin-bottom: 12px;
  overflow: hidden;
}

.quiz-control-row {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: nowrap;
  min-width: 0;
  width: 100%;
}

.quiz-mode-group {
  display: flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 3px;
  gap: 2px;
  flex-shrink: 0;
}

.quiz-mode-btn {
  padding: 4px 12px;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 0.775rem;
  font-weight: 500;
  background: transparent;
  color: var(--muted);
  transition: all 0.15s;
  font-family: inherit;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

.quiz-mode-btn.active {
  background: var(--bg);
  color: var(--text);
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

.quiz-cat-btn.active {
  border-color: var(--accent-border);
  color: var(--accent);
  background: var(--accent-bg);
}

.quiz-mode-divider {
  width: 1px;
  height: 20px;
  background: var(--border);
  flex-shrink: 0;
}

/* ─── QUIZ OPTION NUMBERS & RECALL ─── */
.option-btn {
  display: flex;
  align-items: flex-start;
  gap: 8px;
}

.option-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  border-radius: 4px;
  background: var(--border);
  color: var(--subtle);
  font-size: 0.62rem;
  font-weight: 700;
  flex-shrink: 0;
  font-family: 'SF Mono', 'Fira Code', monospace;
  margin-top: 1px;
  transition: background 0.15s;
}

.option-btn:hover:not(:disabled) .option-num {
  background: var(--accent-border);
  color: var(--accent);
}

.option-btn.correct .option-num { background: rgba(52,211,153,0.25); color: var(--green); }
.option-btn.wrong .option-num   { background: rgba(248,113,113,0.2);  color: var(--red);   }

.opt-code {
  font-family: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent);
}

.quiz-desc-prompt {
  font-size: 0.875rem;
  color: var(--text);
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 14px 20px;
  border-radius: 10px;
  margin: 14px 0 24px;
  display: block;
  line-height: 1.6;
  text-align: left;
}

/* ─── KEYBOARD HINT ─── */
.kbd-hint {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-top: 10px;
  flex-wrap: wrap;
}

.kbd-hint-item {
  display: flex;
  align-items: center;
  gap: 3px;
  font-size: 0.68rem;
  color: var(--subtle);
}

.kbd-hint-item span { margin-left: 2px; }

kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 2px 5px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  font-family: 'SF Mono', 'Fira Code', monospace;
  font-size: 0.62rem;
  color: var(--text);
  box-shadow: 0 1px 0 var(--border);
  min-width: 18px;
  letter-spacing: 0;
}

/* ─── RESPONSIVE ─── */
@media (max-width: 680px) {
  .header-inner {
    grid-template-columns: 1fr auto;
    height: auto;
    padding: 10px 16px;
    row-gap: 10px;
  }

  .nav-tabs {
    grid-column: 1 / -1;
    justify-content: center;
    order: 3;
    margin: 0 -16px;
    border-radius: 0;
    border-left: none;
    border-right: none;
    border-top: none;
  }

  .header-right { grid-row: 1; grid-column: 2; }
  .tab { padding: 5px 10px; font-size: 0.775rem; }
  .quiz-options { grid-template-columns: 1fr; }
  .search-wrap { min-width: 120px; }
  .prog-cats { grid-template-columns: 1fr 1fr; }
}