/* Quiz layout */
.quiz-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 0;
  min-height: calc(100vh - 57px);
}

/* Sidebar tree */
.quiz-sidebar {
  background: var(--bg-soft);
  border-right: 1px solid var(--border);
  padding: 24px 0;
  position: sticky;
  top: 57px;
  height: calc(100vh - 57px);
  overflow-y: auto;
}

.sidebar-title {
  color: var(--text-dim);
  font-size: 0.7rem;
  letter-spacing: 2px;
  padding: 0 20px 12px;
  text-transform: uppercase;
}

.tree-category {
  margin-bottom: 4px;
}

.tree-category-btn {
  width: 100%;
  background: none;
  border: none;
  color: var(--text);
  font-family: inherit;
  font-size: 0.9rem;
  padding: 8px 20px;
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}
.tree-category-btn:hover { background: var(--bg-card); color: var(--teal); }
.tree-category-btn .cat-icon { font-size: 0.75rem; color: var(--orange); }
.tree-category-btn .caret {
  font-size: 0.65rem;
  color: var(--text-dim);
  transition: transform 0.2s;
  flex-shrink: 0;
}
.tree-category-btn.open .caret { transform: rotate(90deg); }
.tree-category-btn .badge {
  font-size: 0.6rem;
  background: var(--border);
  color: var(--text-dim);
  padding: 1px 6px;
  border-radius: 10px;
}

.tree-children {
  display: none;
  padding: 0 0 4px 0;
}
.tree-children.open { display: block; }

.tree-leaf {
  display: block;
  padding: 6px 20px 6px 36px;
  font-size: 0.85rem;
  color: var(--text-dim);
  cursor: pointer;
  background: none;
  border: none;
  width: 100%;
  text-align: left;
  font-family: inherit;
  position: relative;
}
.tree-leaf::before {
  content: "›";
  position: absolute;
  left: 24px;
  color: var(--border);
}
.tree-leaf:hover { color: var(--teal); background: var(--bg-card); }
.tree-leaf.active {
  color: var(--teal);
  background: var(--bg-card);
  border-right: 2px solid var(--teal);
}
.tree-leaf.active::before { color: var(--teal); }
.tree-leaf.locked { opacity: 0.4; cursor: not-allowed; }

/* 3rd-level sub-group (e.g. Spring AI + Llama inside AI) */
.tree-subcat { margin: 4px 0; }

.tree-subcat-btn {
  width: 100%;
  background: none;
  border: none;
  color: var(--text-dim);
  font-family: inherit;
  font-size: 0.82rem;
  padding: 6px 20px 6px 28px;
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
}
.tree-subcat-btn:hover { color: var(--teal); }
.tree-subcat-btn .caret { font-size: 0.6rem; color: var(--text-dim); transition: transform 0.2s; flex-shrink: 0; }
.tree-subcat-btn.open .caret { transform: rotate(90deg); }

.tree-subchildren { display: none; }
.tree-subchildren.open { display: block; }

/* Sub-level leaves are indented one step further */
.tree-leaf--sub { padding-left: 48px; font-size: 0.82rem; }
.tree-leaf--sub::before { left: 36px; }

/* Quiz main area */
.quiz-main {
  padding: 40px 48px;
  max-width: 800px;
}

.quiz-header {
  margin-bottom: 32px;
}
.quiz-header .breadcrumb {
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.quiz-header .breadcrumb span { color: var(--teal); }

.copy-link-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-dim);
  font-family: inherit;
  font-size: 0.72rem;
  padding: 2px 10px;
  border-radius: 20px;
  cursor: pointer;
  margin-left: auto;
  transition: border-color 0.15s, color 0.15s;
}
.copy-link-btn:hover { border-color: var(--teal); color: var(--teal); }
.quiz-header h2 {
  color: var(--orange);
  margin: 0 0 6px;
  font-size: 1.4rem;
}
.quiz-header p {
  color: var(--text-dim);
  font-size: 0.9rem;
  margin: 0;
}

/* Welcome screen */
.quiz-welcome {
  text-align: center;
  padding: 80px 40px;
}
.quiz-welcome h2 { color: var(--teal); font-size: 1.6rem; }
.quiz-welcome p { color: var(--text-dim); max-width: 500px; margin: 0 auto 24px; }

/* Question card */
.question-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 24px;
  margin-bottom: 20px;
}
.question-num {
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-bottom: 10px;
}

/* Difficulty badge */
.diff-badge {
  display: inline-block;
  font-size: 0.6rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 10px;
  margin-left: 6px;
  vertical-align: middle;
  border: 1px solid transparent;
}
.diff-easy   { background: rgba(76, 233, 196, 0.12); color: #4ce9c4; border-color: rgba(76, 233, 196, 0.35); }
.diff-medium { background: rgba(245, 180, 60, 0.12);  color: #f5b43c; border-color: rgba(245, 180, 60, 0.35); }
.diff-hard   { background: rgba(240, 90, 90, 0.14);   color: #ff7676; border-color: rgba(240, 90, 90, 0.4); }
.question-text {
  color: var(--text);
  font-size: 1rem;
  margin: 0 0 18px;
  line-height: 1.5;
}
.question-text code {
  background: #060a16;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
  color: var(--orange);
}

.options { display: flex; flex-direction: column; gap: 10px; }
.option-label {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  color: var(--text);
  transition: border-color 0.15s, background 0.15s;
  line-height: 1.4;
}
.option-label:hover { border-color: var(--teal); background: rgba(76,233,196,0.05); }
.option-label input[type=radio] { display: none; }
.option-label .opt-key {
  flex-shrink: 0;
  width: 22px;
  height: 22px;
  border: 1px solid var(--border);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: var(--text-dim);
  margin-top: 1px;
}

.option-label.selected { border-color: var(--orange); background: rgba(245,166,35,0.07); }
.option-label.selected .opt-key { border-color: var(--orange); color: var(--orange); }
.option-label.correct { border-color: var(--teal) !important; background: rgba(76,233,196,0.12) !important; }
.option-label.correct .opt-key { border-color: var(--teal); color: var(--teal); }
.option-label.wrong { border-color: #e05252 !important; background: rgba(224,82,82,0.1) !important; }
.option-label.wrong .opt-key { border-color: #e05252; color: #e05252; }

.explanation {
  margin-top: 14px;
  padding: 12px 14px;
  background: rgba(76,233,196,0.06);
  border-left: 3px solid var(--teal);
  border-radius: 0 6px 6px 0;
  font-size: 0.85rem;
  color: var(--text-dim);
  display: none;
}
.explanation.show { display: block; }
.explanation code {
  background: #060a16;
  padding: 1px 5px;
  border-radius: 3px;
  font-size: 0.88em;
  color: var(--orange);
}

/* Controls */
.quiz-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 28px;
}
.btn {
  background: var(--teal);
  color: var(--bg);
  border: none;
  padding: 10px 24px;
  border-radius: 6px;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
}
.btn:hover { opacity: 0.88; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn.secondary {
  background: var(--bg-card);
  color: var(--teal);
  border: 1px solid var(--teal);
}
.progress-text { font-size: 0.85rem; color: var(--text-dim); }
.progress-bar-wrap {
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  margin-bottom: 28px;
}
.progress-bar-fill {
  height: 100%;
  background: linear-gradient(to right, var(--orange), var(--teal));
  border-radius: 2px;
  transition: width 0.3s;
}

/* Score screen */
.score-screen {
  text-align: center;
  padding: 40px 0;
}
.score-circle {
  width: 120px;
  height: 120px;
  border: 4px solid var(--teal);
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: 0 auto 24px;
}
.score-circle .score-num { font-size: 2rem; color: var(--orange); font-weight: 700; }
.score-circle .score-denom { font-size: 0.8rem; color: var(--text-dim); }
.score-msg { font-size: 1rem; color: var(--teal); margin-bottom: 8px; }
.score-sub { font-size: 0.85rem; color: var(--text-dim); margin-bottom: 28px; }
.score-actions { display: flex; gap: 12px; justify-content: center; }

@media (max-width: 680px) {
  .quiz-layout { grid-template-columns: 1fr; }
  .quiz-sidebar { position: static; height: auto; border-right: none; border-bottom: 1px solid var(--border); }
  .quiz-main { padding: 24px 20px; }
}