/* Sidebar navigation */
.nav-home-link, .nav-favorites-link {
  display: flex; align-items: center; gap: 10px; padding: 9px 10px; border-radius: var(--radius-sm);
  color: var(--text-secondary); font-size: 14px; margin-bottom: 4px; font-weight: 500;
}
.nav-home-link:hover, .nav-favorites-link:hover, .nav-home-link.active, .nav-favorites-link.active {
  background: var(--surface-hover); color: var(--text-primary);
}
.nav-favorites-link { margin-top: 14px; border-top: 1px solid var(--border); padding-top: 16px; }
.nav-section-label {
  font-size: 11px; text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-tertiary);
  margin: 16px 10px 6px;
}
.nav-category-header {
  width: 100%; display: flex; align-items: center; gap: 10px; background: none; border: none;
  color: var(--text-primary); padding: 8px 10px; border-radius: var(--radius-sm); font-size: 14px; font-weight: 500;
}
.nav-category-header:hover { background: var(--surface-hover); }
.nav-icon { display: inline-flex; width: 18px; justify-content: center; color: var(--accent); }
.nav-caret { margin-left: auto; font-size: 10px; color: var(--text-tertiary); transition: transform 0.15s; }
.nav-category.open .nav-caret { transform: rotate(180deg); }
.nav-category-list { display: none; flex-direction: column; padding-left: 30px; margin-top: 2px; }
.nav-category.open .nav-category-list { display: flex; }
.nav-demo-link { padding: 6px 10px; border-radius: var(--radius-sm); color: var(--text-secondary); font-size: 13.5px; }
.nav-demo-link:hover { background: var(--surface-hover); color: var(--text-primary); }
.nav-demo-link.active { background: var(--accent-soft); color: var(--accent); font-weight: 500; }
.nav-empty { padding: 6px 10px; font-size: 12px; color: var(--text-tertiary); font-style: italic; }

/* Search */
.search-result {
  display: flex; justify-content: space-between; align-items: center; padding: 10px 14px;
  border-bottom: 1px solid var(--border); font-size: 14px;
}
.search-result:last-child { border-bottom: none; }
.search-result:hover { background: var(--surface-hover); }
.search-result-cat { color: var(--text-tertiary); font-size: 12px; }
.search-empty { padding: 14px; color: var(--text-secondary); font-size: 13px; }

/* Hero / home */
.hero { padding: 44px 0 16px; max-width: 760px; }
.hero h1 { font-size: 34px; margin-bottom: 10px; color: var(--text-primary); }
.hero p { font-size: 16.5px; color: var(--text-secondary); }

.section-heading { font-size: 18px; margin: 34px 0 16px; }

.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(270px, 1fr)); gap: 18px; }

.demo-card {
  display: flex; flex-direction: column; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius-lg); overflow: hidden; transition: transform 0.15s ease, border-color 0.15s ease, background 0.15s ease;
}
.demo-card:hover { border-color: var(--accent); transform: translateY(-2px); background: var(--surface-hover); }
.demo-card-preview {
  height: 140px; background: var(--surface-alt); position: relative; display: flex; align-items: center;
  justify-content: center; overflow: hidden;
}
.demo-card-preview.preview-fallback {
  font-size: 38px; color: var(--text-tertiary);
  background: linear-gradient(135deg, var(--surface-alt), var(--surface));
}
.demo-card-preview canvas { width: 100%; height: 100%; display: block; }
.demo-card-body { padding: 14px 16px 16px; display: flex; flex-direction: column; gap: 6px; }
.demo-card-title-row { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.demo-card-title-row h3 { font-size: 15px; margin: 0; }
.demo-card-desc { font-size: 13px; margin: 0; }
.demo-card-meta { font-size: 12px; color: var(--text-tertiary); }

.fav-toggle { background: none; border: none; color: var(--text-tertiary); font-size: 17px; padding: 2px; line-height: 1; flex-shrink: 0; }
.fav-toggle:hover { color: var(--accent); }
.fav-toggle.active { color: var(--color-energy); }
.fav-toggle.lg { font-size: 23px; }

.category-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px,1fr)); gap: 14px; }
.category-tile {
  display: flex; flex-direction: column; gap: 6px; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 18px;
}
.category-tile:hover { border-color: var(--accent); background: var(--surface-hover); }
.category-symbol { font-size: 24px; color: var(--accent); }
.category-name { font-weight: 600; font-size: 14px; }
.category-count { font-size: 12px; color: var(--text-tertiary); }

.category-page-header { display: flex; gap: 16px; align-items: flex-start; margin-bottom: 12px; }
.category-symbol-lg { font-size: 36px; color: var(--accent); line-height: 1; }
.category-page-header h1 { font-size: 24px; }
.category-page-header p { margin: 0; }

.page-title { margin-bottom: 20px; }

.empty-state { padding: 70px 20px; text-align: center; color: var(--text-secondary); }
.empty-title { font-size: 16px; color: var(--text-primary); margin-bottom: 6px; }
.empty-sub { font-size: 14px; margin-bottom: 18px; }

/* Controls panel */
.panel-section-title {
  font-size: 11px; text-transform: uppercase; letter-spacing: 0.07em; color: var(--text-tertiary);
  margin: 18px 0 10px; font-weight: 600;
}
.panel-section-title:first-child { margin-top: 0; }
.control-group { margin-bottom: 16px; }
.control-row { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 6px; gap: 8px; }
.control-label { font-size: 13px; color: var(--text-secondary); }
.control-value { font-family: var(--font-mono); font-size: 12.5px; color: var(--text-primary); white-space: nowrap; }
.control-hint { font-size: 12px; color: var(--text-tertiary); margin: -8px 0 14px; }

input[type=range].slider {
  -webkit-appearance: none; appearance: none; width: 100%; height: 4px; border-radius: 2px;
  background: var(--border); outline: none; display: block;
}
input[type=range].slider::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none; width: 15px; height: 15px; border-radius: 50%;
  background: var(--accent); cursor: pointer; border: 2px solid var(--bg); box-shadow: 0 0 0 1px var(--accent);
}
input[type=range].slider::-moz-range-thumb {
  width: 15px; height: 15px; border-radius: 50%; background: var(--accent); cursor: pointer; border: 2px solid var(--bg);
}

.select-input {
  width: 100%; background: var(--surface-alt); border: 1px solid var(--border); color: var(--text-primary);
  padding: 8px 10px; border-radius: var(--radius-sm); font-size: 13px; margin-top: 4px;
}

.checkbox-row { display: flex; align-items: center; gap: 8px; margin-bottom: 10px; }
.checkbox-row input[type=checkbox] { width: 15px; height: 15px; accent-color: var(--accent); }
.checkbox-label { font-size: 13px; color: var(--text-secondary); }

.button-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 4px; }
.lab-btn {
  border-radius: var(--radius-sm); padding: 9px 14px; font-size: 13.5px; font-weight: 500;
  border: 1px solid var(--border); background: var(--surface-alt); color: var(--text-primary);
  transition: background 0.15s, border-color 0.15s;
}
.lab-btn:hover { background: var(--surface-hover); }
.lab-btn-primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.lab-btn-primary:hover { background: var(--accent-strong); }
.lab-btn:disabled { opacity: 0.45; cursor: not-allowed; }

.formula-box {
  font-family: var(--font-mono); font-size: 16px; text-align: center; background: var(--surface-alt);
  border: 1px solid var(--border); border-radius: var(--radius-md); padding: 14px; margin: 10px 0; color: var(--accent);
  letter-spacing: 0.02em;
}

/* Stats */
.stat-row { display: flex; flex-direction: column; gap: 3px; }
.stat-label { font-size: 11px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-tertiary); }
.stat-value { font-family: var(--font-mono); font-size: 15px; color: var(--text-primary); }

/* Chart */
.chart-wrapper { width: 100%; height: 160px; }
.chart-wrapper canvas { width: 100%; height: 100%; display: block; }
.chart-title {
  font-size: 11px; text-transform: uppercase; letter-spacing: 0.06em; color: var(--text-tertiary);
  margin: 6px 0 6px; grid-column: 1 / -1;
}

.demo-error {
  display: flex; align-items: center; justify-content: center; width: 100%; height: 100%;
  color: var(--color-danger); font-size: 14px; padding: 20px; text-align: center;
}

/* Explanation */
.demo-explanation h2 { font-size: 18px; }
.how-it-works-body p { font-size: 14px; }
.how-it-works-body ul { padding-left: 18px; font-size: 14px; color: var(--text-secondary); }
.how-it-works-body strong { color: var(--text-primary); }

/* Sorting visualization */
.sort-canvas-wrap { width: 100%; height: 100%; display: flex; flex-direction: column; padding: 14px; }
.sort-canvas-wrap canvas { flex: 1; width: 100%; height: auto; }
.sort-legend { display: flex; gap: 16px; font-size: 11px; color: var(--text-tertiary); padding-top: 10px; flex-wrap: wrap; }
.sort-legend span { display: flex; align-items: center; gap: 5px; }
.sort-legend i { width: 9px; height: 9px; border-radius: 2px; display: inline-block; }

/* Generic full-size sim canvas wrap */
.sim-fill { width: 100%; height: 100%; position: relative; }
.sim-fill canvas { width: 100%; height: 100%; display: block; }
.sim-hint {
  position: absolute; bottom: 10px; left: 12px; font-size: 12px; color: var(--text-tertiary);
  background: rgba(11,13,16,0.6); padding: 4px 8px; border-radius: var(--radius-sm); pointer-events: none;
}
.sim-progress-wrap { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; flex-direction: column; gap: 12px; background: rgba(11,13,16,0.55); }
.sim-progress-bar { width: 220px; height: 8px; background: var(--border); border-radius: 4px; overflow: hidden; }
.sim-progress-fill { height: 100%; background: var(--accent); width: 0%; transition: width 0.1s linear; }
.sim-progress-label { font-size: 13px; color: var(--text-secondary); font-family: var(--font-mono); }

@media (max-width: 980px) {
  .demo-controls-panel { padding: 0; border: none; background: none; }
  .controls-toggle {
    display: block; width: 100%; text-align: left; background: var(--surface); border: 1px solid var(--border);
    border-radius: var(--radius-lg); padding: 12px 16px; color: var(--text-primary); font-size: 14px; margin-bottom: 10px;
  }
  .demo-controls-body { display: none; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 16px; }
  .demo-controls-panel.expanded .demo-controls-body { display: block; }
}