/* ═══════════════════════════════════════════════════════
   Density & Pressure — Clay Design System Extensions
   Only page-specific overrides. Everything else comes from
   clay-system.css + content.css.
   ═══════════════════════════════════════════════════════ */

/* ── Sidebar Toggle Button ── */
.sidebar-toggle {
  display: none;
  position: fixed;
  top: 72px;
  left: 12px;
  z-index: 200;
  align-items: center;
  gap: 6px;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(160,150,180,0.15);
  border-radius: 20px;
  padding: 8px 14px;
  font-family: var(--font-heading);
  font-size: 13px;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--dur-fast) var(--ease-smooth);
  box-shadow: var(--shadow-card);
}
.sidebar-toggle:hover {
  background: rgba(255,255,255,1);
  border-color: var(--accent);
  color: var(--accent);
}
.sidebar-toggle i {
  font-size: 14px;
}

/* ── Content Sidebar ── */
.content-sidebar {
  position: fixed;
  top: 64px;
  left: 0;
  bottom: 0;
  z-index: 150;
  width: 220px;
  background: rgba(255,255,255,0.80);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-right: 1px solid rgba(160,150,180,0.12);
  overflow-y: auto;
  padding: 20px 0;
  transition: transform 0.35s var(--ease-smooth);
  display: flex;
  flex-direction: column;
  scrollbar-width: thin;
  scrollbar-color: rgba(160,150,180,0.2) transparent;
}
.content-sidebar::-webkit-scrollbar { width: 4px; }
.content-sidebar::-webkit-scrollbar-thumb { background: rgba(160,150,180,0.2); border-radius: 4px; }

.content-sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 20px 16px;
  border-bottom: 1px solid rgba(160,150,180,0.08);
  margin-bottom: 12px;
}
.content-sidebar-brand {
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 15px;
  background: linear-gradient(135deg, var(--accent), var(--accent-alt));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
}
.sidebar-close {
  display: none;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 18px;
  cursor: pointer;
  padding: 4px;
  border-radius: 8px;
  transition: all var(--dur-fast);
}
.sidebar-close:hover {
  background: rgba(160,150,180,0.1);
  color: var(--text-primary);
}

.content-sidebar-links {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 0 12px;
}
.content-sidebar-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  text-decoration: none;
  transition: all var(--dur-fast) var(--ease-smooth);
  font-family: var(--font-heading);
}
.content-sidebar-link:hover {
  background: rgba(124,58,237,0.06);
  color: var(--text-primary);
}
.content-sidebar-link.active {
  background: rgba(124,58,237,0.1);
  color: var(--accent);
}
.sidebar-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 8px;
  background: rgba(160,150,180,0.1);
  font-size: 11px;
  font-weight: 800;
  color: var(--text-muted);
  flex-shrink: 0;
  transition: all var(--dur-fast);
}
.content-sidebar-link.active .sidebar-num {
  background: rgba(124,58,237,0.15);
  color: var(--accent);
}
.sidebar-label {
  line-height: 1.2;
}

/* ── Content Main ── */
.content-main {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  transition: all 0.35s var(--ease-smooth);
}

/* ── Page heading ── */
.content-main > h1 {
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: clamp(2rem, 4vw, 3rem);
  text-align: center;
  color: var(--text-primary);
  margin-bottom: 32px;
  line-height: 1.1;
  letter-spacing: -0.02em;
  padding-top: 80px;
}

/* ── Section heading with icon ── */
h2 .icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 12px;
  font-size: 1.2rem;
  flex-shrink: 0;
  margin-right: 10px;
  vertical-align: middle;
}
.icon-blue  { background: linear-gradient(135deg, #BFDBFE, #3B82F6); }
.icon-red   { background: linear-gradient(135deg, #FECACA, #EF4444); }
.icon-green { background: linear-gradient(135deg, #A7F3D0, #10B981); }
.icon-purple { background: linear-gradient(135deg, #DDD6FE, #8B5CF6); }

/* ── Learning Outcomes ── */
.learning-outcomes {
  background: rgba(124,58,237,0.04);
  border-left: 4px solid var(--accent);
  border-radius: 16px;
  padding: 16px 20px;
  margin-bottom: 20px;
}
.learning-outcomes h4 {
  font-family: var(--font-heading);
  font-size: 14px;
  color: var(--accent);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.learning-outcomes ul {
  list-style: none;
  padding: 0;
}
.learning-outcomes li {
  font-size: 14px;
  color: var(--text-muted);
  padding: 4px 0;
  padding-left: 20px;
  position: relative;
}
.learning-outcomes li::before {
  content: "\2713";
  position: absolute;
  left: 0;
  color: var(--accent-emerald);
  font-weight: 700;
}

/* ── Formula Box ── */
.formula-box {
  background: linear-gradient(135deg, rgba(124,58,237,0.05), rgba(219,39,119,0.04));
  border-radius: 20px;
  padding: 20px 24px;
  margin: 16px 0;
  text-align: center;
}
.formula-box p {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  font-family: var(--font-heading);
}

/* ── Example / Info boxes ── */
.example-box {
  background: rgba(245,158,11,0.04);
  border-left: 4px solid var(--accent-amber);
  border-radius: 16px;
  padding: 14px 18px;
  margin: 14px 0;
  font-size: 14px;
  color: var(--text-muted);
}
.example-box strong { color: var(--text-primary); }
.example-box ul { padding-left: 1.25rem; margin-top: 0.25rem; }
.example-box ul li { margin-bottom: 4px; }

.info-box {
  background: rgba(14,165,233,0.04);
  border-left: 4px solid var(--accent-blue);
  border-radius: 16px;
  padding: 16px 20px;
  margin: 16px 0;
}
.info-box h3 { font-size: 1.1rem; margin-bottom: 12px; }
.info-box h4 {
  font-family: var(--font-heading);
  font-size: 14px;
  font-weight: 700;
  color: var(--accent-blue);
  margin: 14px 0 8px;
}
.info-box strong { color: var(--text-primary); }

.warning-box {
  background: rgba(245,158,11,0.06);
  border-left: 4px solid var(--accent-amber);
  border-radius: 16px;
  padding: 14px 18px;
  margin: 14px 0;
  font-size: 13px;
  color: var(--text-muted);
}
.warning-box strong { color: var(--text-primary); }

.materials-box {
  background: rgba(255,255,255,0.5);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(160,150,180,0.1);
  border-radius: 20px;
  padding: 16px 20px;
  margin: 12px 0;
}
.materials-box strong { font-family: var(--font-heading); color: var(--text-primary); }
.materials-box ul { padding-left: 1.25rem; margin-top: 6px; }
.materials-box li { font-size: 14px; color: var(--text-muted); margin-bottom: 3px; }

/* ── Steps (Practical Investigation) ── */
.step {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin: 8px 0;
  font-size: 14px;
  color: var(--text-muted);
}
.step-num {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent-light), var(--accent));
  color: #fff;
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 13px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ── Explanation paragraph ── */
.explanation {
  background: rgba(14,165,233,0.04);
  border-left: 4px solid var(--accent-blue);
  border-radius: 16px;
  padding: 14px 18px;
  margin: 14px 0;
  font-size: 14px;
  color: var(--text-muted);
}
.explanation strong { color: var(--text-primary); }

/* ── Density Reference Table ── */
.density-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  border-radius: 20px;
  overflow: hidden;
  margin: 16px 0;
  font-size: 14px;
  box-shadow: var(--shadow-card);
}
.density-table thead tr { background: linear-gradient(135deg, rgba(124,58,237,0.08), rgba(219,39,119,0.04)); }
.density-table th {
  color: var(--accent);
  font-weight: 700;
  padding: 12px 16px;
  text-align: left;
  font-family: var(--font-heading);
  font-size: 13px;
}
.density-table td {
  padding: 10px 16px;
  background: rgba(255,255,255,0.7);
  border-bottom: 1px solid rgba(160,150,180,0.08);
  color: var(--text-muted);
}
.density-table tr:last-child td { border-bottom: none; }
.density-table tr:hover td { background: rgba(255,255,255,0.9); }
.swatch {
  display: inline-block;
  width: 14px;
  height: 14px;
  border-radius: 6px;
  margin-right: 8px;
  vertical-align: middle;
  box-shadow: inset 0 1px 2px rgba(0,0,0,0.15);
}

/* ── Diagram wrap ── */
.diagram-wrap {
  background: rgba(255,255,255,0.5);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: 20px;
  padding: 16px;
  margin: 16px 0;
  border: 1px solid rgba(160,150,180,0.1);
  text-align: center;
}
.diagram-wrap svg {
  max-width: 100%;
  height: auto;
  border-radius: 12px;
}

/* ── Material buttons (unique to density page) ── */
#material-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}
.material-btn {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 10px 16px;
  border-radius: var(--radius-btn);
  border: none;
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--dur-fast);
  font-family: var(--font-heading);
  min-width: 72px;
  box-shadow: var(--shadow-btn);
}
.material-btn span {
  font-size: 10px;
  font-weight: 400;
  opacity: 0.85;
  font-family: var(--font-body);
}
.material-btn:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-btn-hover);
}
.material-btn:active {
  transform: scale(0.92);
  box-shadow: var(--shadow-pressed);
}

/* ── Simulation containers ── */
.sim-container {
  background: linear-gradient(135deg, rgba(16,185,129,0.04), rgba(14,165,233,0.03));
  border: 1px solid rgba(160,150,180,0.1);
  border-radius: 24px;
  padding: 24px;
  margin: 20px 0 16px;
  transition: all var(--dur-med) var(--ease-smooth);
}
.sim-container:hover { border-color: rgba(124,58,237,0.25); }
.sim-container h3 {
  font-family: var(--font-heading);
  font-size: 1.05rem;
  margin-bottom: 8px;
}
.sim-container > p {
  font-size: 0.88rem;
  margin-bottom: 12px;
}
.sim-canvas-wrap {
  margin-top: 12px;
}
.sim-canvas-wrap canvas {
  display: block;
  width: 100%;
  max-width: 700px;
  height: auto;
  margin: 0 auto;
  border-radius: 16px;
  background: #f8f7fc;
  border: 1px solid rgba(160,150,180,0.08);
}
.sim-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  background: rgba(255,255,255,0.4);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(160,150,180,0.1);
  border-radius: 20px;
  padding: 16px;
  margin-bottom: 12px;
}

/* ── Slider groups ── */
.slider-group {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
  min-width: 180px;
}
.slider-group label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-heading);
  white-space: nowrap;
}
.slider-group input[type="range"] {
  flex: 1;
  max-width: 180px;
  accent-color: var(--accent);
}
.slider-group select {
  padding: 8px 12px;
  border: 2px solid rgba(160,150,180,0.15);
  border-radius: 14px;
  font-family: var(--font-body);
  font-size: 13px;
  background: #EFEBF5;
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--dur-fast);
}
.slider-group select:focus {
  outline: none;
  background: #fff;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(124,58,237,0.12);
}
.slider-value {
  font-family: var(--font-heading);
  font-size: 14px;
  font-weight: 700;
  color: var(--accent);
  background: rgba(124,58,237,0.06);
  padding: 4px 12px;
  border-radius: 12px;
  white-space: nowrap;
}

/* ── Readout displays (Depth & Hydraulic) ── */
.readout {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin: 12px 0;
}
.readout-item {
  background: rgba(255,255,255,0.5);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(160,150,180,0.1);
  border-radius: 16px;
  padding: 10px 18px;
  text-align: center;
  flex: 1;
  min-width: 120px;
  box-shadow: var(--shadow-card);
}
.readout-item .label {
  font-size: 11px;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-family: var(--font-heading);
}
.readout-item .value {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--accent);
  font-family: var(--font-heading);
  margin-top: 2px;
}
.readout-item .unit {
  font-size: 11px;
  color: var(--text-muted);
  font-weight: 500;
}

/* ── Calculator grids ── */
.calc-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 12px 0;
}
.calc-field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.calc-field label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-heading);
}
.calc-field input[type="number"] {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid rgba(160,150,180,0.15);
  border-radius: 16px;
  font-size: 14px;
  background: #EFEBF5;
  color: var(--text-primary);
  font-family: var(--font-body);
  transition: all var(--dur-fast);
  box-sizing: border-box;
}
.calc-field input[type="number"]:focus {
  outline: none;
  background: #fff;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(124,58,237,0.12);
}
.calc-field select {
  padding: 10px 14px;
  border: 2px solid rgba(160,150,180,0.15);
  border-radius: 14px;
  font-family: var(--font-body);
  font-size: 13px;
  background: #EFEBF5;
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--dur-fast);
}
.calc-field select:focus {
  outline: none;
  background: #fff;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(124,58,237,0.12);
}

/* ── Calculator result ── */
.calc-result {
  background: rgba(16,185,129,0.06);
  border: 1px solid rgba(16,185,129,0.2);
  border-radius: 20px;
  padding: 16px 20px;
  margin-top: 16px;
  text-align: center;
  font-weight: 700;
  color: var(--accent-emerald);
  line-height: 1.7;
  display: none;
}
.calc-result strong { color: inherit; }
.calc-result.show { display: block; }

/* ── Buttons inside sims and calculators ── */
.sim-container .btn-primary,
.sim-container .btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: none;
  border-radius: var(--radius-btn);
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 700;
  padding: 12px 24px;
  cursor: pointer;
  transition: all var(--dur-fast);
  text-decoration: none;
  line-height: 1;
  min-height: 44px;
  margin-top: 8px;
}
.sim-container .btn-primary {
  background: linear-gradient(135deg, var(--accent-light), var(--accent));
  color: #fff;
  box-shadow: var(--shadow-btn);
}
.sim-container .btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-btn-hover); }
.sim-container .btn-primary:active { transform: scale(0.95); box-shadow: var(--shadow-pressed); }
.sim-container .btn-secondary {
  background: #fff;
  color: var(--text-primary);
  box-shadow: var(--shadow-btn);
}
.sim-container .btn-secondary:hover { transform: translateY(-2px); box-shadow: var(--shadow-btn-hover); }
.sim-container .btn-secondary:active { transform: scale(0.95); box-shadow: var(--shadow-pressed); }

/* ── Quiz ── */
.quiz-progress {
  font-family: var(--font-heading);
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 16px;
  text-align: center;
}
.quiz-question {
  background: rgba(255,255,255,0.5);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(160,150,180,0.1);
  border-radius: 20px;
  padding: 20px;
  margin-bottom: 16px;
  transition: all var(--dur-med) var(--ease-smooth);
}
.quiz-question:hover { background: rgba(255,255,255,0.7); }
.quiz-question h4 {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
}
.quiz-options { margin: 8px 0; }
.quiz-option {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  margin: 4px 0;
  border-radius: 14px;
  cursor: pointer;
  transition: background var(--dur-fast);
  font-size: 14px;
  color: var(--text-muted);
}
.quiz-option:hover { background: rgba(124,58,237,0.05); }
.quiz-option input[type="radio"] {
  accent-color: var(--accent);
  width: 18px;
  height: 18px;
  cursor: pointer;
  flex-shrink: 0;
}
.quiz-feedback {
  margin-top: 8px;
  padding: 8px 14px;
  border-radius: 12px;
  font-size: 13px;
  font-weight: 600;
  display: none;
}
.quiz-feedback.show { display: block; }
.quiz-feedback.correct { background: rgba(16,185,129,0.1); color: var(--accent-emerald); }
.quiz-feedback.incorrect { background: rgba(244,63,94,0.1); color: var(--accent-rose); }
.quiz-score {
  text-align: center;
  padding: 24px;
  border-radius: 24px;
  margin-top: 20px;
  background: linear-gradient(135deg, var(--accent-light), var(--accent));
  color: #fff;
  display: none;
}
.quiz-score.show { display: block; }
.quiz-score h4 {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 800;
  margin-bottom: 12px;
}
.quiz-score p { color: rgba(255,255,255,0.9); font-size: 14px; margin-bottom: 4px; }
.quiz-score .score-num {
  font-size: 2.5rem;
  font-weight: 900;
  font-family: var(--font-heading);
  display: block;
  margin-bottom: 4px;
}

/* ── Quiz box (wrapper) ── */
.quiz-box {
  margin: 16px 0;
}

/* ── Canvas sizing hints ── */
canvas#tankCanvas,
canvas#paCanvas,
canvas#depthCanvas,
canvas#hydCanvas {
  max-width: 100%;
}

/* ── Card default (visible by default, no scroll-reveal) ── */
.card { opacity: 1; transform: none; }

/* ── Mobile ── */
@media (max-width: 768px) {
  .sidebar-toggle { display: flex; }
  .content-sidebar {
    transform: translateX(-100%);
    width: 260px;
  }
  .content-sidebar.open {
    transform: translateX(0);
  }
  .sidebar-close { display: block; }
  .content-main {
    padding: 0 16px;
    margin-left: 0;
  }
  .material-btn { min-width: 60px; font-size: 11px; padding: 8px 12px; }
  .sim-container { padding: 16px; }
  .sim-controls { flex-direction: column; align-items: stretch; padding: 12px; }
  .slider-group { min-width: auto; }
  .slider-group input[type="range"] { max-width: 100%; }
  .readout { flex-direction: column; }
  .readout-item { min-width: auto; }
  .calc-grid { grid-template-columns: 1fr; }
  .card { padding: 24px; }
  .density-table { font-size: 13px; }
  .density-table th,
  .density-table td { padding: 8px 12px; }
  .quiz-question { padding: 16px; }
}