:root {
  --bg-dark: #0c0d12;
  --bg-card: rgba(22, 24, 34, 0.75);
  --bg-card-border: rgba(255, 255, 255, 0.08);
  --bg-elevated: #161822;
  --accent-pink: #f43f5e;
  --accent-pink-glow: rgba(244, 63, 94, 0.35);
  --accent-rose: #fda4af;
  --accent-purple: #a855f7;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --font-sans: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --shadow-card: 0 16px 36px -8px rgba(0, 0, 0, 0.45);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-main);
  min-height: 100vh;
  line-height: 1.5;
  overflow-x: hidden;
  position: relative;
}

/* Background Atmosphere Glow */
.background-glow {
  position: fixed;
  top: -20vh;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 600px;
  background: radial-gradient(circle, rgba(244, 63, 94, 0.12) 0%, rgba(168, 85, 247, 0.08) 45%, transparent 70%);
  filter: blur(80px);
  pointer-events: none;
  z-index: 0;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 32px;
  backdrop-filter: blur(16px);
  background: rgba(12, 13, 18, 0.75);
  border-bottom: 1px solid var(--bg-card-border);
}

.logo-group {
  display: flex;
  align-items: center;
  gap: 12px;
}

.domain-tag {
  font-size: 1.4rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  background: linear-gradient(135deg, #fff 30%, var(--accent-rose) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.badge {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  background: rgba(244, 63, 94, 0.15);
  color: var(--accent-pink);
  border: 1px solid rgba(244, 63, 94, 0.3);
  padding: 2px 8px;
  border-radius: 999px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-size: 0.88rem;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  text-decoration: none;
  user-select: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-pink), #e11d48);
  color: #fff;
  box-shadow: 0 4px 18px var(--accent-pink-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(244, 63, 94, 0.5);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: var(--bg-elevated);
  color: var(--text-main);
  border: 1px solid var(--bg-card-border);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.16);
  transform: translateY(-1px);
}

.btn-icon {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
  border: 1px solid var(--bg-card-border);
  padding: 8px 14px;
}

.btn-icon:hover {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.1);
}

/* Main Container */
.main-container {
  position: relative;
  z-index: 1;
  max-width: 1000px;
  margin: 0 auto;
  padding: 28px 20px 80px;
  display: flex;
  flex-direction: column;
  gap: 60px;
}

/* Simulator Section */
.simulator-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.section-heading {
  text-align: center;
}

.main-title {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  margin-bottom: 6px;
  background: linear-gradient(180deg, #ffffff 40%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  color: var(--text-muted);
  font-size: 1rem;
}

/* Canvas Card */
.canvas-card {
  position: relative;
  width: 100%;
  max-width: 820px;
  height: 480px;
  background: radial-gradient(120% 100% at 50% 0%, #171926 0%, #0d0e15 100%);
  border: 1px solid var(--bg-card-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card), inset 0 1px 0 rgba(255, 255, 255, 0.06);
  overflow: hidden;
  touch-action: none;
}

#physicsCanvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: grab;
}

#physicsCanvas:active {
  cursor: grabbing;
}

.canvas-overlay-hints {
  position: absolute;
  top: 14px;
  left: 50%;
  transform: translateX(-50%);
  pointer-events: none;
  z-index: 5;
  transition: opacity 0.5s ease;
}

.hint-pill {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  background: rgba(12, 13, 18, 0.75);
  backdrop-filter: blur(8px);
  border: 1px solid var(--bg-card-border);
  padding: 6px 14px;
  border-radius: 999px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

/* Control Panel */
.glass-card {
  width: 100%;
  max-width: 820px;
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--bg-card-border);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-card);
}

.control-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.control-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.sliders-row {
  grid-template-columns: 1fr 1fr 1fr;
  align-items: flex-end;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.control-label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.label-icon {
  font-size: 1rem;
}

/* Segmented Control */
.segmented-control {
  display: flex;
  background: rgba(0, 0, 0, 0.35);
  padding: 4px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.04);
}

.segment-btn {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 8px 10px;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.segment-btn:hover {
  color: var(--text-main);
}

.segment-btn.active {
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.35);
}

/* Custom Range Slider */
.slider-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.slider-value {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--accent-rose);
  font-weight: 600;
}

.custom-range {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 4px;
  outline: none;
  margin: 10px 0 4px;
}

.custom-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-pink);
  box-shadow: 0 0 10px var(--accent-pink-glow);
  cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease;
}

.custom-range::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

.custom-range::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border: none;
  border-radius: 50%;
  background: var(--accent-pink);
  box-shadow: 0 0 10px var(--accent-pink-glow);
  cursor: pointer;
}

/* Palette Picker */
.palette-picker {
  display: flex;
  gap: 10px;
  align-items: center;
  padding: 4px 0;
}

.palette-swatch {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--swatch-1), var(--swatch-2));
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, border-color 0.2s ease;
  padding: 0;
}

.palette-swatch:hover {
  transform: scale(1.15);
}

.palette-swatch.active {
  border-color: #fff;
  transform: scale(1.18);
  box-shadow: 0 0 12px rgba(255, 255, 255, 0.4);
}

/* Facts Section */
.facts-section {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.section-title {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  text-align: center;
}

.section-sub {
  color: var(--text-muted);
  text-align: center;
  margin-top: -16px;
}

.facts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.fact-card {
  background: var(--bg-card);
  border: 1px solid var(--bg-card-border);
  border-radius: var(--radius-md);
  padding: 22px;
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.fact-card:hover {
  transform: translateY(-3px);
  border-color: rgba(255, 255, 255, 0.16);
}

.fact-icon {
  font-size: 1.6rem;
  margin-bottom: 10px;
}

.fact-title {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 6px;
  color: #fff;
}

.fact-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Slang Section */
.slang-section {
  text-align: center;
  padding: 36px 24px;
}

.slang-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.badge-mini {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-rose);
  background: rgba(244, 63, 94, 0.1);
  padding: 4px 10px;
  border-radius: 999px;
}

.slang-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-muted);
}

.slang-display {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: #fff;
  min-height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.slang-definition {
  font-size: 0.95rem;
  color: var(--text-muted);
  max-width: 500px;
  min-height: 44px;
}

/* PSA Banner */
.psa-banner {
  display: flex;
  gap: 18px;
  align-items: center;
  background: linear-gradient(135deg, rgba(244, 63, 94, 0.12), rgba(168, 85, 247, 0.08));
  border: 1px solid rgba(244, 63, 94, 0.25);
  border-radius: var(--radius-md);
  padding: 24px;
}

.psa-icon {
  font-size: 2.2rem;
  flex-shrink: 0;
}

.psa-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 4px;
}

.psa-text {
  font-size: 0.88rem;
  color: #e2e8f0;
  line-height: 1.5;
}

/* FAQ */
.faq-section {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--bg-card-border);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  cursor: pointer;
  transition: border-color 0.2s ease;
}

.faq-item:hover {
  border-color: rgba(255, 255, 255, 0.14);
}

.faq-question {
  font-weight: 700;
  font-size: 0.95rem;
  color: #fff;
  outline: none;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: "+";
  font-size: 1.2rem;
  color: var(--accent-pink);
  transition: transform 0.2s ease;
}

.faq-item[open] .faq-question::after {
  transform: rotate(45deg);
}

.faq-answer {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-top: 10px;
  line-height: 1.5;
}

/* Footer */
.site-footer {
  text-align: center;
  padding: 24px;
  border-top: 1px solid var(--bg-card-border);
  font-size: 0.8rem;
  color: var(--text-dim);
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
  .site-header {
    padding: 14px 18px;
  }
  .main-title {
    font-size: 1.7rem;
  }
  .canvas-card {
    height: 380px;
  }
  .control-row {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .sliders-row {
    grid-template-columns: 1fr;
  }
  .header-actions .btn-text {
    display: none;
  }
  .psa-banner {
    flex-direction: column;
    text-align: center;
  }
}