:root {
  color-scheme: dark;
  --bg-dark: #07090e;
  --bg-card: rgba(14, 19, 30, 0.88);
  --bg-card-hover: rgba(22, 30, 48, 0.95);
  --border-subtle: rgba(56, 189, 248, 0.2);
  --border-focus: #38bdf8;
  --volvo-blue: #0284c7;
  --volvo-sky: #38bdf8;
  --volvo-gold: #f59e0b;
  --volvo-amber: #fbbf24;
  --volvo-red: #ef4444;
  --volvo-green: #10b981;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 8px;
}

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

html {
  scrollbar-color: var(--volvo-sky) var(--bg-dark);
  scrollbar-width: thin;
  scroll-behavior: smooth;
}

body {
  font-family: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-main);
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
  line-height: 1.5;
}

/* Ambient Glow & Canvas */
.volvo-glow {
  position: fixed;
  border-radius: 50%;
  filter: blur(140px);
  pointer-events: none;
  z-index: 0;
  opacity: 0.22;
}

.glow-blue {
  top: -150px;
  right: -100px;
  width: 550px;
  height: 550px;
  background: var(--volvo-sky);
}

.glow-amber {
  bottom: -150px;
  left: -100px;
  width: 500px;
  height: 500px;
  background: var(--volvo-gold);
  opacity: 0.15;
}

#bgCanvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}

/* Container */
.app-container {
  position: relative;
  z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px 20px 60px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}

/* Header */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
  flex-wrap: wrap;
  gap: 16px;
}

.brand-badge {
  display: flex;
  align-items: center;
  gap: 14px;
}

.iron-mark-icon {
  color: var(--volvo-sky);
  filter: drop-shadow(0 0 12px rgba(56, 189, 248, 0.4));
  flex-shrink: 0;
}

.brand-titles {
  display: flex;
  flex-direction: column;
}

.brand-main {
  font-size: 20px;
  font-weight: 900;
  letter-spacing: 1px;
  color: #ffffff;
}

.brand-sub {
  font-size: 12px;
  font-weight: 600;
  color: var(--volvo-sky);
  letter-spacing: 0.5px;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

.btn-ctrl {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-subtle);
  color: var(--text-main);
  padding: 8px 14px;
  border-radius: var(--radius-md);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s ease;
  font-family: inherit;
}

.btn-ctrl:hover {
  background: rgba(56, 189, 248, 0.15);
  border-color: var(--volvo-sky);
  color: #ffffff;
  transform: translateY(-2px);
}

/* Base Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 28px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.5px;
  cursor: pointer;
  border: none;
  font-family: inherit;
  transition: all 0.25s ease;
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--volvo-blue), var(--volvo-sky));
  color: #040813;
  box-shadow: 0 4px 20px rgba(56, 189, 248, 0.35);
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 30px rgba(56, 189, 248, 0.6);
  filter: brightness(1.1);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--border-subtle);
  color: var(--text-main);
}

.btn-outline:hover {
  border-color: var(--volvo-sky);
  background: rgba(56, 189, 248, 0.1);
  color: #ffffff;
}

/* Hero & Mode Selector */
.hero-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 20px;
  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(56, 189, 248, 0.12);
  border: 1px solid var(--volvo-sky);
  color: var(--volvo-sky);
  padding: 6px 16px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.5px;
}

.pulse-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--volvo-sky);
  box-shadow: 0 0 10px var(--volvo-sky);
  animation: pulseDot 2s infinite;
}

@keyframes pulseDot {
  0% { transform: scale(0.9); opacity: 0.7; }
  50% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(0.9); opacity: 0.7; }
}

.hero-title {
  font-size: clamp(26px, 4vw, 38px);
  font-weight: 900;
  line-height: 1.2;
  color: #ffffff;
  max-width: 800px;
  text-wrap: balance;
}

.hero-desc {
  color: var(--text-muted);
  font-size: 16px;
  max-width: 760px;
  line-height: 1.6;
  text-wrap: balance;
}

.hero-desc strong {
  color: #ffffff;
}

/* Mode Selection Cards Grid */
.mode-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
  width: 100%;
  margin-top: 10px;
}

.mode-card {
  background: rgba(11, 15, 25, 0.75);
  border: 2px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 22px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  text-align: left;
  gap: 12px;
  cursor: pointer;
  position: relative;
  transition: all 0.25s ease;
  user-select: none;
}

.mode-card:hover {
  transform: translateY(-4px);
  border-color: rgba(56, 189, 248, 0.4);
  background: var(--bg-card-hover);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
}

.mode-card.active {
  border-color: var(--volvo-sky);
  background: rgba(56, 189, 248, 0.08);
  box-shadow: 0 0 25px rgba(56, 189, 248, 0.25);
}

.mode-popular {
  position: absolute;
  top: -10px;
  right: 14px;
  background: linear-gradient(135deg, var(--volvo-gold), #ea580c);
  color: #000;
  font-size: 10px;
  font-weight: 900;
  padding: 3px 8px;
  border-radius: 6px;
  letter-spacing: 0.5px;
}

.mode-icon {
  font-size: 32px;
}

.mode-info h3 {
  font-size: 16px;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 4px;
}

.mode-info p {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.4;
  margin-bottom: 8px;
}

.mode-tag {
  font-size: 11px;
  font-weight: 700;
  color: var(--volvo-sky);
  background: rgba(56, 189, 248, 0.12);
  padding: 2px 8px;
  border-radius: 6px;
}

.hero-start-wrap {
  margin-top: 10px;
}

/* Active Quiz Card */
.quiz-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  gap: 24px;
  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  position: relative;
}

.quiz-header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px;
}

.q-progress-info {
  display: flex;
  align-items: center;
  gap: 12px;
}

.q-counter-label {
  font-size: 14px;
  font-weight: 800;
  color: var(--text-muted);
}

.q-category-badge {
  font-size: 12px;
  font-weight: 800;
  color: var(--volvo-sky);
  background: rgba(56, 189, 248, 0.12);
  border: 1px solid var(--border-subtle);
  padding: 4px 10px;
  border-radius: 8px;
  letter-spacing: 0.5px;
}

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

.q-timer-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(239, 68, 68, 0.15);
  border: 1px solid var(--volvo-red);
  color: #f87171;
  padding: 4px 12px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 800;
  font-family: 'Fira Code', monospace;
}

.q-timer-badge.urgent {
  animation: pulseUrgent 0.8s infinite alternate;
}

@keyframes pulseUrgent {
  0% { transform: scale(1); filter: brightness(1); }
  100% { transform: scale(1.08); filter: brightness(1.4); }
}

.q-score-badge, .q-streak-badge {
  font-size: 13px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 6px;
  background: rgba(255, 255, 255, 0.05);
  padding: 4px 10px;
  border-radius: 8px;
}

.q-score-badge strong {
  color: var(--volvo-sky);
  font-size: 15px;
}

.q-streak-badge strong {
  color: var(--volvo-gold);
  font-size: 15px;
}

/* Progress Track */
.progress-track {
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--volvo-blue), var(--volvo-sky));
  transition: width 0.3s ease;
  box-shadow: 0 0 12px var(--volvo-sky);
}

.question-body {
  margin: 8px 0;
}

.question-title {
  font-size: clamp(19px, 2.8vw, 24px);
  font-weight: 800;
  line-height: 1.4;
  color: #ffffff;
  text-wrap: balance;
}

/* Options Grid */
.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

.option-btn {
  background: rgba(11, 15, 25, 0.75);
  border: 2px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  color: var(--text-main);
  font-size: 16px;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.2s ease;
  user-select: none;
}

.option-btn:hover:not(:disabled) {
  background: var(--bg-card-hover);
  border-color: var(--volvo-sky);
  transform: translateX(4px);
}

.option-letter {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 800;
  color: var(--volvo-sky);
  flex-shrink: 0;
}

.option-btn.correct {
  background: rgba(16, 185, 129, 0.15) !important;
  border-color: var(--volvo-green) !important;
  color: #ffffff !important;
}

.option-btn.correct .option-letter {
  background: var(--volvo-green);
  color: #000000;
}

.option-btn.wrong {
  background: rgba(239, 68, 68, 0.15) !important;
  border-color: var(--volvo-red) !important;
  color: #ffffff !important;
}

.option-btn.wrong .option-letter {
  background: var(--volvo-red);
  color: #ffffff;
}

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

/* Explanation Box */
.explanation-box {
  background: rgba(2, 132, 199, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.3);
  border-radius: var(--radius-md);
  padding: 18px 20px;
  display: flex;
  gap: 16px;
  animation: fadeIn 0.3s ease;
}

.exp-icon {
  font-size: 28px;
  flex-shrink: 0;
}

.exp-content h4 {
  font-size: 14px;
  font-weight: 800;
  color: var(--volvo-sky);
  margin-bottom: 4px;
  letter-spacing: 0.5px;
}

.exp-content p {
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.5;
}

.quiz-actions {
  display: flex;
  justify-content: flex-end;
  animation: fadeIn 0.3s ease;
}

/* Results Section */
.results-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 48px 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 20px;
  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  animation: fadeIn 0.4s ease;
}

.results-badge {
  font-size: 13px;
  font-weight: 800;
  color: var(--volvo-gold);
  background: rgba(245, 158, 11, 0.12);
  border: 1px solid rgba(245, 158, 11, 0.3);
  padding: 6px 16px;
  border-radius: 999px;
  letter-spacing: 1px;
}

.trophy-icon {
  font-size: 64px;
  filter: drop-shadow(0 0 25px rgba(245, 158, 11, 0.4));
  animation: trophyBob 2s infinite alternate ease-in-out;
}

@keyframes trophyBob {
  0% { transform: translateY(0); }
  100% { transform: translateY(-8px); }
}

.results-title {
  font-size: 32px;
  font-weight: 900;
  color: #ffffff;
}

.results-rank {
  font-size: 18px;
  color: var(--text-muted);
}

.results-rank strong {
  color: var(--volvo-sky);
}

.results-stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 16px;
  width: 100%;
  max-width: 700px;
  margin: 10px 0;
}

.stat-box {
  background: rgba(11, 15, 25, 0.75);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.stat-label {
  font-size: 12px;
  font-weight: 700;
  color: var(--text-dim);
  text-transform: uppercase;
}

.stat-val {
  font-size: 24px;
  font-weight: 900;
  color: #ffffff;
  font-family: 'Fira Code', monospace;
}

.results-feedback {
  font-size: 15px;
  color: var(--text-muted);
  max-width: 600px;
  line-height: 1.6;
}

.results-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 10px;
}

/* Specs Section */
.specs-section {
  display: flex;
  flex-direction: column;
  gap: 20px;
  content-visibility: auto;
  contain-intrinsic-size: 600px;
}

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

.section-header h2 {
  font-size: 22px;
  font-weight: 900;
  color: var(--volvo-sky);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  text-wrap: balance;
}

.section-header p {
  color: var(--text-muted);
  font-size: 14px;
  margin-top: 4px;
}

.specs-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 18px;
}

.spec-card {
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 22px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: all 0.25s ease;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.spec-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-focus);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
}

.spec-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.spec-code {
  font-family: 'Fira Code', monospace;
  font-size: 13px;
  font-weight: 700;
  color: var(--volvo-sky);
}

.spec-pill {
  font-size: 11px;
  font-weight: 800;
  padding: 3px 8px;
  border-radius: 6px;
}

.pill-legend { background: rgba(16, 185, 129, 0.15); color: #34d399; }
.pill-warn   { background: rgba(245, 158, 11, 0.15); color: #fbbf24; }
.pill-turbo  { background: rgba(6, 182, 212, 0.15); color: #22d3ee; }
.pill-tank   { background: rgba(168, 85, 247, 0.15); color: #c084fc; }
.pill-modern { background: rgba(56, 189, 248, 0.15); color: #38bdf8; }
.pill-classic{ background: rgba(239, 68, 68, 0.15); color: #f87171; }

.spec-card h3 {
  font-size: 16px;
  font-weight: 800;
  color: #ffffff;
}

.spec-card p {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
}

.spec-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: auto;
  padding-top: 8px;
}

.spec-tags span {
  font-size: 11px;
  font-weight: 700;
  color: var(--text-dim);
  background: rgba(255, 255, 255, 0.05);
  padding: 2px 8px;
  border-radius: 6px;
}

/* Footer */
.app-footer {
  text-align: center;
  padding-top: 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  color: var(--text-dim);
  font-size: 13px;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-links a {
  color: var(--volvo-sky);
  text-decoration: none;
  font-weight: 700;
}

.footer-links a:hover {
  text-decoration: underline;
}

/* Utility */
.hidden {
  display: none !important;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 640px) {
  .app-container { padding: 16px 14px 40px; }
  .hero-card, .quiz-card, .results-card { padding: 24px 18px; }
  .app-header { padding: 14px 16px; }
  .mode-grid { grid-template-columns: 1fr; }
}