/* ==========================================================================
   QuizPulse Elite - Design System & Global Styles
   Curated modern palette, dark & light themes, glassmorphism, glowing accents
   ========================================================================== */

:root {
  /* Core Color Palette - Dark Theme (Default) */
  --bg-primary: #0a0d14;
  --bg-secondary: #0f172a;
  --bg-card: rgba(18, 24, 38, 0.75);
  --bg-card-hover: rgba(28, 36, 56, 0.85);
  --bg-input: rgba(15, 23, 42, 0.6);

  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-focus: rgba(99, 102, 241, 0.6);
  --border-glow: rgba(99, 102, 241, 0.35);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-inverse: #0f172a;

  /* Accent Vibrance */
  --accent-primary: #6366f1; /* Indigo */
  --accent-secondary: #8b5cf6; /* Violet */
  --accent-cyan: #06b6d4;
  --accent-emerald: #10b981;
  --accent-rose: #f43f5e;
  --accent-amber: #f59e0b;

  --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);
  --accent-gradient-cyan: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
  --accent-gradient-gold: linear-gradient(135deg, #f59e0b 0%, #ef4444 100%);
  --card-glass-glow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);

  /* Shadows */
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 25px rgba(99, 102, 241, 0.45);
  --shadow-glow-success: 0 0 25px rgba(16, 185, 129, 0.4);
  --shadow-glow-danger: 0 0 25px rgba(244, 63, 94, 0.4);

  /* Dimensions & Radius */
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-pill: 9999px;

  /* Fonts */
  --font-main: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Transitions */
  --transition-fast: 0.18s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme Variables */
[data-theme='light'] {
  --bg-primary: #f8fafc;
  --bg-secondary: #f1f5f9;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-hover: rgba(255, 255, 255, 0.98);
  --bg-input: rgba(241, 245, 249, 0.9);

  --border-subtle: rgba(0, 0, 0, 0.08);
  --border-focus: rgba(99, 102, 241, 0.8);
  --border-glow: rgba(99, 102, 241, 0.2);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-inverse: #f8fafc;

  --card-glass-glow: 0 8px 30px 0 rgba(99, 102, 241, 0.08);
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.12);
}

/* Base Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-main);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  -webkit-font-smoothing: antialiased;
}

/* Ambient Background Lights */
.ambient-glow {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}

.glow-orb-1 {
  position: absolute;
  top: -10vw;
  left: 15vw;
  width: 45vw;
  height: 45vw;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.18) 0%, rgba(99, 102, 241, 0) 70%);
  filter: blur(60px);
  animation: floatOrb 18s ease-in-out infinite alternate;
}

.glow-orb-2 {
  position: absolute;
  bottom: -15vw;
  right: 5vw;
  width: 50vw;
  height: 50vw;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(236, 72, 153, 0.15) 0%, rgba(236, 72, 153, 0) 70%);
  filter: blur(80px);
  animation: floatOrb 22s ease-in-out infinite alternate-reverse;
}

.glow-orb-3 {
  position: absolute;
  top: 40vh;
  left: -10vw;
  width: 35vw;
  height: 35vw;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(6, 182, 212, 0.12) 0%, rgba(6, 182, 212, 0) 70%);
  filter: blur(70px);
  animation: floatOrb 26s ease-in-out infinite alternate;
}

/* App Wrapper */
.app-container {
  position: relative;
  z-index: 1;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem 3rem 1.5rem;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Navigation Header */
.main-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--border-subtle);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 13, 20, 0.6);
}

[data-theme='light'] .main-header {
  background: rgba(248, 250, 252, 0.7);
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  cursor: pointer;
}

.brand-logo-icon {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-md);
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}

.brand-text h1 {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.1;
}

.brand-tagline {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* Header User Stats Pill */
.user-profile-badge {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.45rem 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-pill);
  font-size: 0.85rem;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(10px);
}

.user-level {
  background: var(--accent-gradient-cyan);
  color: #fff;
  padding: 0.15rem 0.6rem;
  border-radius: var(--radius-pill);
  font-weight: 700;
  font-size: 0.75rem;
}

.user-rank {
  font-weight: 600;
  color: var(--text-secondary);
}

.user-xp {
  font-weight: 700;
  color: var(--accent-amber);
}

/* Header Controls */
.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.btn-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-pill);
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 1.15rem;
  box-shadow: var(--shadow-sm);
}

.btn-icon:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-focus);
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}

.btn-nav {
  padding: 0.5rem 1.1rem;
  border-radius: var(--radius-pill);
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-size: 0.88rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.45rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-nav:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}

/* ==========================================================================
   Home Screen Layout
   ========================================================================== */
.screen {
  flex: 1;
  padding-top: 2rem;
  animation: fadeIn 0.35s ease-out;
}

.hidden {
  display: none !important;
}

/* Hero Section */
.hero-banner {
  text-align: center;
  margin-bottom: 2.75rem;
  position: relative;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1.1rem;
  background: rgba(99, 102, 241, 0.12);
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: var(--radius-pill);
  color: var(--accent-primary);
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
}

.hero-title span {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 2rem auto;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn-primary {
  padding: 0.85rem 2rem;
  background: var(--accent-gradient);
  color: #fff;
  border: none;
  border-radius: var(--radius-pill);
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-primary:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: 0 6px 28px rgba(99, 102, 241, 0.6);
}

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

.btn-secondary {
  padding: 0.85rem 1.8rem;
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-pill);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
}

/* Section Titles */
.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
}

.section-title {
  font-size: 1.4rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.section-subtitle {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Category Grid */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2.5rem;
}

.category-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.35rem;
  cursor: pointer;
  transition: all var(--transition-normal);
  backdrop-filter: blur(16px);
  box-shadow: var(--card-glass-glow);
  display: flex;
  align-items: flex-start;
  gap: 1.1rem;
  overflow: hidden;
}

.category-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-focus);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}

.category-card.selected {
  border-color: var(--accent-primary);
  background: rgba(99, 102, 241, 0.12);
  box-shadow: 0 0 25px rgba(99, 102, 241, 0.35);
}

.category-icon-wrapper {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.category-details {
  flex: 1;
}

.category-header-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.3rem;
}

.category-title {
  font-size: 1.05rem;
  font-weight: 700;
}

.category-count {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-secondary);
}

.category-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

.category-check {
  display: none;
  position: absolute;
  top: 1rem;
  right: 1rem;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--accent-primary);
  color: #fff;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: bold;
}

.category-card.selected .category-check {
  display: flex;
}

/* Configurator Panels */
.configurator-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: 1.75rem 2rem;
  backdrop-filter: blur(16px);
  margin-bottom: 3rem;
  box-shadow: var(--card-glass-glow);
}

.config-row {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.config-label {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.pill-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.filter-pill {
  padding: 0.55rem 1.25rem;
  border-radius: var(--radius-pill);
  background: var(--bg-input);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filter-pill:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--border-focus);
}

.filter-pill.active {
  background: var(--accent-primary);
  color: #fff;
  border-color: var(--accent-primary);
  box-shadow: 0 2px 10px rgba(99, 102, 241, 0.4);
}

.start-action-row {
  display: flex;
  justify-content: flex-end;
  padding-top: 1rem;
  border-top: 1px solid var(--border-subtle);
}

/* Footer */
.app-footer {
  margin-top: auto;
  padding: 2rem 0 1rem 0;
  border-top: 1px solid var(--border-subtle);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
}

.footer-badges {
  display: flex;
  gap: 0.6rem;
  margin-top: 0.4rem;
}

.footer-tag {
  font-size: 0.75rem;
  padding: 0.15rem 0.6rem;
  border-radius: var(--radius-pill);
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
}