/* ══════════════════════════════════════════════════
   The Neon Scholar — Vibecoding Glossary Theme
   Converted from Tailwind reference to vanilla CSS
   ══════════════════════════════════════════════════ */

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

:root {
  /* Surface & Background */
  --color-bg: #040a2f;
  --color-surface: #121b4c;
  --color-surface-hover: #1d2760;
  --color-surface-dim: #070f38;
  --color-surface-high: #172056;
  --color-surface-lowest: #000000;

  /* Text */
  --color-text: #e2e3ff;
  --color-text-muted: #a3a8d5;

  /* Accent: Secondary (Purple) */
  --color-primary: #af88ff;
  --color-primary-dim: #8a4cfc;
  --color-primary-deep: #6001d1;
  --color-on-primary: #2b0065;

  /* Accent: Tertiary (Neon Cyan) */
  --color-tertiary: #a1ffef;
  --color-tertiary-dim: #5ae4d0;

  /* Border */
  --color-border: #3f456c;
  --color-outline: #6d739d;

  /* Category Colors */
  --color-ai: #af88ff;
  --color-prompt: #dae2fd;
  --color-tools: #a1ffef;

  /* Level Colors */
  --color-level-beginner: #5de7d3;
  --color-level-basic: #af88ff;
  --color-level-advanced: #ff716c;

  /* Typography */
  --font-headline: 'Space Grotesk', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-body: 'Manrope', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-label: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.25rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;
  --font-size-4xl: 3.5rem;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 300ms ease;
  --transition-slow: 500ms ease;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
}

::selection {
  background: var(--color-tertiary);
  color: #005b51;
}

/* ── Hero Section ── */
.hero {
  position: relative;
  text-align: center;
  padding: var(--space-3xl) var(--space-lg) var(--space-2xl);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -20%;
  left: -10%;
  width: 60%;
  height: 80%;
  border-radius: 50%;
  background: rgba(93, 231, 211, 0.05);
  filter: blur(120px);
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -10%;
  right: -5%;
  width: 50%;
  height: 70%;
  border-radius: 50%;
  background: rgba(175, 136, 255, 0.05);
  filter: blur(120px);
  pointer-events: none;
}

.hero__container {
  max-width: 720px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero__title {
  font-family: var(--font-headline);
  font-size: var(--font-size-4xl);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 0.95;
  margin-bottom: var(--space-lg);
  color: var(--color-tertiary);
  text-shadow: 0 0 40px rgba(161, 255, 239, 0.3);
}

.hero__subtitle {
  font-family: var(--font-headline);
  font-size: var(--font-size-xl);
  font-weight: 500;
  color: var(--color-primary);
  margin-bottom: var(--space-xl);
  letter-spacing: -0.02em;
}

.hero__description {
  font-size: var(--font-size-base);
  color: var(--color-text-muted);
  line-height: 1.9;
  max-width: 560px;
  margin: 0 auto;
}

/* ── Main Content ── */
.main {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
}

/* ── Search Bar ── */
.search {
  margin-bottom: var(--space-xl);
}

.search__wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.search__icon {
  position: absolute;
  left: var(--space-lg);
  color: var(--color-outline);
  pointer-events: none;
  transition: color var(--transition-fast);
}

.search__input {
  width: 100%;
  padding: 1rem 1.25rem 1rem 3.25rem;
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background: rgba(23, 32, 86, 0.6);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.search__input::placeholder {
  color: var(--color-outline);
}

.search__input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(175, 136, 255, 0.15), 0 0 20px rgba(175, 136, 255, 0.1);
}

.search__input:focus ~ .search__icon,
.search__wrapper:focus-within .search__icon {
  color: var(--color-primary);
}

/* ── Category Tabs ── */
.tabs {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  padding-bottom: var(--space-xs);
}

.tabs::-webkit-scrollbar {
  display: none;
}

.tabs__btn {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.625rem 1.25rem;
  font-family: var(--font-headline);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  background: rgba(23, 32, 86, 0.4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  cursor: pointer;
  white-space: nowrap;
  letter-spacing: -0.01em;
  transition: all var(--transition-fast);
}

.tabs__btn:hover {
  color: var(--color-text);
  background: var(--color-surface-hover);
  border-color: var(--color-outline);
}

.tabs__btn--active {
  color: var(--color-on-primary);
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dim));
  border-color: transparent;
  box-shadow: 0 0 20px rgba(175, 136, 255, 0.25);
}

.tabs__btn--active:hover {
  color: var(--color-on-primary);
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dim));
}

.tabs__icon {
  font-size: var(--font-size-sm);
}

/* ── Level Filters ── */
.filters {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
  flex-wrap: wrap;
}

.filters__btn {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.375rem 0.875rem;
  font-family: var(--font-label);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filters__btn:hover {
  color: var(--color-text);
  border-color: var(--color-outline);
}

.filters__btn--active {
  color: var(--color-text);
  border-color: var(--color-text);
  background: rgba(226, 227, 255, 0.08);
}

.filters__dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  display: inline-block;
  box-shadow: 0 0 6px currentColor;
}

.filters__dot--beginner {
  background: var(--color-level-beginner);
  box-shadow: 0 0 6px rgba(93, 231, 211, 0.5);
}
.filters__dot--basic {
  background: var(--color-level-basic);
  box-shadow: 0 0 6px rgba(175, 136, 255, 0.5);
}
.filters__dot--advanced {
  background: var(--color-level-advanced);
  box-shadow: 0 0 6px rgba(255, 113, 108, 0.5);
}

/* ── Result Counter ── */
.counter {
  font-family: var(--font-label);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-outline);
  margin-bottom: var(--space-lg);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

/* ── Card List ── */
.cards {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

/* ── Term Card (Glass Card) ── */
.card {
  background: rgba(23, 32, 86, 0.6);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(63, 69, 108, 0.6);
  border-radius: var(--radius-xl);
  overflow: hidden;
  transition: border-color var(--transition-normal), box-shadow var(--transition-normal), transform var(--transition-fast);
}

.card:hover {
  border-color: var(--color-outline);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
  transform: translateY(-1px);
}

.card__header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-lg) var(--space-xl);
  cursor: pointer;
  user-select: none;
}

.card__header:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
  border-radius: var(--radius-xl);
}

.card__badge {
  flex-shrink: 0;
  padding: 0.2rem 0.625rem;
  font-family: var(--font-label);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  border-radius: var(--radius-sm);
  color: #fff;
}

.card__badge--beginner {
  background: linear-gradient(135deg, #5de7d3, #00b89c);
  color: #003d35;
  box-shadow: 0 0 10px rgba(93, 231, 211, 0.25);
}
.card__badge--basic {
  background: linear-gradient(135deg, #af88ff, #8a4cfc);
  color: #1a0040;
  box-shadow: 0 0 10px rgba(175, 136, 255, 0.25);
}
.card__badge--advanced {
  background: linear-gradient(135deg, #ff716c, #d7383b);
  color: #2d0000;
  box-shadow: 0 0 10px rgba(255, 113, 108, 0.25);
}

.card__info {
  flex: 1;
  min-width: 0;
}

.card__term {
  font-family: var(--font-headline);
  font-size: var(--font-size-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.2rem;
  color: var(--color-text);
}

.card__term-ko {
  font-family: var(--font-body);
  font-size: var(--font-size-sm);
  color: var(--color-outline);
  margin-left: var(--space-sm);
  font-weight: 400;
}

.card__short-def {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  line-height: 1.5;
}

.card__category-icon {
  flex-shrink: 0;
  font-size: var(--font-size-lg);
  opacity: 0.6;
  transition: opacity var(--transition-fast);
}

.card:hover .card__category-icon {
  opacity: 1;
}

.card__toggle {
  flex-shrink: 0;
  font-size: var(--font-size-sm);
  color: var(--color-outline);
  transition: transform var(--transition-normal), color var(--transition-fast);
}

.card:hover .card__toggle {
  color: var(--color-primary);
}

.card--expanded .card__toggle {
  transform: rotate(180deg);
  color: var(--color-tertiary);
}

/* ── Accordion Detail ── */
.card__detail {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-normal);
}

.card--expanded .card__detail {
  max-height: 600px;
}

.card__detail-inner {
  padding: 0 var(--space-xl) var(--space-xl);
  border-top: 1px solid rgba(63, 69, 108, 0.5);
  padding-top: var(--space-xl);
}

.card__section {
  margin-bottom: var(--space-lg);
}

.card__section:last-child {
  margin-bottom: 0;
}

.card__section-title {
  font-family: var(--font-headline);
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-tertiary-dim);
  letter-spacing: -0.01em;
}

.card__section-text {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  line-height: 1.9;
}

/* Category accent border on expanded card */
.card--expanded {
  border-left: 3px solid var(--color-primary);
}

.card--expanded[data-category="ai-basic"] {
  border-left-color: var(--color-ai);
  box-shadow: 0 0 30px rgba(175, 136, 255, 0.08);
}

.card--expanded[data-category="prompt"] {
  border-left-color: var(--color-prompt);
  box-shadow: 0 0 30px rgba(218, 226, 253, 0.06);
}

.card--expanded[data-category="tools"] {
  border-left-color: var(--color-tools);
  box-shadow: 0 0 30px rgba(161, 255, 239, 0.08);
}

/* ── Empty State ── */
.empty {
  text-align: center;
  padding: var(--space-3xl) var(--space-lg);
}

.empty__text {
  font-family: var(--font-headline);
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--color-text);
}

.empty__hint {
  font-size: var(--font-size-sm);
  color: var(--color-outline);
}

/* ── Footer ── */
.footer {
  text-align: center;
  padding: var(--space-2xl) var(--space-lg);
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  margin-top: var(--space-3xl);
}

.footer__text {
  font-family: var(--font-body);
  font-size: var(--font-size-sm);
  color: var(--color-outline);
  opacity: 0.8;
}

/* ── Responsive: Mobile ── */
@media (max-width: 768px) {
  .hero {
    padding: var(--space-2xl) var(--space-md) var(--space-xl);
  }

  .hero__title {
    font-size: var(--font-size-2xl);
  }

  .hero__subtitle {
    font-size: var(--font-size-lg);
  }

  .main {
    padding: var(--space-lg) var(--space-md);
  }

  .card__header {
    padding: var(--space-md) var(--space-lg);
  }

  .card__term {
    font-size: var(--font-size-base);
  }

  .card__term-ko {
    display: block;
    margin-left: 0;
    margin-top: 0.125rem;
  }

  .card__detail-inner {
    padding: 0 var(--space-lg) var(--space-lg);
    padding-top: var(--space-md);
  }

  .tabs__btn {
    padding: 0.5rem 1rem;
  }
}

@media (max-width: 480px) {
  .hero__title {
    font-size: var(--font-size-xl);
  }

  .hero__subtitle {
    font-size: var(--font-size-base);
  }

  .card__header {
    padding: var(--space-md);
    gap: var(--space-sm);
  }

  .card__detail-inner {
    padding: 0 var(--space-md) var(--space-md);
    padding-top: var(--space-md);
  }
}

/* ── Utility: Hidden ── */
[hidden] {
  display: none !important;
}