/* ═══════════════════════════════════════════════════
   INSIGHT ENGINE — Premium Dark Design System
   ═══════════════════════════════════════════════════ */

/* ─── Tokens ─── */
:root {
  --bg-deep:    #0a0a0f;
  --bg-surface: #12121a;
  --bg-card:    #1a1a26;
  --bg-card-hover: #22222f;
  --border:     rgba(255,255,255,0.06);
  --border-hover: rgba(255,255,255,0.12);

  --text-primary:   #f0f0f5;
  --text-secondary: #9898a8;
  --text-muted:     #5a5a6e;

  --accent-1: #7c6aef;
  --accent-2: #c06aef;
  --accent-3: #ef6a9a;

  --gradient-brand: linear-gradient(135deg, var(--accent-1), var(--accent-2), var(--accent-3));
  --gradient-glow:  radial-gradient(ellipse at 50% 0%, rgba(124,106,239,0.15) 0%, transparent 60%);

  --shadow-color: rgba(124,106,239,0.08);
  --modal-overlay: rgba(5,5,10,0.85);
  --btn-bg: rgba(255,255,255,0.06);
  --btn-bg-hover: rgba(255,255,255,0.1);
  --share-bg: rgba(255,255,255,0.05);
  --share-hover-x: rgba(255,255,255,0.1);
  --share-icon-x: #f5f5f5;
  --success-color: #4ade80;
  --success-border: rgba(74, 222, 128, 0.2);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;

  --font-sans:  'Inter', system-ui, -apple-system, sans-serif;
  --font-serif: 'Playfair Display', Georgia, serif;

  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
}

[data-theme="light"] {
  --bg-deep:    #f9fafb;
  --bg-surface: #ffffff;
  --bg-card:    #ffffff;
  --bg-card-hover: #f3f4f6;
  --border:     rgba(0,0,0,0.08);
  --border-hover: rgba(0,0,0,0.15);

  --text-primary:   #111827;
  --text-secondary: #4b5563;
  --text-muted:     #6b7280;

  --gradient-glow:  radial-gradient(ellipse at 50% 0%, rgba(124,106,239,0.08) 0%, transparent 60%);

  --shadow-color: rgba(0,0,0,0.06);
  --modal-overlay: rgba(255,255,255,0.85);
  --btn-bg: rgba(0,0,0,0.04);
  --btn-bg-hover: rgba(0,0,0,0.08);
  --share-bg: rgba(0,0,0,0.03);
  --share-hover-x: rgba(0,0,0,0.08);
  --share-icon-x: #000000;
  --success-color: #16a34a;
  --success-border: rgba(22, 163, 74, 0.2);
}

/* ─── Reset ─── */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }
body {
  font-family: var(--font-sans);
  background: var(--bg-deep);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
}

/* ─── Ambient background ─── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background: var(--gradient-glow);
  pointer-events: none;
  z-index: 0;
}

/* ═══════════════ THEME TOGGLE ═══════════════ */
.theme-toggle {
  position: absolute;
  top: 2rem;
  right: 2rem;
  z-index: 100;
  background: var(--btn-bg);
  border: 1px solid var(--border);
  color: var(--text-primary);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s var(--ease-out);
}
.theme-toggle:hover {
  background: var(--btn-bg-hover);
  transform: scale(1.05);
}
.theme-toggle .icon-moon { display: none; }
[data-theme="light"] .theme-toggle .icon-sun { display: none; }
[data-theme="light"] .theme-toggle .icon-moon { display: block; }

/* ═══════════════ NAV BACK ═══════════════ */
.nav-back {
  position: absolute;
  top: 2rem;
  left: 2rem;
  z-index: 100;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: color 0.3s var(--ease-out);
}
.nav-back:hover {
  color: var(--text-primary);
}
.nav-back svg {
  transition: transform 0.3s var(--ease-spring);
}
.nav-back:hover svg {
  transform: translateX(-4px);
}

/* ═══════════════ HERO ═══════════════ */
#hero {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 2rem;
  text-align: center;
  z-index: 1;
}

.hero-glow {
  position: absolute;
  top: -30%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(124,106,239,0.12) 0%, rgba(192,106,239,0.06) 40%, transparent 70%);
  pointer-events: none;
  animation: pulseGlow 6s ease-in-out infinite alternate;
}

@keyframes pulseGlow {
  0%   { opacity: 0.6; transform: translateX(-50%) scale(1); }
  100% { opacity: 1;   transform: translateX(-50%) scale(1.15); }
}

.hero-content {
  max-width: 680px;
}

.hero-label {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.25em;
  color: var(--accent-1);
  margin-bottom: 1.5rem;
  text-transform: uppercase;
}

#hero h1 {
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 6vw, 4.2rem);
  font-weight: 700;
  line-height: 1.15;
  margin-bottom: 1.25rem;
}

.gradient-text {
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-style: italic;
}

.hero-sub {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.6;
  max-width: 500px;
  margin: 0 auto 3rem;
}

.scroll-cue {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  cursor: pointer;
  transition: color 0.3s;
  animation: floatCue 2.5s ease-in-out infinite;
}
.scroll-cue:hover { color: var(--text-secondary); }

@keyframes floatCue {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(6px); }
}

/* ═══════════════ TOPICS SECTION ═══════════════ */
#topics {
  position: relative;
  z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 2rem 1.5rem 6rem;
}

.section-header {
  text-align: center;
  margin-bottom: 3.5rem;
}

.section-header h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1rem;
  max-width: 480px;
  margin: 0 auto;
}

/* ─── Grid ─── */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.25rem;
}

/* ─── Topic Card ─── */
.topic-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.75rem 1.5rem;
  cursor: pointer;
  transition: transform 0.4s var(--ease-out),
              background 0.3s,
              border-color 0.3s,
              box-shadow 0.4s var(--ease-out);
  overflow: hidden;
}

.topic-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-brand);
  opacity: 0;
  transition: opacity 0.4s;
  border-radius: inherit;
}

.topic-card:hover {
  transform: translateY(-4px);
  background: var(--bg-card-hover);
  border-color: var(--border-hover);
  box-shadow: 0 12px 40px var(--shadow-color);
}
.topic-card:hover::before {
  opacity: 0.04;
}

.topic-card:active {
  transform: translateY(-1px) scale(0.98);
}

.card-icon {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1.1rem;
  position: relative;
  z-index: 1;
}

.card-title {
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 0.5rem;
  position: relative;
  z-index: 1;
}

.card-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.55;
  position: relative;
  z-index: 1;
}

.card-count {
  display: inline-block;
  margin-top: 1rem;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  position: relative;
  z-index: 1;
}

/* ═══════════════ MODAL ═══════════════ */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--modal-overlay);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.35s var(--ease-out), visibility 0.35s;
  padding: 1.5rem;
}
.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal {
  position: relative;
  background: var(--bg-surface);
  border: 1px solid var(--border-hover);
  border-radius: var(--radius-lg);
  max-width: 580px;
  width: 100%;
  padding: 2.5rem 2.25rem 2rem;
  transform: translateY(30px) scale(0.96);
  transition: transform 0.45s var(--ease-spring);
}
.modal-overlay.active .modal {
  transform: translateY(0) scale(1);
}

.modal-close {
  position: absolute;
  top: 1.25rem;
  right: 1.25rem;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px;
  border-radius: 6px;
  transition: color 0.2s, background 0.2s;
}
.modal-close:hover {
  color: var(--text-primary);
  background: var(--btn-bg);
}

.modal-category {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 1rem;
}

.modal-title {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 1.25rem;
}

.modal-quote {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.7;
  padding-left: 1.25rem;
  border-left: 3px solid var(--accent-1);
  margin-bottom: 1.5rem;
  font-style: italic;
}

.modal-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.tag {
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  padding: 4px 10px;
  border-radius: 100px;
  background: rgba(124,106,239,0.1);
  color: var(--accent-1);
  border: 1px solid rgba(124,106,239,0.15);
}

/* ─── Social Share ─── */
.modal-share {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.share-label {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-right: 0.25rem;
}

.share-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--share-bg);
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
}

.share-btn:hover {
  transform: translateY(-2px);
  border-color: var(--border-hover);
}

/* X (Twitter) */
#shareX:hover {
  color: var(--share-icon-x);
  background: var(--share-hover-x);
  box-shadow: 0 4px 16px var(--shadow-color);
}

/* LinkedIn */
#shareLinkedIn:hover {
  color: #0a66c2;
  background: rgba(10,102,194,0.12);
  border-color: rgba(10,102,194,0.25);
  box-shadow: 0 4px 16px rgba(10,102,194,0.15);
}

/* Facebook */
#shareFacebook:hover {
  color: #1877f2;
  background: rgba(24,119,242,0.12);
  border-color: rgba(24,119,242,0.25);
  box-shadow: 0 4px 16px rgba(24,119,242,0.15);
}

.modal-actions {
  display: flex;
  gap: 0.75rem;
}

.btn-another, .btn-copy {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
  border: none;
}

.btn-another {
  background: var(--gradient-brand);
  color: #fff;
  flex: 1;
  justify-content: center;
}
.btn-another:hover {
  box-shadow: 0 6px 24px var(--shadow-color);
  transform: translateY(-1px);
}

.btn-copy {
  background: var(--btn-bg);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}
.btn-copy:hover {
  background: var(--btn-bg-hover);
  color: var(--text-primary);
}
.btn-copy.copied {
  color: var(--success-color);
  border-color: var(--success-border);
}

/* ═══════════════ FOOTER ═══════════════ */
footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 3rem 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.82rem;
}

/* ═══════════════ APPEAR ANIMATION ═══════════════ */
.topic-card {
  opacity: 0;
  transform: translateY(24px);
  animation: cardAppear 0.6s var(--ease-out) forwards;
}

@keyframes cardAppear {
  to { opacity: 1; transform: translateY(0); }
}

/* stagger delays applied via JS */

/* ═══════════════ RESPONSIVE ═══════════════ */
@media (max-width: 640px) {
  .topics-grid {
    grid-template-columns: 1fr;
  }
  .modal {
    padding: 2rem 1.5rem 1.5rem;
  }
  .modal-title {
    font-size: 1.3rem;
  }
  .modal-actions {
    flex-direction: column;
  }
}