/* ── CSS Variables ─────────────────────────────────────────── */
:root {
  --bg: #0a0a12;
  --surface: #12121e;
  --surface2: #1a1a2e;
  --border: rgba(255,255,255,0.08);
  --border-hover: rgba(255,255,255,0.16);
  --text: #f0f0ff;
  --text-muted: #8b8ba8;
  --text-dim: #4a4a68;
  --accent: #7c6ff7;
  --accent2: #a78bfa;
  --accent-glow: rgba(124,111,247,0.3);
  --accent-hover: #6c5fe6;
  --danger: #f56565;
  --success: #48bb78;
  --warning: #f6ad55;
  --radius: 16px;
  --radius-sm: 8px;
  --radius-lg: 24px;
  --shadow-sm: 0 1px 4px rgba(0,0,0,0.4);
  --shadow-md: 0 4px 24px rgba(0,0,0,0.5);
  --shadow-lg: 0 8px 48px rgba(0,0,0,0.6);
  --shadow-glow: 0 0 40px rgba(124,111,247,0.15);
  --transition: 0.22s cubic-bezier(0.4, 0, 0.2, 1);
  --font: 'Inter', system-ui, -apple-system, sans-serif;
  --bg-glass: rgba(10,10,18,0.85);
  --bg-overlay: rgba(10,10,18,0.92);
  --bg-topbar: rgba(10,10,18,0.9);
  --hero-badge-bg: rgba(255,255,255,0.04);
  --hero-badge-bg-hover: rgba(255,255,255,0.07);
  --surface-subtle: rgba(255,255,255,0.04);
  --btn-secondary-bg: rgba(255,255,255,0.06);
  --btn-secondary-hover: rgba(255,255,255,0.1);
  --input-bg: rgba(255,255,255,0.04);
}

[data-theme='light'] {
  --bg: #ffffff;
  --surface: #f8fafc;
  --surface2: #f1f5f9;
  --border: rgba(0,0,0,0.1);
  --border-hover: rgba(0,0,0,0.2);
  --text: #0f172a;
  --text-muted: #475569;
  --text-dim: #64748b;
  --accent: #4f46e5;
  --accent2: #8b5cf6;
  --accent-glow: rgba(79,70,229,0.3);
  --accent-hover: #4338ca;
  --shadow-sm: 0 1px 4px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 48px rgba(0,0,0,0.12);
  --shadow-glow: 0 0 40px rgba(79,70,229,0.15);
  --bg-glass: rgba(255,255,255,0.9);
  --bg-overlay: rgba(248,250,252,0.95);
  --bg-topbar: rgba(255,255,255,0.92);
  --hero-badge-bg: rgba(0,0,0,0.03);
  --hero-badge-bg-hover: rgba(0,0,0,0.06);
  --mesh-1: rgba(79,70,229,0.06);
  --mesh-2: rgba(139,92,246,0.04);
  --mesh-3: rgba(99,102,241,0.03);
  --surface-subtle: rgba(0,0,0,0.03);
  --btn-secondary-bg: rgba(0,0,0,0.05);
  --btn-secondary-hover: rgba(0,0,0,0.09);
  --input-bg: rgba(0,0,0,0.03);
}

/* ── Section gradient heading ──────────────────────────────── */
.section-heading-gradient {
  background: linear-gradient(135deg, var(--text), var(--accent2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* ── Light mode text/gradient overrides ────────────────────── */
[data-theme='light'] .hero h1 {
  background: linear-gradient(160deg, var(--accent) 0%, #a855f7 60%, #ec4899 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

[data-theme='light'] .navbar-brand {
  background: linear-gradient(135deg, #4f46e5, #7c3aed, #9333ea);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

[data-theme='light'] .navbar-brand span {
  opacity: 1;
  font-weight: 800;
}

[data-theme='light'] .section-heading-gradient {
  background: linear-gradient(135deg, var(--accent) 0%, #a855f7 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
/* ── Reset ─────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

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

/* ── Background Mesh ───────────────────────────────────────── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 20% 10%, var(--mesh-1, rgba(124,111,247,0.08)) 0%, transparent 60%),
    radial-gradient(ellipse 60% 40% at 80% 80%, var(--mesh-2, rgba(167,139,250,0.06)) 0%, transparent 50%),
    radial-gradient(ellipse 40% 30% at 50% 50%, var(--mesh-3, rgba(99,102,241,0.04)) 0%, transparent 60%);
  pointer-events: none;
  z-index: 0;
}

body > * { position: relative; z-index: 1; }

/* ── Nav Links ─────────────────────────────────────────────── */
.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  transition: color 0.2s, background 0.2s;
}

.nav-links a:hover {
  color: var(--text);
  background: rgba(255,255,255,0.06);
}

[data-theme='light'] .nav-links a:hover {
  background: rgba(0,0,0,0.05);
}

@media (max-width: 680px) {
  .nav-links { display: none; }
}

/* ── Typography ────────────────────────────────────────────── */
h1, h2, h3 { line-height: 1.2; font-weight: 700; }
a { color: var(--accent2); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent); }

/* ── Layout ────────────────────────────────────────────────── */
.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ── Navbar ────────────────────────────────────────────────── */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2rem;
  background: var(--bg-glass);
  backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar-brand {
  font-size: 1.35rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent2), #c4b5fd);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

.navbar-brand span {
  font-weight: 800;
  opacity: 1;
}

.theme-toggle {
  background: transparent;
  border: none;
  padding: 0;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.45rem;
  outline: none;
}

.toggle-icon {
  display: flex;
  align-items: center;
  color: var(--text-muted);
  transition: color var(--transition), transform var(--transition);
  flex-shrink: 0;
}

.icon-sun, .icon-moon {
  transition: opacity var(--transition), transform var(--transition);
  position: absolute;
}

.icon-sun { opacity: 1; transform: scale(1) rotate(0deg); }
.icon-moon { opacity: 0; transform: scale(0.5) rotate(-30deg); }

[data-theme='light'] .icon-sun { opacity: 0; transform: scale(0.5) rotate(30deg); }
[data-theme='light'] .icon-moon { opacity: 1; transform: scale(1) rotate(0deg); }

.toggle-icon { position: relative; width: 14px; height: 14px; }

.toggle-track {
  width: 44px;
  height: 24px;
  background: var(--surface2);
  border: 1.5px solid var(--border);
  border-radius: 999px;
  position: relative;
  transition: background var(--transition), border-color var(--transition), box-shadow var(--transition);
  display: flex;
  align-items: center;
}

[data-theme='light'] .toggle-track {
  background: var(--accent);
  border-color: var(--accent);
  box-shadow: 0 0 10px var(--accent-glow);
}

.toggle-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--text-muted);
  position: absolute;
  left: 2px;
  transition: transform var(--transition), background var(--transition), box-shadow var(--transition);
  box-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

[data-theme='light'] .toggle-thumb {
  transform: translateX(20px);
  background: white;
  box-shadow: 0 1px 6px rgba(0,0,0,0.2);
}

.theme-toggle:hover .toggle-track {
  border-color: var(--border-hover);
}

.theme-toggle:hover .toggle-thumb {
  background: var(--text);
}

[data-theme='light'] .theme-toggle:hover .toggle-thumb {
  background: white;
}

/* ── Hero ──────────────────────────────────────────────────── */
.hero {
  text-align: center;
  padding: 5rem 1.5rem 3rem;
  position: relative;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(124,111,247,0.12);
  border: 1px solid rgba(124,111,247,0.25);
  border-radius: 999px;
  padding: 0.35rem 1rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent2);
  margin-bottom: 1.5rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(2.2rem, 6vw, 3.8rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  margin-bottom: 1.25rem;
  background: linear-gradient(160deg, var(--text) 0%, var(--accent2) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.1;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 520px;
  margin: 0 auto 1.5rem;
  line-height: 1.7;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--hero-badge-bg);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.35rem 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  transition: all var(--transition);
}

.hero-badge:hover {
  background: var(--hero-badge-bg-hover);
  border-color: var(--border-hover);
}

.hero-badge .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--success);
  box-shadow: 0 0 8px rgba(72,187,120,0.6);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

/* ── Upload Zone ───────────────────────────────────────────── */
.upload-section {
  padding: 0 1.5rem 2.5rem;
}

.upload-zone {
  border: 2px dashed rgba(124,111,247,0.25);
  border-radius: var(--radius-lg);
  padding: 3.5rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: rgba(124,111,247,0.04);
  position: relative;
  overflow: hidden;
}

.upload-zone::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at center, rgba(124,111,247,0.06) 0%, transparent 70%);
  opacity: 0;
  transition: opacity var(--transition);
}

.upload-zone:hover::before,
.upload-zone.drag-over::before {
  opacity: 1;
}

.upload-zone:hover,
.upload-zone.drag-over {
  border-color: var(--accent);
  background: rgba(124,111,247,0.08);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow);
}

.upload-zone.drag-over {
  border-style: solid;
  border-color: var(--accent2);
}

.upload-icon {
  font-size: 3.5rem;
  margin-bottom: 1.25rem;
  display: block;
  filter: drop-shadow(0 4px 12px rgba(124,111,247,0.3));
}

.upload-zone h3 {
  font-size: 1.15rem;
  margin-bottom: 0.5rem;
  color: var(--text);
  font-weight: 600;
}

.upload-zone p {
  color: var(--text-muted);
  font-size: 0.92rem;
}

.upload-zone p strong {
  color: var(--accent2);
}

.upload-zone p.file-types {
  margin-top: 0.75rem;
  font-size: 0.78rem;
  color: var(--text-dim);
  background: var(--surface-subtle);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.25rem 0.875rem;
  display: inline-block;
}

.file-selected {
  display: none;
  align-items: center;
  gap: 0.75rem;
  background: rgba(124,111,247,0.1);
  border: 1px solid rgba(124,111,247,0.3);
  border-radius: var(--radius-sm);
  padding: 0.875rem 1.25rem;
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--accent2);
}

.file-selected.show { display: flex; }

.file-selected .remove-file {
  margin-left: auto;
  cursor: pointer;
  opacity: 0.6;
  transition: opacity var(--transition);
  background: none;
  border: none;
  font-size: 1.1rem;
  color: var(--accent2);
}

.file-selected .remove-file:hover { opacity: 1; }

/* ── Theme Selector ────────────────────────────────────────── */
.theme-section {
  padding: 0 1.5rem 2.5rem;
}

.theme-section h2 {
  font-size: 0.75rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.theme-section h2::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

.theme-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(145px, 1fr));
  gap: 0.75rem;
}

.theme-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--surface);
  position: relative;
  overflow: hidden;
}

.theme-card::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity var(--transition);
  background: radial-gradient(ellipse at 50% 0%, rgba(124,111,247,0.12) 0%, transparent 70%);
}

.theme-card:hover {
  border-color: var(--border-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}

.theme-card:hover::before { opacity: 1; }

.theme-card.selected {
  border-color: var(--accent);
  background: rgba(124,111,247,0.1);
  box-shadow: 0 0 0 1px var(--accent), var(--shadow-glow);
}

.theme-card.selected::after {
  content: '✓';
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  width: 20px;
  height: 20px;
  background: var(--accent);
  color: white;
  border-radius: 50%;
  font-size: 0.65rem;
  display: grid;
  place-items: center;
  font-weight: 700;
}

.theme-swatch {
  height: 56px;
  border-radius: 8px;
  margin-bottom: 0.75rem;
  overflow: hidden;
  display: flex;
  box-shadow: inset 0 0 0 1px rgba(0,0,0,0.1);
}

.theme-swatch-block { flex: 1; }

.theme-name {
  font-size: 0.85rem;
  font-weight: 700;
  display: block;
  margin-bottom: 0.2rem;
  color: var(--text);
}

.theme-desc {
  font-size: 0.73rem;
  color: var(--text-muted);
  display: block;
}

/* ── Convert Button ────────────────────────────────────────── */
.convert-section {
  padding: 0 1.5rem 3.5rem;
  text-align: center;
}

.btn-convert {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent2) 60%, #c4b5fd 100%);
  color: white;
  border: none;
  border-radius: 999px;
  padding: 1rem 3.5rem;
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: 0 4px 24px rgba(124,111,247,0.4), 0 0 0 1px rgba(124,111,247,0.2);
  letter-spacing: 0.02em;
  position: relative;
  overflow: hidden;
}

.btn-convert::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.15) 0%, transparent 50%);
  opacity: 0;
  transition: opacity var(--transition);
}

.btn-convert:hover:not(:disabled)::before { opacity: 1; }

.btn-convert:hover:not(:disabled) {
  transform: translateY(-3px);
  box-shadow: 0 8px 36px rgba(124,111,247,0.55), 0 0 0 1px rgba(124,111,247,0.3);
}

.btn-convert:active:not(:disabled) {
  transform: translateY(-1px);
}

.btn-convert:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  transform: none;
  filter: grayscale(0.3);
}

/* ── Loading State ─────────────────────────────────────────── */
.loading-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  backdrop-filter: blur(20px);
  z-index: 200;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2rem;
}

.loading-overlay.show { display: flex; }

.spinner {
  width: 60px;
  height: 60px;
  position: relative;
}

.spinner::before,
.spinner::after {
  content: '';
  position: absolute;
  border-radius: 50%;
  animation: spin 0.9s linear infinite;
}

.spinner::before {
  inset: 0;
  border: 3px solid rgba(124,111,247,0.15);
  border-top-color: var(--accent);
}

.spinner::after {
  inset: 8px;
  border: 3px solid rgba(167,139,250,0.1);
  border-top-color: var(--accent2);
  animation-direction: reverse;
  animation-duration: 0.6s;
}

@keyframes spin { to { transform: rotate(360deg); } }

.loading-message {
  font-size: 1.05rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: opacity 0.4s ease;
  text-align: center;
}

.loading-progress {
  display: flex;
  gap: 0.5rem;
}

.progress-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--border);
  animation: dotPulse 1.4s ease-in-out infinite;
}

.progress-dot:nth-child(2) { animation-delay: 0.2s; }
.progress-dot:nth-child(3) { animation-delay: 0.4s; }

@keyframes dotPulse {
  0%, 80%, 100% { background: var(--border); transform: scale(1); }
  40% { background: var(--accent); transform: scale(1.4); box-shadow: 0 0 8px var(--accent-glow); }
}

/* ── Error Message ─────────────────────────────────────────── */
.error-banner {
  display: none;
  align-items: center;
  gap: 0.75rem;
  background: rgba(245,101,101,0.1);
  border: 1px solid rgba(245,101,101,0.3);
  border-radius: var(--radius-sm);
  padding: 0.9rem 1.25rem;
  color: #fc8181;
  font-size: 0.9rem;
  margin: 0 1.5rem 1.5rem;
}

.error-banner.show { display: flex; }

/* ── Features Strip ────────────────────────────────────────── */
.features {
  display: none; /* Hidden, replaced by new Why section in HTML */
}

/* ── Footer ────────────────────────────────────────────────── */
footer {
  text-align: center;
  padding: 2rem;
  color: var(--text-dim);
  font-size: 0.82rem;
  border-top: 1px solid var(--border);
}

/* ── Result / Preview Page ─────────────────────────────────── */
.result-topbar {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.9rem 1.5rem;
  background: var(--bg-topbar);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.result-filename {
  font-weight: 600;
  font-size: 0.95rem;
  flex: 1;
  min-width: 150px;
  color: var(--text);
}

.theme-badge {
  display: inline-flex;
  align-items: center;
  background: rgba(124,111,247,0.15);
  color: var(--accent2);
  border: 1px solid rgba(124,111,247,0.25);
  border-radius: 999px;
  padding: 0.2rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  white-space: nowrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent);
  color: white;
  box-shadow: 0 2px 12px rgba(124,111,247,0.35);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(124,111,247,0.5);
  color: white;
}

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

.btn-secondary:hover {
  background: var(--btn-secondary-hover);
  border-color: var(--border-hover);
  transform: translateY(-1px);
  color: var(--text);
}

/* ── Share Box (result.html) ───────────────────────────────── */
.share-box {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.share-box label {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  white-space: nowrap;
}

.share-input {
  flex: 1;
  min-width: 200px;
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.4rem 0.75rem;
  font-size: 0.82rem;
  color: var(--text-muted);
  outline: none;
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  transition: border-color var(--transition);
}

.share-input:focus {
  border-color: var(--accent);
  color: var(--text);
}

.copy-feedback {
  font-size: 0.78rem;
  color: var(--success);
  opacity: 0;
  transition: opacity 0.3s;
  font-weight: 600;
}

.copy-feedback.show { opacity: 1; }

/* ── Iframe ────────────────────────────────────────────────── */
.preview-frame {
  width: 100%;
  border: none;
  display: block;
  flex: 1;
}

.preview-wrapper {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 110px);
}

/* ── View Page ─────────────────────────────────────────────── */
.view-wrapper {
  display: flex;
  flex-direction: column;
  height: 100vh;
}

.view-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 1rem;
  background: var(--bg-topbar);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  font-size: 0.8rem;
  color: var(--text-muted);
  gap: 0.5rem;
}

.view-badge a {
  color: var(--accent2);
  font-weight: 600;
}

/* ── Responsive ────────────────────────────────────────────── */
@media (max-width: 640px) {
  .navbar { padding: 0.75rem 1.25rem; overflow: hidden; }
  .navbar .hero-badge { gap: 0.5rem; min-width: 0; flex-shrink: 1; overflow: hidden; }
  .theme-toggle-wrap { flex-shrink: 0; margin-left: 0 !important; padding-left: 0.5rem !important; }
  #conversion-count { display: none; }
  .navbar .dot { display: none; }
  #user-email { display: none !important; }
  .hero { padding: 3.5rem 1rem 2rem; }
  .result-topbar { gap: 0.5rem; }
  .result-filename { font-size: 0.85rem; }
  .theme-grid { grid-template-columns: repeat(2, 1fr); }
  .btn { padding: 0.45rem 0.75rem; font-size: 0.78rem; }
  .share-input { min-width: 120px; }
  .features { gap: 1.25rem; }
}