:root {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #1e293b;
  --bg-card-hover: #263548;
  --bg-input: #0f172a;
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-glow: rgba(59, 130, 246, 0.15);
  --border: #334155;
  --success: #22c55e;
  --warning: #f59e0b;
  --error: #ef4444;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0,0,0,0.3);
  --transition: 0.25s ease;
}

[data-theme="light"] {
  --bg-primary: #eff6ff;
  --bg-secondary: #dbeafe;
  --bg-card: #ffffff;
  --bg-card-hover: #f0f7ff;
  --bg-input: #f8fafc;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-glow: rgba(37, 99, 235, 0.1);
  --border: #bfdbfe;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); }

/* Header */
.header {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  transition: background var(--transition), border-color var(--transition);
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.logo svg { width: 32px; height: 32px; }

.header-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle {
  background: var(--bg-input);
  border: 1px solid var(--border);
  color: var(--text-primary);
  width: 42px;
  height: 42px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  transition: all var(--transition);
}

.theme-toggle:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.back-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  transition: all var(--transition);
}

.back-link:hover {
  color: var(--accent);
  background: var(--accent-glow);
}

/* Hero */
.hero {
  text-align: center;
  padding: 3rem 2rem 1.5rem;
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  color: var(--text-secondary);
  font-size: 1.15rem;
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.6;
}

/* Section */
.section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem 2rem 3rem;
}

.section-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 1.25rem;
  padding-left: 0.25rem;
}

/* Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
}

/* Tile */
.tile {
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  color: inherit;
}

.tile:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent), var(--shadow);
  transform: translateY(-2px);
  color: inherit;
}

.tile-icon {
  width: 48px;
  height: 48px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 1rem;
  background: var(--accent-glow);
  color: var(--accent);
}

.tile-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.35rem;
}

.tile-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.tile-badge {
  display: inline-block;
  margin-top: 0.75rem;
  padding: 0.2rem 0.6rem;
  border-radius: 20px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: var(--accent-glow);
  color: var(--accent);
  width: fit-content;
}

/* Tool page layout */
.tool-container {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem;
}

.tool-header {
  margin-bottom: 2rem;
}

.tool-header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.tool-header p {
  color: var(--text-secondary);
  line-height: 1.5;
}

.tool-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.25rem;
  transition: background var(--transition), border-color var(--transition);
}

.tool-card h2 {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 1rem;
}

/* Form elements */
textarea, input[type="text"], input[type="number"], select {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text-primary);
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.9rem;
  resize: vertical;
  transition: border-color var(--transition), background var(--transition);
}

textarea:focus, input:focus, select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

textarea { min-height: 120px; }

label {
  display: block;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.25rem;
  border: none;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover { background: var(--accent-hover); }

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

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent);
}

.btn-group {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

.output-area {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem 1rem;
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.9rem;
  color: var(--text-primary);
  min-height: 80px;
  word-break: break-all;
  white-space: pre-wrap;
  transition: background var(--transition), border-color var(--transition);
}

.status-msg {
  margin-top: 0.75rem;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  font-size: 0.85rem;
  display: none;
}

.status-msg.success { display: block; background: rgba(34,197,94,0.1); color: var(--success); }
.status-msg.error { display: block; background: rgba(239,68,68,0.1); color: var(--error); }

/* Tabs */
.tabs {
  display: flex;
  gap: 0.25rem;
  margin-bottom: 1.25rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0;
}

.tab {
  padding: 0.6rem 1.25rem;
  border: none;
  background: none;
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all var(--transition);
  font-family: inherit;
  margin-bottom: -1px;
}

.tab:hover { color: var(--text-primary); }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); }

.tab-content { display: none; }
.tab-content.active { display: block; }

/* Checkbox/option pills */
.option-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0.5rem 0;
}

.option-pill {
  padding: 0.4rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--bg-input);
  color: var(--text-secondary);
  font-family: inherit;
}

.option-pill:hover, .option-pill.active {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-glow);
}

/* Copy button */
.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.3rem 0.6rem;
  font-size: 0.75rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.copy-btn:hover { border-color: var(--accent); color: var(--accent); }

.output-wrapper { position: relative; }

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

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.75rem; }
  .hero p { font-size: 1rem; }
  .grid { grid-template-columns: 1fr; }
  .header { padding: 0.75rem 1rem; }
  .section { padding: 1rem; }
  .tool-container { padding: 1rem; }
}