/* ==========================================================================
   ONLINE FILE & IMAGE CONVERTER - Modern Design System
   Aesthetic: Dark Slate/Indigo Glassmorphism, Vibrant Accents, High Contrast
   ========================================================================== */

:root {
  /* Color Palette - Dark Mode Default */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-glass: rgba(30, 41, 59, 0.75);
  --bg-glass-hover: rgba(51, 65, 85, 0.85);

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

  --accent-primary: #6366f1;
  --accent-primary-hover: #4f46e5;
  --accent-secondary: #06b6d4;
  --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #06b6d4 100%);
  --accent-gradient-hover: linear-gradient(135deg, #4f46e5 0%, #9333ea 50%, #0891b2 100%);

  --success: #10b981;
  --success-bg: rgba(16, 185, 129, 0.15);
  --warning: #f59e0b;
  --warning-bg: rgba(245, 158, 11, 0.15);
  --danger: #ef4444;
  --danger-bg: rgba(239, 68, 68, 0.15);

  --border-color: rgba(255, 255, 255, 0.1);
  --border-hover: rgba(99, 102, 241, 0.4);

  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 12px 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, 0.3);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme Overrides */
[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-glass: rgba(255, 255, 255, 0.85);
  --bg-glass-hover: rgba(241, 245, 249, 0.95);

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

  --border-color: rgba(0, 0, 0, 0.08);
  --border-hover: rgba(99, 102, 241, 0.5);

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.2);
}

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

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--accent-secondary);
}

img, svg {
  max-width: 100%;
  height: auto;
  display: block;
}

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

/* Layout Containers */
.container {
  width: 100%;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

.main-content {
  flex: 1;
  padding-bottom: 4rem;
}

/* Header & Navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  padding: 0.85rem 0;
  transition: background-color var(--transition-normal);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
}

.site-logo svg {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
}

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

.nav-menu {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
}

.nav-link {
  font-weight: 500;
  color: var(--text-secondary);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.nav-link:hover, .nav-link.active {
  color: var(--text-primary);
  background-color: var(--bg-tertiary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.theme-toggle-btn {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.theme-toggle-btn:hover {
  background: var(--border-hover);
  transform: rotate(15deg);
}

.mobile-menu-toggle {
  display: none;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

/* Privacy Guarantee Banner */
.privacy-banner {
  background: rgba(99, 102, 241, 0.1);
  border: 1px solid rgba(99, 102, 241, 0.2);
  border-radius: var(--radius-md);
  padding: 0.85rem 1.25rem;
  margin: 1.5rem 0;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-primary);
  font-size: 0.95rem;
}

.privacy-banner-icon {
  color: var(--accent-secondary);
  flex-shrink: 0;
}

/* Hero Section */
.hero-section {
  text-align: center;
  padding: 3rem 0 2rem;
}

.hero-title {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.hero-title .gradient-text {
  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;
}

/* Tool Grid Section */
.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-bottom: 3rem;
}

.tool-card {
  background: var(--bg-glass);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  text-decoration: none;
  color: inherit;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.tool-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

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

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

.tool-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: rgba(99, 102, 241, 0.15);
  color: var(--accent-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.tool-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-primary);
}

.tool-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.tool-badge {
  align-self: flex-start;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-full);
  background: rgba(6, 182, 212, 0.15);
  color: var(--accent-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Category Filter Tabs */
.category-tabs {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.category-tab {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-full);
  font-weight: 500;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.category-tab:hover, .category-tab.active {
  background: var(--accent-primary);
  color: #ffffff;
  border-color: var(--accent-primary);
}

/* Footer */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 2rem;
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-brand p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: 0.75rem;
  max-width: 320px;
}

.footer-heading {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--text-muted);
  font-size: 0.85rem;
  flex-wrap: wrap;
  gap: 1rem;
}

/* Responsive Styles */
@media (max-width: 900px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .hero-title {
    font-size: 2rem;
  }
  .hero-subtitle {
    font-size: 1rem;
  }
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    flex-direction: column;
    padding: 1rem;
    gap: 0.5rem;
  }
  .nav-menu.active {
    display: flex;
  }
  .mobile-menu-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
}