/* ========================================
   CSS Variables & Theme System
   ======================================== */
:root {
  /* Light Theme Colors */
  --bg-primary: #fafafa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f4f4f5;
  --text-primary: #18181b;
  --text-secondary: #52525b;
  --text-muted: #71717a;
  --border-color: #e4e4e7;
  --border-hover: #d4d4d8;
  
  /* Accent Colors */
  --accent-blue: #3b82f6;
  --accent-emerald: #10b981;
  --accent-orange: #f97316;
  --accent-rose: #f43f5e;
  --accent-violet: #8b5cf6;
  --accent-slate: #475569;
  
  /* Active Theme Color (default: blue) */
  --accent-color: var(--accent-blue);
  --accent-hover: #2563eb;
  --accent-light: rgba(59, 130, 246, 0.1);
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  
  /* Spacing & Sizing */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-primary: #0a0a0b;
  --bg-secondary: #18181b;
  --bg-tertiary: #27272a;
  --text-primary: #fafafa;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --border-color: #27272a;
  --border-hover: #3f3f46;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
}

/* Accent Color Variations */
[data-accent="blue"] {
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --accent-light: rgba(59, 130, 246, 0.1);
}

[data-accent="emerald"] {
  --accent-color: #10b981;
  --accent-hover: #059669;
  --accent-light: rgba(16, 185, 129, 0.1);
}

[data-accent="orange"] {
  --accent-color: #f97316;
  --accent-hover: #ea580c;
  --accent-light: rgba(249, 115, 22, 0.1);
}

[data-accent="rose"] {
  --accent-color: #f43f5e;
  --accent-hover: #e11d48;
  --accent-light: rgba(244, 63, 94, 0.1);
}

[data-accent="violet"] {
  --accent-color: #8b5cf6;
  --accent-hover: #7c3aed;
  --accent-light: rgba(139, 92, 246, 0.1);
}

[data-accent="slate"] {
  --accent-color: #475569;
  --accent-hover: #334155;
  --accent-light: rgba(71, 85, 105, 0.1);
}

/* ========================================
   Base Styles
   ======================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--transition-base), color var(--transition-base);
}

/* ========================================
   Navigation
   ======================================== */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--accent-color);
  color: #ffffff;
  box-shadow: var(--shadow-md);
  transition: background-color var(--transition-base);
}

.nav-container {
  max-width: 80rem;
  margin: 0 auto;
  padding: 0 1rem;
  height: 4rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: inherit;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.25rem;
}

.nav-icon {
  width: 1.5rem;
  height: 1.5rem;
}

.nav-links {
  display: none;
  align-items: center;
  gap: 0.5rem;
}

.nav-link {
  color: rgba(255, 255, 255, 0.85);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.nav-link:hover {
  color: #ffffff;
  background-color: rgba(255, 255, 255, 0.15);
}

.nav-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.control-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background: rgba(255, 255, 255, 0.1);
  border: none;
  border-radius: var(--radius-md);
  color: #ffffff;
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.control-btn:hover {
  background: rgba(255, 255, 255, 0.2);
}

.control-btn svg {
  width: 1.25rem;
  height: 1.25rem;
}

/* Dropdown */
.dropdown {
  position: relative;
}

.dropdown-menu {
  position: absolute;
  top: calc(100% + 0.5rem);
  right: 0;
  min-width: 10rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 0.5rem;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-0.5rem);
  transition: all var(--transition-fast);
}

.dropdown-menu.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.color-option {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  width: 100%;
  padding: 0.5rem 0.75rem;
  background: none;
  border: none;
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.875rem;
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.color-option:hover {
  background: var(--bg-tertiary);
}

.color-option.active {
  background: var(--accent-light);
}

.color-swatch {
  width: 1rem;
  height: 1rem;
  border-radius: 50%;
}

.color-swatch.blue { background: #3b82f6; }
.color-swatch.emerald { background: #10b981; }
.color-swatch.orange { background: #f97316; }
.color-swatch.rose { background: #f43f5e; }
.color-swatch.violet { background: #8b5cf6; }
.color-swatch.slate { background: #475569; }

/* Mobile Menu */
.mobile-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background: none;
  border: none;
  color: #ffffff;
  cursor: pointer;
}

.mobile-menu-btn svg {
  width: 1.5rem;
  height: 1.5rem;
}

.mobile-menu {
  padding: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.mobile-link {
  display: block;
  padding: 0.75rem 1rem;
  color: rgba(255, 255, 255, 0.9);
  text-decoration: none;
  border-radius: var(--radius-md);
  font-weight: 500;
  transition: background-color var(--transition-fast);
}

.mobile-link:hover {
  background: rgba(255, 255, 255, 0.1);
}

.hidden {
  display: none !important;
}

/* Theme Toggle Icons */
.sun-icon, .moon-icon {
  transition: transform var(--transition-fast);
}

[data-theme="dark"] .sun-icon {
  display: none;
}

[data-theme="dark"] .moon-icon {
  display: block !important;
}

[data-theme="light"] .moon-icon {
  display: none;
}

/* ========================================
   Main Content
   ======================================== */
.main-content {
  max-width: 80rem;
  margin: 0 auto;
  padding: 2rem 1rem;
}

/* Hero Section */
.hero {
  text-align: center;
  margin-bottom: 3rem;
}

.hero h1 {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 1rem;
  text-wrap: balance;
}

.hero p {
  max-width: 40rem;
  margin: 0 auto;
  color: var(--text-secondary);
  font-size: 1.125rem;
  text-wrap: pretty;
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-bottom: 3rem;
}

.stat-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  transition: box-shadow var(--transition-base), border-color var(--transition-base);
}

.stat-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--border-hover);
}

.stat-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  border-radius: var(--radius-lg);
  flex-shrink: 0;
}

.stat-icon svg {
  width: 1.5rem;
  height: 1.5rem;
}

.stat-icon.blue-bg {
  background: rgba(59, 130, 246, 0.1);
  color: #3b82f6;
}

.stat-icon.emerald-bg {
  background: rgba(16, 185, 129, 0.1);
  color: #10b981;
}

.stat-icon.orange-bg {
  background: rgba(249, 115, 22, 0.1);
  color: #f97316;
}

.stat-info {
  display: flex;
  flex-direction: column;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  line-height: 1.2;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Forms Grid */
.forms-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

.forms-column {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* Card */
.card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  overflow: hidden;
  transition: border-color var(--transition-base);
}

.card-header {
  padding: 1.5rem 1.5rem 0;
}

.card-header h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.card-header p {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.card-body {
  padding: 1.5rem;
}

/* Form Elements */
.form-group {
  margin-bottom: 1.25rem;
}

.form-group:last-of-type {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

input[type="text"],
input[type="number"],
input[type="date"],
select,
textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.9375rem;
  font-family: inherit;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

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

input::placeholder,
textarea::placeholder {
  color: var(--text-muted);
}

textarea {
  resize: vertical;
  min-height: 5rem;
}

select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2371717a' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  padding-right: 2.5rem;
}

/* Color Picker */
.color-picker {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.color-btn {
  width: 2.25rem;
  height: 2.25rem;
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.color-btn:hover {
  transform: scale(1.1);
}

.color-btn.selected {
  border-color: var(--text-primary);
  box-shadow: 0 0 0 2px var(--bg-secondary);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-size: 0.9375rem;
  font-weight: 600;
  font-family: inherit;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-primary {
  width: 100%;
  background: var(--accent-color);
  color: #ffffff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-primary:active {
  transform: translateY(0);
}

/* ========================================
   Footer
   ======================================== */
.footer {
  margin-top: 4rem;
  padding: 2rem 1rem;
  border-top: 1px solid var(--border-color);
  text-align: center;
}

.footer p {
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* ========================================
   Responsive Design
   ======================================== */
@media (min-width: 640px) {
  .nav-container {
    padding: 0 1.5rem;
  }
  
  .form-row {
    grid-template-columns: 1fr 1fr;
  }
  
  .stats-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  
  .hero h1 {
    font-size: 3rem;
  }
  
  .main-content {
    padding: 3rem 1.5rem;
  }
}

@media (min-width: 768px) {
  .mobile-menu-btn {
    display: none;
  }
  
  .nav-links {
    display: flex;
  }
  
  .mobile-menu {
    display: none !important;
  }
}

@media (min-width: 1024px) {
  .forms-grid {
    grid-template-columns: 1fr 1fr;
  }
  
  .nav-container {
    padding: 0 2rem;
  }
  
  .main-content {
    padding: 3rem 2rem;
  }
}