/* ===================================
   Coloring Book App - Global Styles
   =================================== */

/* CSS Variables for consistent theming */
:root {
  --primary-color: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --secondary-color: #ec4899;
  --success-color: #10b981;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-light: #9ca3af;
  
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --bg-dark: #111827;
  
  --border-color: #e5e7eb;
  --border-radius: 12px;
  --border-radius-lg: 16px;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  
  --transition: all 0.3s ease;
}

/* Reset & Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-secondary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.875rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

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

a:hover {
  color: var(--primary-dark);
}

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.75rem;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--primary-color);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background: white;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
  background: var(--primary-color);
  color: white;
}

.btn-large {
  padding: 1.125rem 2.5rem;
  font-size: 1.125rem;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none !important;
}

/* Header/Navigation */
header {
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary-color);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo:hover {
  color: var(--primary-dark);
}

/* Hero Section */
.hero {
  padding: 5rem 0;
  text-align: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
}

.hero h1 {
  color: white;
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
}

.hero p {
  color: rgba(255, 255, 255, 0.9);
  font-size: 1.25rem;
  max-width: 600px;
  margin: 0 auto 2rem;
}

/* Sections */
section {
  padding: 4rem 0;
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
}

/* Feature Cards */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.feature-card {
  background: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  text-align: center;
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-xl);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.feature-card h3 {
  color: var(--primary-color);
  margin-bottom: 1rem;
}

/* Upload Area */
.upload-area {
  border: 3px dashed var(--border-color);
  border-radius: var(--border-radius-lg);
  padding: 3rem 2rem;
  text-align: center;
  background: var(--bg-primary);
  cursor: pointer;
  transition: var(--transition);
}

.upload-area:hover,
.upload-area.dragover {
  border-color: var(--primary-color);
  background: rgba(99, 102, 241, 0.05);
}

.upload-icon {
  font-size: 4rem;
  color: var(--text-light);
  margin-bottom: 1rem;
}

.upload-area input[type="file"] {
  display: none;
}

/* Image Preview */
.image-preview {
  margin: 2rem 0;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.image-preview img {
  width: 100%;
  max-height: 500px;
  object-fit: contain;
  display: block;
}

/* Loading Spinner */
.loader {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 0.8s linear infinite;
}

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

.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.85);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  backdrop-filter: blur(4px);
}

.loading-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  max-width: 500px;
  width: 90%;
}

.loading-spinner {
  width: 60px;
  height: 60px;
  border: 6px solid rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  border-top-color: var(--primary-light);
  border-right-color: var(--primary-color);
  animation: spin 1s cubic-bezier(0.68, -0.55, 0.265, 1.55) infinite;
}

.loading-text {
  color: white;
  font-size: 1.25rem;
  margin-top: 1.5rem;
  text-align: center;
  width: 100%;
}

.loading-tip {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9rem;
  margin-top: 0.75rem;
  text-align: center;
}

/* Progress Bar */
.progress-container {
  width: 100%;
  margin-top: 1.5rem;
  position: relative;
}

.progress-bar {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 10px;
  overflow: hidden;
  position: relative;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.progress-bar-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--primary-color), var(--primary-light), var(--secondary-color));
  background-size: 200% 100%;
  border-radius: 10px;
  transition: width 0.3s ease-out;
  animation: progressGradient 2s ease infinite;
  box-shadow: 0 0 10px rgba(99, 102, 241, 0.5);
}

@keyframes progressGradient {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}

.progress-text {
  color: white;
  font-size: 0.875rem;
  font-weight: 600;
  margin-top: 0.5rem;
  text-align: center;
  letter-spacing: 0.5px;
}

/* Modal */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10000;
  padding: 1rem;
}

.modal {
  background: var(--bg-primary);
  border-radius: var(--border-radius-lg);
  padding: 2.5rem;
  max-width: 450px;
  width: 100%;
  box-shadow: var(--shadow-xl);
  animation: modalSlideIn 0.3s ease-out;
}

@keyframes modalSlideIn {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.modal h2 {
  margin-bottom: 1.5rem;
  color: var(--primary-color);
}

/* Forms */
.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
  color: var(--text-primary);
}

.form-input {
  width: 100%;
  padding: 0.875rem 1rem;
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  font-size: 1rem;
  transition: var(--transition);
}

.form-input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Alerts */
.alert {
  padding: 1rem 1.25rem;
  border-radius: var(--border-radius);
  margin-bottom: 1rem;
  font-weight: 500;
}

.alert-success {
  background: #d1fae5;
  color: #065f46;
  border-left: 4px solid var(--success-color);
}

.alert-error {
  background: #fee2e2;
  color: #991b1b;
  border-left: 4px solid var(--danger-color);
}

.alert-info {
  background: #dbeafe;
  color: #1e40af;
  border-left: 4px solid var(--primary-color);
}

/* Footer */
footer {
  background: var(--bg-dark);
  color: white;
  padding: 2rem 0;
  text-align: center;
  margin-top: 4rem;
}

footer p {
  color: rgba(255, 255, 255, 0.7);
  margin: 0;
}

/* Utilities */
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.hidden { display: none !important; }

/* Responsive Design */
@media (max-width: 768px) {
  h1 { font-size: 2.25rem; }
  h2 { font-size: 1.875rem; }
  h3 { font-size: 1.5rem; }
  
  .hero h1 {
    font-size: 2.5rem;
  }
  
  .hero p {
    font-size: 1.125rem;
  }
  
  section {
    padding: 3rem 0;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
  
  .btn-large {
    padding: 1rem 2rem;
    font-size: 1rem;
  }
  
  .modal {
    padding: 2rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 1rem;
  }
  
  .hero {
    padding: 3rem 0;
  }
  
  .upload-area {
    padding: 2rem 1rem;
  }
}