/* ===== Variables & Reset ===== */
:root {
  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  
  /* Colors */
  --color-primary: #0066cc;
  --color-primary-dark: #0052a3;
  --color-primary-light: #e6f2ff;
  --color-danger: #dc3545;
  --color-danger-light: #f8d7da;
  --color-success: #28a745;
  --color-success-light: #d4edda;
  --color-gray-100: #f8f9fa;
  --color-gray-200: #e9ecef;
  --color-gray-300: #dee2e6;
  --color-gray-500: #adb5bd;
  --color-gray-600: #6c757d;
  --color-gray-700: #495057;
  --color-gray-800: #343a40;
  
  /* Typography */
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 20px;
  --font-size-2xl: 24px;
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  
  /* Transitions */
  --transition-base: 250ms ease;
}

/* ===== Sections ===== */
.form-section {
  border: 1px solid var(--color-gray-300);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  margin-bottom: var(--space-xl);
  background: white;
  position: relative;
}

.section-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-gray-800);
  margin-bottom: var(--space-lg);
  padding: 0;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.section-number {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: var(--color-primary);
  color: white;
  border-radius: 50%;
  font-size: var(--font-size-sm);
  font-weight: 600;
  flex-shrink: 0;
}

/* ===== Form Grid ===== */
.form-row {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

/* ===== Form Groups ===== */
.form-group {
  margin-bottom: var(--space-lg);
  position: relative;
}

.form-group-half {
  flex: 1;
}

.form-label {
  display: block;
  margin-bottom: var(--space-sm);
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--color-gray-800);
  line-height: 1.4;
}

/* ===== Inputs ===== */
.form-input,
.form-select {
  width: 100%;
  padding: var(--space-md);
  font-size: var(--font-size-base);
  line-height: 1.5;
  color: var(--color-gray-800);
  background-color: white;
  border: 2px solid var(--color-gray-300);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
  appearance: none;
  min-height: 52px;
}

.form-input:hover,
.form-select:hover {
  border-color: var(--color-gray-500);
}

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

.form-input.is-invalid {
  border-color: var(--color-danger);
  background-color: var(--color-danger-light);
}

.form-input.is-valid {
  border-color: var(--color-success);
}

/* Select specific styles */
.form-select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='%23495057' viewBox='0 0 16 16'%3E%3Cpath d='M7.247 11.14 2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right var(--space-md) center;
  background-size: 16px 12px;
  padding-right: calc(var(--space-md) * 2 + 16px);
}

/* ===== Error Messages ===== */
.error-message {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-top: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background-color: var(--color-danger-light);
  border: 1px solid var(--color-danger);
  border-radius: var(--radius-sm);
  color: var(--color-danger);
  font-size: var(--font-size-sm);
  animation: slideDown var(--transition-base);
}

.error-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  background: var(--color-danger);
  color: white;
  border-radius: 50%;
  font-size: var(--font-size-xs);
  font-weight: bold;
  flex-shrink: 0;
}

.input-hint {
  margin-top: var(--space-xs);
  color: var(--color-gray-600);
  font-size: var(--font-size-sm);
  line-height: 1.4;
}

/* ===== Global Alert ===== */
.alert {
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-lg);
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  animation: slideDown var(--transition-base);
}

.alert-error {
  background-color: var(--color-danger-light);
  border: 1px solid var(--color-danger);
  color: var(--color-danger);
}

.alert-icon {
  flex-shrink: 0;
  line-height: 1;
  font-size: var(--font-size-lg);
}

/* ===== Form Actions ===== */
.form-actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-gray-300);
}

.btn-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  min-height: 56px;
  padding: var(--space-md) var(--space-xl);
  font-size: var(--font-size-base);
  font-weight: 500;
  text-decoration: none;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  flex: 1;
}

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

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

.btn-secondary {
  background-color: white;
  color: var(--color-gray-800);
  border: 2px solid var(--color-gray-300);
}

.btn-secondary:hover {
  background-color: var(--color-gray-100);
  border-color: var(--color-gray-500);
  transform: translateY(-2px);
}

.btn-icon {
  font-size: var(--font-size-lg);
  line-height: 1;
}

.btn-text {
  flex: 1;
}

/* ===== Loading Overlay ===== */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(255, 255, 255, 0.9);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  z-index: 1000;
  opacity: 0;
  transition: opacity var(--transition-base);
}

.loading-overlay.active {
  display: flex;
  animation: fadeIn var(--transition-base) forwards;
}

.loading-spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--color-gray-300);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

/* ===== Form Note ===== */
.form-note {
  margin-top: var(--space-lg);
  padding: var(--space-md);
  background-color: var(--color-gray-100);
  border-radius: var(--radius-md);
  color: var(--color-gray-600);
  font-size: var(--font-size-sm);
  text-align: center;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
}

.lock-icon {
  font-size: var(--font-size-base);
}

/* ===== Animations ===== */
@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

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

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
  20%, 40%, 60%, 80% { transform: translateX(5px); }
}

/* ===== Responsive Breakpoints ===== */

/* Mobile (≥ 480px) */
@media (min-width: 480px) {
  .shipping-form {
    padding: var(--space-md);
  }
  
  .form-actions {
    flex-direction: row;
  }
  
  .btn-action {
    min-height: 52px;
  }
}

/* Tablet (≥ 768px) */
@media (min-width: 768px) {
  .shipping-form {
    max-width: 720px;
    padding: var(--space-xl);
  }
  
  .form-row {
    flex-direction: row;
    gap: var(--space-lg);
  }
  
  .form-section {
    padding: var(--space-xl);
  }
  
  .section-title {
    font-size: var(--font-size-xl);
  }
  
  .btn-action {
    min-height: 48px;
    padding: var(--space-md) var(--space-2xl);
  }
}

/* Desktop (≥ 1200px) */
@media (min-width: 1200px) {
  .shipping-form {
    max-width: 800px;
  }
  
  .form-section {
    padding: var(--space-2xl);
  }
}