/* ========================================
   Базові стилі
   ======================================== */

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

:root {
  /* Кольори */
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-success: #16a34a;
  --color-success-light: #dcfce7;
  --color-error: #dc2626;
  --color-error-light: #fee2e2;
  --color-text: #1f2937;
  --color-text-secondary: #6b7280;
  --color-text-muted: #9ca3af;
  --color-border: #e5e7eb;
  --color-border-focus: #2563eb;
  --color-bg: #f9fafb;
  --color-bg-card: #ffffff;
  --color-disabled: #f3f4f6;
  
  /* Тіні */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  
  /* Радіуси */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  /* Переходи */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  
  /* Розміри */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-md);
}

/* ========================================
   Контейнер та картка
   ======================================== */

.container {
  width: 100%;
  max-width: 480px;
}

.card {
  background: var(--color-bg-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: var(--spacing-xl);
}

.error-card {
  text-align: center;
  padding: var(--spacing-xl) var(--spacing-lg);
}

.card-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--spacing-lg);
  text-align: center;
}

/* ========================================
   Форма
   ======================================== */

.form {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.form-label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
}

.required {
  color: var(--color-error);
  margin-left: 2px;
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 1rem;
  font-family: inherit;
  color: var(--color-text);
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

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

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

.form-input:disabled,
.form-select:disabled,
.form-textarea:disabled {
  background-color: var(--color-disabled);
  color: var(--color-text-muted);
  cursor: not-allowed;
}

.form-textarea {
  min-height: 100px;
  resize: vertical;
}

.form-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='%236b7280' 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 var(--spacing-md) center;
  padding-right: 40px;
}

.form-select:disabled {
  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='%239ca3af' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3C/polyline%3E%3C/svg%3E");
}

/* File input */
.form-input[type="file"] {
  padding: var(--spacing-xs) var(--spacing-sm);
  background-color: var(--color-bg);
}

.form-input[type="file"]::file-selector-button {
  padding: var(--spacing-xs) var(--spacing-md);
  font-size: 0.875rem;
  font-weight: 500;
  font-family: inherit;
  color: white;
  background-color: var(--color-primary);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background-color var(--transition-fast);
  margin-right: var(--spacing-md);
}

.form-input[type="file"]::file-selector-button:hover {
  background-color: var(--color-primary-hover);
}

.form-hint {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  margin-top: var(--spacing-xs);
}

.error-message {
  font-size: 0.75rem;
  color: var(--color-error);
  min-height: 1rem;
  display: none;
}

.error-message.visible {
  display: block;
}

.form-input.error,
.form-select.error,
.form-textarea.error {
  border-color: var(--color-error);
}

.form-input.error:focus,
.form-select.error:focus,
.form-textarea.error:focus {
  box-shadow: 0 0 0 3px var(--color-error-light);
}

/* ========================================
   Кнопки
   ======================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: 1rem;
  font-weight: 500;
  font-family: inherit;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

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

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

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-primary-hover);
}

.btn-primary:active:not(:disabled) {
  transform: scale(0.98);
}

.btn-secondary {
  background-color: var(--color-text-secondary);
  color: white;
  width: 100%;
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-text);
}

.btn-secondary:active:not(:disabled) {
  transform: scale(0.98);
}

.btn-success {
  background-color: var(--color-success);
  color: white;
  width: 100%;
}

.btn-success:hover:not(:disabled) {
  background-color: #15803d;
}

.btn-success:active:not(:disabled) {
  transform: scale(0.98);
}

.btn-loader {
  width: 20px;
  height: 20px;
  border: 2px solid transparent;
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* ========================================
   Повідомлення
   ======================================== */

.message {
  margin-top: var(--spacing-md);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  text-align: center;
  animation: slideIn 0.3s ease;
}

.message.success {
  background-color: var(--color-success-light);
  color: var(--color-success);
  border: 1px solid #bbf7d0;
}

.message.error {
  background-color: var(--color-error-light);
  color: var(--color-error);
  border: 1px solid #fecaca;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ========================================
   Сторінки помилок
   ======================================== */

.error-code {
  font-size: 4rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
  margin-bottom: var(--spacing-sm);
}

.error-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--spacing-sm);
}

.error-message {
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-lg);
}

.error-details {
  background: var(--color-disabled);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  font-size: 0.75rem;
  text-align: left;
  overflow-x: auto;
  margin-bottom: var(--spacing-lg);
  color: var(--color-text-secondary);
}

/* ========================================
   Навігація (вкладки)
   ======================================== */

.nav-tabs {
  display: flex;
  gap: var(--spacing-xs);
  margin-bottom: var(--spacing-lg);
  border-bottom: 2px solid var(--color-border);
  padding-bottom: var(--spacing-xs);
}

.nav-tab {
  flex: 1;
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 0.875rem;
  font-weight: 500;
  font-family: inherit;
  color: var(--color-text-secondary);
  background: transparent;
  border: none;
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  cursor: pointer;
  transition: color var(--transition-fast), background-color var(--transition-fast);
  text-decoration: none;
  text-align: center;
}

.nav-tab:hover:not(.active) {
  color: var(--color-text);
  background-color: var(--color-bg);
}

.nav-tab.active {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  border-bottom: 2px solid var(--color-primary);
  margin-bottom: -2px;
}

.nav-tab:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

/* ========================================
   Адаптивність
   ======================================== */

@media (max-width: 480px) {
  .card {
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
  }
  
  .card-title {
    font-size: 1.25rem;
  }
  
  .error-code {
    font-size: 3rem;
  }
  
  .nav-tab {
    padding: var(--spacing-sm) var(--spacing-sm);
    font-size: 0.8125rem;
  }
}