/* ============================================================
   AI Content Assistant — Common Styles (CSS Variables + Reset)
   Based on DESIGN_SPEC.md v1.0
   ============================================================ */

/* ----- Google Fonts ----- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

/* ----- CSS Variables (Light Mode) ----- */
:root {
  /* Brand Colors */
  --color-primary: #1E3A5F;
  --color-primary-light: #2B5A8C;
  --color-primary-dark: #14273E;

  /* Accent Colors */
  --color-accent: #10B981;
  --color-accent-light: #34D399;
  --color-accent-dark: #059669;

  /* Functional Colors */
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-error: #EF4444;
  --color-info: #3B82F6;

  /* Neutral Colors (Light) */
  --color-text-primary: #0F172A;
  --color-text-secondary: #1E293B;
  --color-text-muted: #475569;
  --color-text-light: #94A3B8;
  --color-border: #E2E8F0;
  --color-border-light: #F1F5F9;
  --color-bg: #FFFFFF;
  --color-bg-secondary: #F8FAFC;
  --color-bg-tertiary: #F1F5F9;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Monaco, 'Cascadia Code', monospace;

  /* Font Size Scale */
  --text-display: 48px;
  --text-h1: 36px;
  --text-h2: 28px;
  --text-h3: 20px;
  --text-h4: 18px;
  --text-body-large: 17px;
  --text-body: 15px;
  --text-small: 13px;
  --text-xs: 12px;

  /* Font Weights */
  --weight-bold: 700;
  --weight-semibold: 600;
  --weight-medium: 500;
  --weight-regular: 400;

  /* Line Heights */
  --leading-display: 1.1;
  --leading-h1: 1.2;
  --leading-h2: 1.25;
  --leading-body: 1.5;
  --leading-relaxed: 1.6;

  /* Spacing (4px base unit) */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.08), 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 6px rgba(15, 23, 42, 0.07), 0 2px 4px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 10px 15px rgba(15, 23, 42, 0.08), 0 4px 6px rgba(15, 23, 42, 0.04);
  --shadow-xl: 0 20px 25px rgba(15, 23, 42, 0.10), 0 8px 10px rgba(15, 23, 42, 0.06);

  /* Layout */
  --nav-height: 64px;
  --container-max: 1200px;
  --sidebar-width: 280px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;

  /* Z-index scale */
  --z-nav: 100;
  --z-overlay: 200;
  --z-modal: 300;
  --z-toast: 400;
}

/* ----- Dark Mode Variables ----- */
@media (prefers-color-scheme: dark) {
  :root {
    --color-text-primary: #F8FAFC;
    --color-text-secondary: #E2E8F0;
    --color-text-muted: #94A3B8;
    --color-text-light: #64748B;
    --color-border: #334155;
    --color-border-light: #1E293B;
    --color-bg: #0F172A;
    --color-bg-secondary: #1E293B;
    --color-bg-tertiary: #334155;

    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3), 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.35), 0 2px 4px rgba(0, 0, 0, 0.25);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4), 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.4), 0 8px 10px rgba(0, 0, 0, 0.3);
  }
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-body);
  font-weight: var(--weight-regular);
  line-height: var(--leading-body);
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
}

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

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

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

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  font-size: inherit;
}

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

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--weight-semibold);
  line-height: 1.3;
  color: var(--color-text-primary);
}

/* ----- Utility Classes ----- */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-8);
}

@media (max-width: 767px) {
  .container {
    padding: 0 var(--space-4);
  }
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ----- Page Layout ----- */
.page-wrapper {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.page-main {
  flex: 1;
  padding-top: var(--nav-height);
}

/* ----- Section Styles ----- */
.section {
  padding: var(--space-16) 0;
}

.section-title {
  font-size: var(--text-h2);
  text-align: center;
  margin-bottom: var(--space-3);
}

.section-subtitle {
  font-size: var(--text-body);
  color: var(--color-text-muted);
  text-align: center;
  max-width: 600px;
  margin: 0 auto var(--space-12);
}

/* ----- Page Header (for tool pages) ----- */
.page-header {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  color: white;
  padding: var(--space-12) 0 var(--space-10);
  text-align: center;
}

.page-header h1 {
  color: white;
  font-size: var(--text-h1);
  margin-bottom: var(--space-3);
}

.page-header p {
  color: rgba(255, 255, 255, 0.8);
  font-size: var(--text-body-large);
  max-width: 600px;
  margin: 0 auto;
}

/* ----- Loading Spinner ----- */
.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
  display: inline-block;
}

.spinner-sm {
  width: 16px;
  height: 16px;
  border-width: 2px;
}

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

/* ----- Toast ----- */
.toast-container {
  position: fixed;
  top: var(--space-6);
  right: var(--space-6);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.toast {
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-small);
  font-weight: var(--weight-medium);
  box-shadow: var(--shadow-lg);
  animation: toastIn 0.25s ease-out;
  max-width: 360px;
}

.toast-success {
  background: var(--color-accent);
  color: white;
}

.toast-error {
  background: var(--color-error);
  color: white;
}

.toast-info {
  background: var(--color-info);
  color: white;
}

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

/* ----- Focus Styles ----- */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* ----- Reduced Motion ----- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* Responsive font scaling */
@media (max-width: 767px) {
  :root {
    --text-display: 36px;
    --text-h1: 28px;
    --text-h2: 22px;
    --text-h3: 18px;
  }
}