/* =============================================================
   style.css — Global styles, custom properties, reset, typography
   Phase 2: Implement CSS custom properties and base styles
   ============================================================= */

/* --- Custom Properties (Design Tokens) --- */
:root {
  /* Colors */
  --color-primary:        #2A7B9B;
  --color-primary-dark:   #1D5C75;
  --color-accent:         #5BB5A2;
  --color-bg:             #F8FAFB;
  --color-surface:        #FFFFFF;
  --color-text:           #1A2332;
  --color-text-secondary: #5A6878;
  --color-success:        #3DAA6E;
  --color-error:          #D94F3D;
  --color-border:         #DDE4EA;

  /* Dark mode colors */
  --color-bg-dark:      #0F1A24;
  --color-surface-dark: #1A2A38;

  /* Typography */
  --font-heading: 'Playfair Display', serif;
  --font-body:    'Inter', sans-serif;
  --font-mono:    'JetBrains Mono', monospace;

  --font-xs:   0.75rem;   /*  12px */
  --font-sm:   0.875rem;  /*  14px */
  --font-base: 1rem;      /*  16px */
  --font-lg:   1.125rem;  /*  18px */
  --font-xl:   1.25rem;   /*  20px */
  --font-2xl:  1.5rem;    /*  24px */
  --font-3xl:  1.875rem;  /*  30px */
  --font-4xl:  2.25rem;   /*  36px */
  --font-5xl:  3rem;      /*  48px */

  /* Spacing (4px base unit) */
  --space-1:  0.25rem;  /*  4px */
  --space-2:  0.5rem;   /*  8px */
  --space-3:  0.75rem;  /* 12px */
  --space-4:  1rem;     /* 16px */
  --space-5:  1.25rem;  /* 20px */
  --space-6:  1.5rem;   /* 24px */
  --space-8:  2rem;     /* 32px */
  --space-10: 2.5rem;   /* 40px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  --space-20: 5rem;     /* 80px */
  --space-24: 6rem;     /* 96px */

  /* Layout */
  --max-width:    1200px;
  --nav-height:   64px;
  --border-radius: 8px;
  --border-radius-lg: 16px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0 0 0 / 0.08);
  --shadow-md: 0 4px 12px rgba(0 0 0 / 0.10);
  --shadow-lg: 0 8px 24px rgba(0 0 0 / 0.12);

  /* Transitions */
  --transition-fast:   150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow:   400ms ease;
}

/* Dark mode overrides */
[data-theme="dark"] {
  --color-bg:             #0F1A24;
  --color-surface:        #1A2A38;
  --color-text:           #E8EFF5;
  --color-text-secondary: #8FA6BB;
  --color-border:         #2A3E52;
}

/* System dark mode fallback */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-bg:             #0F1A24;
    --color-surface:        #1A2A38;
    --color-text:           #E8EFF5;
    --color-text-secondary: #8FA6BB;
    --color-border:         #2A3E52;
  }
}

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

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

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  font-family: var(--font-body);
  font-size: var(--font-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

ul,
ol {
  list-style: none;
}

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

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

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: 2px;
}

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

/* --- Skip link --- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--border-radius);
  font-weight: 600;
  z-index: 9999;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-4);
}

/* --- Container --- */
.container {
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: var(--space-6);
}

@media (max-width: 640px) {
  .container {
    padding-inline: var(--space-4);
  }
}

/* --- Sections --- */
.section {
  padding-block: var(--space-20);
}

.section__heading {
  font-family: var(--font-heading);
  font-size: var(--font-3xl);
  color: var(--color-text);
  margin-bottom: var(--space-10);
  position: relative;
}

.section__heading::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background-color: var(--color-primary);
  margin-top: var(--space-3);
  border-radius: 2px;
}

.section__intro {
  color: var(--color-text-secondary);
  font-size: var(--font-lg);
  margin-bottom: var(--space-8);
  max-width: 65ch;
}

.subsection__heading {
  font-family: var(--font-heading);
  font-size: var(--font-xl);
  color: var(--color-text);
  margin-bottom: var(--space-6);
  margin-top: var(--space-10);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-base);
  font-weight: 600;
  border-radius: var(--border-radius);
  transition: background-color var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
  text-decoration: none;
  cursor: pointer;
}

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

.btn--primary:hover {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #fff;
  text-decoration: none;
}

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

.btn--outline:hover {
  background-color: var(--color-primary);
  color: #fff;
  text-decoration: none;
}

.btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  color: var(--color-text);
  transition: background-color var(--transition-fast);
}

.btn-icon:hover {
  background-color: var(--color-border);
}

/* --- Badges --- */
.upcoming-badge {
  display: inline-block;
  background-color: var(--color-accent);
  color: #fff;
  font-size: var(--font-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: var(--space-1) var(--space-2);
  border-radius: 4px;
  margin-bottom: var(--space-2);
}

.setting-badge {
  display: inline-block;
  background-color: color-mix(in srgb, var(--color-primary) 12%, transparent);
  color: var(--color-primary-dark);
  font-size: var(--font-xs);
  font-weight: 600;
  padding: var(--space-1) var(--space-2);
  border-radius: 4px;
}

/* --- Scroll-reveal animation --- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Placeholder text --- */
.placeholder-text {
  color: var(--color-text-secondary);
  font-style: italic;
}

/* --- Date range --- */
.date-range {
  color: var(--color-text-secondary);
  font-size: var(--font-sm);
}