/* ------------------------------------------------------------------
 * theme.css — Apple-inspired design tokens + base typography
 * Palette and type scale derived from Apple's public marketing system
 * (SF Pro Display/Text sizes, weights, tracking, and line-heights).
 * ------------------------------------------------------------------ */

/* ---------- Inter (SF Pro substitute) ---------- */
@font-face {
  font-family: 'Inter';
  font-weight: 300;
  font-style: normal;
  font-display: swap;
  src: url('/font/inter/Inter-Light.woff2') format('woff2');
}
@font-face {
  font-family: 'Inter';
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  src: url('/font/inter/Inter-Regular.woff2') format('woff2');
}
@font-face {
  font-family: 'Inter';
  font-weight: 600;
  font-style: normal;
  font-display: swap;
  src: url('/font/inter/Inter-SemiBold.woff2') format('woff2');
}
@font-face {
  font-family: 'Inter';
  font-weight: 700;
  font-style: normal;
  font-display: swap;
  src: url('/font/inter/Inter-Bold.woff2') format('woff2');
}

/* ---------- Design tokens ---------- */
:root {
  /* Surfaces */
  --sk-bg-light: #f5f5f7;
  --sk-bg-dark: #000000;
  --sk-page-bg: var(--sk-bg-light);
  --sk-surface: #ffffff;
  --sk-surface-muted: #ebebef;
  --sk-surface-dark-1: #272729;
  --sk-surface-dark-2: #2a2a2d;

  /* Text */
  --sk-text-primary: #1d1d1f;
  --sk-text-body: rgba(0, 0, 0, 0.8);
  --sk-text-tertiary: rgba(0, 0, 0, 0.48);
  --sk-text-inverse: #ffffff;
  --sk-text-inverse-body: rgba(255, 255, 255, 0.88);
  --sk-text-inverse-tertiary: rgba(255, 255, 255, 0.56);

  /* Interactive */
  --sk-accent: #0071e3;
  --sk-link: #0066cc;
  --sk-link-dark-bg: #2997ff;
  --sk-focus: #0071e3;

  /* Rules + shadows */
  --sk-rule: rgba(0, 0, 0, 0.08);
  --sk-rule-inverse: rgba(255, 255, 255, 0.12);
  --sk-card-shadow: rgba(0, 0, 0, 0.22) 3px 5px 30px 0;

  /* Radius */
  --sk-radius-sm: 5px;
  --sk-radius-md: 8px;
  --sk-radius-lg: 12px;
  --sk-radius-pill: 980px;

  /* Layout */
  --sk-content-max: 980px;
  --sk-reading-max: 680px;
  --sk-nav-height: 48px;

  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --sk-bg-light: #1d1d1f;
    --sk-bg-dark: #000000;
    --sk-page-bg: #000000;
    --sk-surface: #1d1d1f;
    --sk-surface-muted: #2a2a2d;

    --sk-text-primary: #ffffff;
    --sk-text-body: rgba(255, 255, 255, 0.88);
    --sk-text-tertiary: rgba(255, 255, 255, 0.56);

    --sk-link: #2997ff;
    --sk-link-dark-bg: #2997ff;

    --sk-rule: rgba(255, 255, 255, 0.12);
    --sk-card-shadow: rgba(0, 0, 0, 0.6) 3px 5px 30px 0;

    color-scheme: dark;
  }
}

/* ---------- Reset + base ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  background: var(--sk-page-bg);
  color: var(--sk-text-primary);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'SF Pro Text',
    'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 17px;
  font-weight: 400;
  line-height: 1.47;
  letter-spacing: -0.022em;
  font-feature-settings: 'cv02', 'cv03', 'cv04', 'cv11';
}

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

a {
  color: var(--sk-link);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}
a:focus-visible {
  outline: 2px solid var(--sk-focus);
  outline-offset: 2px;
  border-radius: 2px;
}

button {
  font: inherit;
  cursor: pointer;
}

/* ---------- Typography scale ---------- */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 0.5em;
  color: var(--sk-text-primary);
  font-weight: 600;
  letter-spacing: -0.005em;
  line-height: 1.14;
}

.sk-display {
  font-size: clamp(40px, 6vw, 56px);
  line-height: 1.07;
  letter-spacing: -0.005em;
  font-weight: 600;
  margin: 0;
}

.sk-eyebrow {
  font-size: 14px;
  line-height: 1.29;
  letter-spacing: -0.016em;
  font-weight: 600;
  color: var(--sk-text-tertiary);
  margin: 0 0 12px;
}

.sk-subtitle {
  font-size: 21px;
  line-height: 1.24;
  letter-spacing: 0.011em;
  font-weight: 400;
  color: var(--sk-text-body);
  margin: 0;
}

.sk-caption {
  font-size: 14px;
  line-height: 1.43;
  letter-spacing: -0.016em;
  color: var(--sk-text-tertiary);
}

.sk-micro {
  font-size: 12px;
  line-height: 1.33;
  letter-spacing: -0.01em;
  color: var(--sk-text-tertiary);
}

/* Long-form article content */
article h1 { font-size: 40px; line-height: 1.10; }
article h2 { font-size: 28px; line-height: 1.14; letter-spacing: 0.007em; margin-top: 1.6em; }
article h3 { font-size: 21px; line-height: 1.19; letter-spacing: 0.011em; margin-top: 1.4em; }
article h4 { font-size: 17px; line-height: 1.24; font-weight: 600; margin-top: 1.2em; }

article p,
article ul,
article ol,
article blockquote {
  margin: 0 0 1em;
}

article ul,
article ol {
  padding-left: 1.4em;
}

article li + li { margin-top: 0.25em; }

article blockquote {
  border-left: 3px solid var(--sk-rule);
  padding: 2px 0 2px 18px;
  color: var(--sk-text-body);
}

article hr {
  border: 0;
  border-top: 1px solid var(--sk-rule);
  margin: 2.5em 0;
}

article strong, article b { font-weight: 600; }
article em, article i { font-style: italic; }

article a {
  color: var(--sk-link);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}
article a:hover { text-decoration-thickness: 2px; }

article img {
  border-radius: var(--sk-radius-lg);
  margin: 1.5em 0;
}

article table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5em 0;
  font-size: 14px;
}
article th,
article td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: 1px solid var(--sk-rule);
}
article th { font-weight: 600; }

article code {
  font-family: 'SF Mono', Menlo, Monaco, Consolas, 'Courier New', monospace;
  font-size: 0.9em;
  background: var(--sk-surface-muted);
  color: var(--sk-text-primary);
  padding: 2px 6px;
  border-radius: var(--sk-radius-sm);
}

::selection {
  background: var(--sk-accent);
  color: #ffffff;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
}