:root {
  color-scheme: light;
  --color-bg: #ffffff;
  --color-bg-soft: #f5f6f8;
  --color-bg-glass: rgba(255, 255, 255, 0.78);
  --color-fg: #1d1f24;
  --color-fg-soft: #4f5661;
  --color-line: #cfd5de;
  --color-line-soft: #e1e5eb;
  --color-accent: #0066cc;
  --color-accent-hover: #0055aa;
  --color-hero-start: #17191f;
  --color-hero-end: #5e656e;
  --color-button-primary-hover: #000000;
  --color-prose: #2b313a;

  --max-width: 1080px;
  --gutter: clamp(20px, 4vw, 48px);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;

  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 14px 32px rgba(15, 23, 42, 0.1);

  --font-sans: "Helvetica Neue", "HelveticaNeue", Helvetica, Arial, sans-serif;
  --font-mono: "SF Mono", ui-monospace, "Menlo", Consolas, monospace;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

:root[data-theme="light"] {
  color-scheme: light;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --color-bg: #0d1117;
  --color-bg-soft: #151b23;
  --color-bg-glass: rgba(13, 17, 23, 0.78);
  --color-fg: #f3f4f6;
  --color-fg-soft: #c1c8d2;
  --color-line: #364152;
  --color-line-soft: #242c38;
  --color-accent: #66adff;
  --color-accent-hover: #8fc2ff;
  --color-hero-start: #ffffff;
  --color-hero-end: #aeb7c2;
  --color-button-primary-hover: #dbe2ea;
  --color-prose: #e5e9f0;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.45);
  --shadow-md: 0 18px 36px rgba(0, 0, 0, 0.35);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --color-bg: #0d1117;
    --color-bg-soft: #151b23;
    --color-bg-glass: rgba(13, 17, 23, 0.78);
    --color-fg: #f3f4f6;
    --color-fg-soft: #c1c8d2;
    --color-line: #364152;
    --color-line-soft: #242c38;
    --color-accent: #66adff;
    --color-accent-hover: #8fc2ff;
    --color-hero-start: #ffffff;
    --color-hero-end: #aeb7c2;
    --color-button-primary-hover: #dbe2ea;
    --color-prose: #e5e9f0;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.45);
    --shadow-md: 0 18px 36px rgba(0, 0, 0, 0.35);
  }
}

*, *::before, *::after { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  background-color: var(--color-bg);
}

body {
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 17px;
  line-height: 1.5;
  color: var(--color-fg);
  background: var(--color-bg);
  letter-spacing: -0.003em;
  transition: background-color 0.2s var(--ease), color 0.2s var(--ease);
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin: 0 0 0.4em;
  color: var(--color-fg);
}

h1 { font-size: clamp(40px, 6vw, 72px); font-weight: 700; letter-spacing: -0.035em; }
h2 { font-size: clamp(28px, 3.5vw, 44px); font-weight: 600; letter-spacing: -0.025em; }
h3 { font-size: clamp(22px, 2.4vw, 28px); font-weight: 500; }
h4 { font-size: 20px; font-weight: 500; }

p { margin: 0 0 1em; }

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s var(--ease);
}
a:hover { color: var(--color-accent-hover); }

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

::selection { background: var(--color-fg); color: var(--color-bg); }