:root {
  --bg: #ffffff;
  --text: #111111;
  --muted: #666666;
  --line: #dddddd;
  --link: #1a4fb8;
  --link-hover: #123a88;
  --button-bg: #111111;
  --button-text: #f5f5f5;
}

html[data-theme='dark'] {
  --bg: #111111;
  --text: #f5f5f5;
  --muted: #b3b3b3;
  --line: #2a2a2a;
  --link: #8ab4ff;
  --link-hover: #a8c7ff;
  --button-bg: #f5f5f5;
  --button-text: #111111;
}

* {
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  margin:0 auto;
  background: var(--bg);
  color: var(--text);
  font-family: "Open Sans", Arial, sans-serif;
  line-height: 1.7;
  transition:
    background-color 0.2s ease,
    color 0.2s ease;
}

.page {
  width: min(720px, calc(100% - 40px));
  margin: 56px auto 80px;
}

/* Header */
.header {
  margin-bottom: 48px;
}

.header h1 {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.header .subtitle {
  margin: 0;
  color: var(--muted);
  font-size: 2rem;
}

.header img {
  width: 180px;
  height: auto;
  margin-top: 16px;
  border-radius: 8px;
  display: block;
}

/* Sections */
.section {
  padding: 24px 0;
  border-top: 1px solid var(--line);
}

.section:first-of-type {
  border-top: none;
  padding-top: 0;
}

.section h2 {
  margin-bottom: 14px;
  font-size: 1.1rem;
  font-weight: 700;
}





/* Links */
a {
  color: var(--link);
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color 0.15s;
}

a:hover {
  color: var(--link-hover);
}


/* Blockquote */
blockquote {
  color: var(--muted);
  border-left: 3px solid var(--line);
  padding-left: 16px;
  margin: 24px 0;
  font-style: italic;
}

blockquote span {
  display: block;
  margin-bottom: 8px;
}

blockquote author {
  display: block;
  font-size: 0.85rem;
  font-style: normal;
  color: var(--text);
}


/* Footer */
.footer {
  padding-top: 20px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.95rem;
}

/* Responsive */
@media (max-width: 640px) {
  .page {
    width: calc(100% - 28px);
    margin: 32px auto 56px;
  }

  .header h1 {
    font-size: 1.85rem;
  }

  .section {
    padding: 20px 0;
  }

  .header img {
    width: 140px;
  }
}

/* toggle-button */
#theme-toggle {
  position: fixed;
  top: 16px;
  right: 16px;
  border: 1px solid var(--line);
  background: var(--button-bg);
  color: var(--button-text);
  font: inherit;
  cursor: pointer;
  border-radius: 4px;
}