:root {
  --bg: #f9f9f9;
  --text: #1a1a1a;
  --link: #1a73e8;
  --link-hover: #0c5adf;
  --link-active: #0841a2;
  --border: #e0e0e0;
  --card-bg: #ffffff;
}

.theme-dark {
  --bg: #121212;
  --text: #eaeaea;
  --link: #8ab4f8;
  --link-hover: #a0c5ff;
  --link-active: #5e9fff;
  --border: #333;
  --card-bg: #1e1e1e;
}

.theme-light {
  --bg: #f9f9f9;
  --text: #1a1a1a;
  --link: #1a73e8;
  --link-hover: #0c5adf;
  --link-active: #0841a2;
  --border: #e0e0e0;
  --card-bg: #ffffff;
}

@media (prefers-color-scheme: dark) {
  :root:not(.theme-light) {
    --bg: #121212;
    --text: #eaeaea;
    --link: #8ab4f8;
    --link-hover: #a0c5ff;
    --link-active: #5e9fff;
    --border: #333;
    --card-bg: #1e1e1e;
  }
}

body {
  margin: 0;
  font-family: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
  padding: 2rem;
}

.container {
  max-width: 800px;
  margin: 0 auto;
}

h1 {
  font-size: 2.4rem;
  margin-bottom: 0.2em;
}

.subtitle {
  font-size: 1rem;
  color: #777;
  margin-bottom: 2em;
}

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

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

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

footer {
  margin-top: 3rem;
  font-size: 0.875rem;
  color: #888;
  text-align: center;
}

footer p {
  margin: 0.35rem 0;
}

.footer-note {
  max-width: 52rem;
  margin-inline: auto;
}

.theme-switcher {
  position: absolute;
  top: 1.2rem;
  right: 1.5rem;
  background: none;
  border: none;
  color: var(--link);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 0.3em 0.8em;
  border-radius: 20px;
  transition: background 0.2s;
}

.theme-switcher:hover {
  background: var(--card-bg);
  color: var(--link-hover);
}