*, *::before, *::after { box-sizing: border-box; }
:where(h1, h2, h3, h4, h5, h6, p, ul, ol) { margin: 0; }
:where(ul, ol) { padding: 0; list-style: none; }
button { font: inherit; cursor: pointer; }
img { max-width: 100%; display: block; }

:root {
  font-family: Georgia, 'Times New Roman', 'Source Han Serif SC', 'Noto Serif SC', 'Songti SC', serif;
  --bg:             #F4ECD8;
  --fg:             #1A1A2E;
  --muted:          #7A6F5C;
  --rule:           #D4CCB8;
  --link:           #8C5A2B;
  --toggle-fill:    transparent;     /* light = hollow */
  --toggle-preview: var(--fg);       /* hover = filled (preview dark) */
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg:             #0F0F1A;
    --fg:             #EDE5D6;
    --muted:          #8B7E5E;
    --rule:           #2A2A3E;
    --link:           #A48D6F;
    --toggle-fill:    var(--fg);     /* dark = filled */
    --toggle-preview: transparent;   /* hover = hollow (preview light) */
  }
}

[data-theme="light"] {
  --bg:             #F4ECD8;
  --fg:             #1A1A2E;
  --muted:          #7A6F5C;
  --rule:           #D4CCB8;
  --link:           #8C5A2B;
  --toggle-fill:    transparent;
  --toggle-preview: var(--fg);
}
[data-theme="dark"] {
  --bg:             #0F0F1A;
  --fg:             #EDE5D6;
  --muted:          #8B7E5E;
  --rule:           #2A2A3E;
  --link:           #A48D6F;
  --toggle-fill:    var(--fg);
  --toggle-preview: transparent;
}



body {
  background: var(--bg);
  color: var(--fg);
  max-width: 48rem;
  margin: 4rem auto;
  padding: 0 1rem;
  line-height: 1.5;
}

h1, h2, h3 {
  color: var(--fg);
  margin-bottom: 0.8rem;
}

p {
    margin-top: 0.4rem;
    margin-bottom: 0.4rem;
}

a {
  color: var(--fg);
  text-decoration: underline;
  text-decoration-color: var(--link);
  text-decoration-thickness: 1.5px;
  text-underline-offset: 0.18em;
  text-decoration-skip-ink: auto;
}
a:hover {
  text-decoration-color: var(--fg);
  text-decoration-thickness: 2px;
}

hr {
  border: none;
  border-top: 1px solid var(--rule);
  margin: 2rem 0;
}

nav ul {
  list-style: none;
  padding: 0;
  display: flex;
  gap: 1rem;
}



.theme-toggle {
  width: 0.7rem;
  height: 0.7rem;
  padding: 0;
  border: 1.5px solid var(--fg);
  border-radius: 50%;
  background: var(--toggle-fill);
  cursor: pointer;
  vertical-align: baseline;
}
.theme-toggle:hover {
  background: var(--toggle-preview);
}

[data-lang="en"] [data-show-lang="zh"] { display: none; }
[data-lang="zh"] [data-show-lang="en"] { display: none; }

.lang-toggle {
  margin-left: auto;
  background: none;
  border: none;
  color: var(--muted);
  font: inherit;
  font-weight: normal;
  cursor: pointer;
  padding: 0;
  text-decoration: underline;
  text-decoration-color: var(--link);
  text-decoration-thickness: 1.5px;
  text-underline-offset: 0.18em;
}
.lang-toggle:hover {
  color: var(--fg);
  text-decoration-color: var(--fg);
}

.notes {
  margin: 0.4rem 0 1.5rem;
  padding: 0.2rem 0 0.2rem 1rem;
  border-left: 2px solid var(--rule);
  color: var(--muted);
  font-size: 0.9em;
  font-style: italic;
}
.notes p {
  margin: 0.2rem 0;
}