/* Palette: ai-iro (indigo, 藍 = "AI") accent on warm paper. */
:root {
  --ink: #24292f;
  --paper: #faf9f6;
  --card: #ffffff;
  --ai: #2f5d9e;      /* 藍色 accent */
  --ai-deep: #274a78;
  --muted: #6b7280;
  --line: #e5e2da;
}
@media (prefers-color-scheme: dark) {
  :root {
    --ink: #e6e6e3;
    --paper: #181a1f;
    --card: #20232a;
    --ai: #7ba3d6;
    --ai-deep: #9db9de;
    --muted: #9aa1ab;
    --line: #33363d;
  }
}
* { box-sizing: border-box; }
html { font-size: 100%; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Hiragino Kaku Gothic ProN", "Hiragino Sans", "Noto Sans JP", "Yu Gothic", "YuGothic", system-ui, sans-serif;
  line-height: 1.9;
  font-size: 1rem;
}
main, .site-header, .site-footer {
  max-width: 40rem;
  margin: 0 auto;
  padding: 0 1.25rem;
}
a { color: var(--ai); }
a:hover { color: var(--ai-deep); }
:focus-visible { outline: 3px solid var(--ai); outline-offset: 2px; }

.site-header { padding-top: 1.5rem; padding-bottom: 1rem; border-bottom: 1px solid var(--line); }
.site-title {
  display: inline-block;
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 4px solid var(--ai);
  padding-bottom: 0.1rem;
}
.site-header nav { margin-top: 0.75rem; display: flex; flex-wrap: wrap; gap: 1rem; }
.site-header nav a { text-decoration: none; }
.lang-switch { margin-left: auto; }

main { padding-top: 2rem; padding-bottom: 3rem; }
h1 { font-size: 1.5rem; line-height: 1.5; margin: 0 0 0.75rem; }
h2 { font-size: 1.15rem; margin-top: 2.5rem; }

/* Tip list */
.tip-list { list-style: none; padding: 0; margin: 1.5rem 0; }
.tip-list li { padding: 0.9rem 0; border-bottom: 1px solid var(--line); }
.tip-list a { text-decoration: none; font-weight: 600; }
.tip-list a:hover { text-decoration: underline; }
.tag {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--muted);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0 0.6em;
  margin-right: 0.4em;
}

/* Tip page */
.tip-header .tip-title-en { color: var(--muted); margin-top: -0.25rem; }
.tip-body p { background: var(--card); border-left: 4px solid var(--ai); padding: 0.75rem 1rem; border-radius: 0 6px 6px 0; }
.tip-body p strong:first-child { color: var(--ai-deep); }
.tip-en h2 { border-bottom: 1px solid var(--line); padding-bottom: 0.25rem; }
.tip-footer { margin-top: 2rem; color: var(--muted); font-size: 0.85rem; }
.tip-source { overflow-wrap: anywhere; }

.site-footer { border-top: 1px solid var(--line); padding-top: 1rem; padding-bottom: 2rem; color: var(--muted); font-size: 0.85rem; }

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}