:root {
  --bg: #ffffff; --fg: #15181e; --muted: #5b6270; --line: #e3e6eb; --card: #f6f7f9;
  --accent: #2f6feb; --accent-fg: #ffffff;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f1115; --fg: #e9ecf1; --muted: #9aa3b2; --line: #262a33; --card: #171a21; --accent: #5b8ff5; --accent-fg: #0b1020; }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", "Helvetica Neue", Arial, sans-serif;
}
a { color: var(--accent); }
.wrap { width: min(1040px, 100% - 2.5rem); margin-inline: auto; }

.top { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding-block: 1.25rem; }
.brand { display: inline-flex; align-items: center; gap: .55rem; font-weight: 700; font-size: 1.2rem; color: var(--fg); text-decoration: none; }

.lang { position: relative; }
.lang summary { cursor: pointer; list-style: none; padding: .4rem .8rem; border: 1px solid var(--line); border-radius: 999px; font-size: .9rem; }
.lang summary::-webkit-details-marker { display: none; }
.lang summary::after { content: " ▾"; color: var(--muted); }
.lang ul {
  position: absolute; inset-inline-end: 0; top: calc(100% + .4rem); z-index: 10;
  margin: 0; padding: .4rem; list-style: none; min-width: 11rem; max-height: 70vh; overflow: auto;
  background: var(--bg); border: 1px solid var(--line); border-radius: .75rem; box-shadow: 0 8px 24px rgb(0 0 0 / .12);
}
.lang li a { display: block; padding: .35rem .6rem; border-radius: .5rem; color: var(--fg); text-decoration: none; }
.lang li a:hover, .lang li a:focus-visible { background: var(--card); }
.lang li a[aria-current] { font-weight: 700; }

.hero { padding-block: 3.5rem 2.5rem; text-align: center; }
.hero h1 { font-size: clamp(2rem, 5vw, 3.2rem); line-height: 1.15; margin: 0 0 1rem; letter-spacing: -.02em; }
.hero h1, .hero p, h2, h3 { text-wrap: balance; }
:lang(ja) { word-break: auto-phrase; }
.hero p { font-size: 1.15rem; color: var(--muted); max-width: 40rem; margin: 0 auto; }

h2 { font-size: 1.5rem; margin: 2.5rem 0 1.25rem; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 22rem), 1fr)); gap: 1.25rem; }
.card { display: flex; flex-direction: column; padding: 1.5rem; background: var(--card); border: 1px solid var(--line); border-radius: 1rem; }
.card-logo { border-radius: .9rem; }
.card h3 { margin: .9rem 0 .1rem; font-size: 1.25rem; }
.card p { margin: .4rem 0; }
.platforms { color: var(--muted); font-size: .9rem; }
.note { color: var(--muted); font-size: .95rem; }
.actions { display: flex; flex-wrap: wrap; gap: .6rem; margin-top: auto; padding-top: 1rem; }
.btn { display: inline-block; padding: .6rem 1.1rem; border-radius: .6rem; border: 1px solid var(--line); color: var(--fg); text-decoration: none; font-weight: 600; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.btn:hover { filter: brightness(1.06); }
.btn:focus-visible, .lang summary:focus-visible, .brand:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.principles { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 15rem), 1fr)); gap: 1.25rem; }
.principle h3 { margin: 0 0 .3rem; font-size: 1.05rem; }
.principle p { margin: 0; color: var(--muted); }

.foot { margin-top: 3.5rem; padding-block: 1.5rem 2.5rem; border-top: 1px solid var(--line); color: var(--muted); font-size: .9rem; }
.foot p { margin: 0; }