:root {
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #1d1f23;
  --muted: #646b76;
  --line: #e2e5ea;
  --accent: #2f6fdb;
  --accent-soft: #e8f0fd;
  --key: #ffffff;
  --key-fn: #c9ced6;
  --board: #d6d9de;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131518;
    --card: #1d2024;
    --text: #eef0f3;
    --muted: #9aa1ab;
    --line: #2d3137;
    --accent: #4a86ec;
    --accent-soft: #1d2a40;
    --key: #3a3d44;
    --key-fn: #2a2d33;
    --board: #1b1d21;
    color-scheme: dark;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 16px/1.75 system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", sans-serif;
}
a { color: var(--accent); }
.nav {
  position: sticky; top: 0; z-index: 2; display: flex; align-items: center; justify-content: space-between;
  padding: 12px clamp(16px, 4vw, 40px); background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px); border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; color: var(--text); text-decoration: none; }
.logo {
  display: inline-grid; place-items: center; width: 32px; height: 32px; border-radius: 9px;
  background: var(--accent); color: #fff; font-size: 17px;
}
.nav nav { display: flex; align-items: center; gap: 18px; font-size: 14px; }
.nav nav a { color: var(--text); text-decoration: none; }
.nav nav a.pill { background: var(--accent); color: #fff; padding: 6px 14px; border-radius: 999px; font-weight: 600; }
section { max-width: 1040px; margin: 0 auto; padding: 56px clamp(16px, 4vw, 40px); }
.hero { display: grid; grid-template-columns: 1.2fr 1fr; gap: 48px; align-items: center; padding-top: 64px; }
.eyebrow { color: var(--accent); font-weight: 700; font-size: 14px; letter-spacing: .08em; margin: 0 0 8px; }
h1 { font-size: clamp(30px, 5vw, 46px); line-height: 1.25; margin: 0 0 18px; letter-spacing: -.01em; }
.lead { color: var(--muted); font-size: 17px; margin: 0 0 28px; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; }
.button {
  display: inline-block; padding: 12px 20px; border-radius: 10px; border: 1px solid var(--line);
  background: var(--card); color: var(--text); text-decoration: none; font-weight: 600;
}
.button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.button:hover { filter: brightness(1.05); }

/* 端末イメージ */
.phone {
  margin: 0; justify-self: center; width: min(340px, 100%); background: var(--board);
  border-radius: 22px; padding: 10px; box-shadow: 0 20px 50px rgba(0, 0, 0, .12); border: 1px solid var(--line);
}
.bar { display: flex; gap: 6px; padding: 8px 6px 12px; font-size: 15px; overflow: hidden; white-space: nowrap; }
.bar span { padding: 3px 10px; border-radius: 6px; }
.bar .sel { background: var(--accent); color: #fff; font-weight: 700; }
.keys {
  display: grid; grid-template-columns: .85fr 1fr 1fr 1fr .85fr; grid-template-rows: repeat(4, 52px); gap: 6px;
}
.keys span {
  display: grid; place-items: center; background: var(--key); border-radius: 8px; font-weight: 700; font-size: 18px;
  box-shadow: 0 1px 0 rgba(0, 0, 0, .12);
}
.keys .fn { background: var(--key-fn); font-weight: 500; font-size: 13px; }
.keys .accent { background: var(--accent); color: #fff; }
.keys .tall { grid-row: span 2; }

.features h2, .start h2 { font-size: 26px; margin: 0 0 24px; }
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.grid article { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 22px; }
.grid h3 { margin: 10px 0 6px; font-size: 17px; }
.grid p { margin: 0; color: var(--muted); font-size: 14.5px; }
.icon {
  width: 40px; height: 40px; border-radius: 10px; display: grid; place-items: center;
  background: var(--accent-soft); color: var(--accent); font-weight: 800;
}
.start ol { list-style: none; counter-reset: s; padding: 0; margin: 0; display: grid; gap: 12px; }
.start li {
  counter-increment: s; display: grid; grid-template-columns: 44px 150px 1fr; gap: 12px; align-items: baseline;
  background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 16px 20px;
}
.start li::before {
  content: counter(s); display: grid; place-items: center; width: 32px; height: 32px; border-radius: 50%;
  background: var(--accent); color: #fff; font-weight: 700; align-self: center;
}
.start li span { color: var(--muted); }
.dict-cta {
  display: flex; align-items: center; justify-content: space-between; gap: 24px; flex-wrap: wrap;
  background: var(--accent-soft); border-radius: 18px; margin-bottom: 56px; padding: 32px clamp(20px, 4vw, 40px);
}
.dict-cta h2 { margin: 0 0 6px; font-size: 22px; }
.dict-cta p { margin: 0; color: var(--muted); }
footer { text-align: center; color: var(--muted); font-size: 13px; padding: 24px 16px 40px; border-top: 1px solid var(--line); }
@media (max-width: 800px) {
  .hero { grid-template-columns: 1fr; gap: 32px; padding-top: 40px; }
  .grid { grid-template-columns: 1fr; }
  .start li { grid-template-columns: 40px 1fr; }
  .start li span { grid-column: 2; }
  .nav nav a:not(.pill) { display: none; }
}