:root {
  --ink: #1c1915;
  --muted: #5c5348;
  --paper: #f6f1e7;
  --card: #fffdf8;
  --line: #e2d8c8;
  --red: #b42318;
  --indigo: #1e3a5f;
  --ok: #1f7a3a;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "IBM Plex Sans", "Noto Sans JP", sans-serif;
  font-size: 17px;
  line-height: 1.6;
}
a { color: var(--indigo); }
.wrap { width: min(760px, calc(100% - 32px)); margin: 0 auto; }
.nav { display: flex; justify-content: space-between; align-items: center; padding: 18px 0; gap: 16px; }
.brand { display: flex; align-items: center; gap: 10px; color: inherit; text-decoration: none; font-weight: 600; }
.mark { width: 36px; height: 36px; border-radius: 8px; display: block; object-fit: cover; }
.nav-links { display: flex; gap: 16px; }
.nav-links a { color: var(--muted); text-decoration: none; }
h1 { font-family: "Fraunces", "Noto Serif JP", serif; font-size: clamp(2.2rem, 5vw, 3.6rem); line-height: 1; letter-spacing: -0.03em; margin: 8px 0 12px; }
.kicker { color: var(--red); letter-spacing: 0.12em; text-transform: uppercase; font-size: 0.78rem; font-weight: 600; margin: 0; }
.lede { color: var(--muted); max-width: 62ch; }
.tabs { display: flex; gap: 8px; margin: 18px 0; }
.tab, .dir {
  border: 1px solid var(--line); background: var(--card); border-radius: 999px;
  padding: 8px 14px; font: inherit; cursor: pointer; color: var(--ink);
}
.tab[aria-selected="true"], .dir[aria-pressed="true"] { background: var(--ink); color: #fff; border-color: var(--ink); }
.stats {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin: 12px 0 16px;
}
.stat { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 10px 12px; }
.stat b { display: block; font-size: 1.25rem; }
.stat span { color: var(--muted); font-size: 0.78rem; letter-spacing: 0.04em; text-transform: uppercase; }
.progress { height: 8px; background: var(--line); border-radius: 999px; overflow: hidden; margin-bottom: 16px; }
.progress i { display: block; height: 100%; width: 0; background: var(--red); }
.board { background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 22px; }
.prompt { font-family: "Noto Serif JP", serif; font-size: clamp(3rem, 10vw, 5rem); line-height: 1; margin: 8px 0 18px; text-align: center; }
.options { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.opt {
  min-height: 72px; border: 1px solid var(--line); border-radius: 12px; background: #fff;
  font: inherit; font-size: 1.5rem; cursor: pointer; color: var(--ink);
}
.opt.kana { font-family: "Noto Serif JP", serif; font-size: 2rem; }
.opt.correct { background: #e8f6ec; border-color: var(--ok); color: var(--ok); }
.opt.wrong { background: #fdecec; border-color: var(--red); color: var(--red); }
.feedback { min-height: 72px; margin-top: 14px; }
.feedback p { margin: 0 0 8px; }
.next, .ghost {
  border: 0; border-radius: 999px; background: var(--red); color: #fff; font: inherit; font-weight: 600;
  padding: 10px 16px; cursor: pointer;
}
.ghost { background: transparent; color: var(--red); border: 2px solid var(--red); padding: 8px 14px; }
.hidden { display: none; }
.section { padding: 28px 0; }
h2 { font-family: "Fraunces", serif; font-size: 1.7rem; margin: 0 0 8px; }
footer { border-top: 1px solid var(--line); color: var(--muted); padding: 22px 0 36px; }
@media (max-width: 700px) {
  .stats { grid-template-columns: 1fr 1fr; }
  .nav { flex-direction: column; align-items: flex-start; }
}