:root { --bg: #f5f6f8; --ink: #1d2a33; --main: #24476b; --acc: #e0823f; --ok: #2e8b57; --ng: #c8423c; --card: #fff; --line: #dde2e8; --muted: #6b7782; }
* { box-sizing: border-box; }
html, body { margin: 0; background: var(--bg); color: var(--ink); font-family: system-ui, -apple-system, "Hiragino Sans", "Yu Gothic UI", "Noto Sans JP", sans-serif; font-size: 16px; line-height: 1.6; }
.top { position: sticky; top: 0; z-index: 2; display: flex; align-items: center; gap: 8px; background: var(--main); color: #fff; padding: 10px 14px; }
.top h1 { font-size: 18px; margin: 0; }
.back { background: none; border: 0; color: #fff; font-size: 22px; cursor: pointer; padding: 0 6px; }
main { max-width: 680px; margin: 0 auto; padding: 14px; }
h2 { font-size: 20px; margin: 10px 0; }
h3 { font-size: 16px; margin: 18px 0 8px; color: var(--main); }
.card { display: block; width: 100%; text-align: left; background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 14px; margin: 8px 0; font: inherit; color: inherit; cursor: pointer; }
.card.off { opacity: .55; cursor: default; }
.card small { color: var(--muted); display: block; }
.badge { float: right; font-size: 12px; background: #eef2f6; border-radius: 10px; padding: 2px 8px; color: var(--muted); }
.btn { display: block; width: 100%; padding: 13px; margin: 10px 0; border-radius: 12px; border: 0; background: var(--main); color: #fff; font: inherit; font-weight: 700; cursor: pointer; }
.btn.sub { background: #fff; color: var(--main); border: 2px solid var(--main); }
.q { white-space: pre-wrap; font-size: 17px; }
.src { color: var(--muted); font-size: 12px; margin: 4px 0 10px; }
.choice { display: flex; gap: 10px; width: 100%; text-align: left; background: #fff; border: 2px solid var(--line); border-radius: 12px; padding: 12px; margin: 8px 0; font: inherit; color: inherit; cursor: pointer; }
.choice b { color: var(--main); }
.choice.ok { border-color: var(--ok); background: #eef8f1; }
.choice.ng { border-color: var(--ng); background: #fbefee; }
.explain { background: #fff; border-left: 5px solid var(--acc); border-radius: 8px; padding: 12px; margin: 12px 0; white-space: pre-wrap; }
.fig { max-width: 100%; border: 1px solid var(--line); border-radius: 8px; margin: 8px 0; background: #fff; }
table { border-collapse: collapse; margin: 8px 0; background: #fff; font-size: 14px; }
td, th { border: 1px solid var(--line); padding: 4px 8px; }
.bar { height: 8px; background: var(--line); border-radius: 4px; overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--main); }
.row { display: flex; justify-content: space-between; gap: 10px; }
.timer { font-variant-numeric: tabular-nums; color: var(--muted); }
.center { text-align: center; }
.muted { color: var(--muted); font-size: 14px; }
.foot { text-align: center; color: var(--muted); font-size: 12px; padding: 20px 14px 30px; }
.grid { display: grid; grid-template-columns: repeat(10, 1fr); gap: 4px; }
.grid span { text-align: center; font-size: 12px; border-radius: 4px; padding: 2px 0; background: #eef2f6; }
.grid span.ok { background: #d6efdf; } .grid span.ng { background: #f6d6d3; }
table th { text-align: left; background: #eef2f6; white-space: nowrap; vertical-align: top; }