/* テラコヤ 無料学習ページ。外部フォントは使わず、端末のフォントで表示する。色はテラコヤのブランド（緑・黄色） */
:root {
  --leaf-700: #256d36; --leaf-600: #2f8a45; --leaf-100: #e4f3e6; --leaf-50: #f2f9f2;
  --sun-400: #f4cf43; --sun-300: #f8de7c; --sun-100: #fdf4d6;
  --coral-500: #f2a07d; --coral-100: #fce9e0; --danger: #b42318; --danger-bg: #fdecea;
  --paper-50: #fffdf8; --paper-100: #f8f5ec; --line: #e6dfcd;
  --ink: #111; --ink-soft: #3b3a36; --muted: #6b6860;
  --radius: 18px;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper-100); color: var(--ink);
  font-family: system-ui, -apple-system, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic UI", "Yu Gothic", Meiryo, sans-serif;
  font-size: 17px; line-height: 1.85; letter-spacing: 0.02em;
}
a { color: var(--leaf-700); text-underline-offset: 3px; }
a:focus-visible, button:focus-visible, summary:focus-visible, input:focus-visible + .mark { outline: 3px solid var(--sun-400); outline-offset: 2px; }
img { max-width: 100%; height: auto; }
.preview-bar { background: var(--coral-500); color: var(--ink); text-align: center; font-weight: 700; font-size: 14px; padding: 8px 16px; }

.site-header { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 10px 16px; background: rgba(255, 253, 248, 0.95); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 10; }
.brand { display: flex; align-items: center; gap: 8px; text-decoration: none; color: var(--ink); min-height: 44px; }
.brand b { display: block; color: var(--leaf-700); font-size: 19px; line-height: 1.1; letter-spacing: 0.08em; }
.brand small { display: block; font-size: 11px; color: var(--muted); line-height: 1.2; }
.header-link { font-size: 14px; font-weight: 700; min-height: 44px; display: inline-flex; align-items: center; }

main { max-width: 760px; margin: 0 auto; padding: 20px 16px 48px; }
h1, h2, h3 { line-height: 1.45; letter-spacing: 0.02em; }
.page-title { font-size: 26px; margin: 8px 0 8px; }
.eyebrow { color: var(--leaf-700); font-weight: 700; font-size: 13px; letter-spacing: 0.12em; margin: 0; }
.lead { color: var(--ink-soft); }
.note { color: var(--muted); font-size: 14px; }
.small { font-size: 12px; }
.section-title { font-size: 21px; margin: 32px 0 12px; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.tag { background: var(--leaf-600); color: #fff; font-size: 13px; padding: 2px 10px; border-radius: 999px; }
.tag-sun { background: var(--sun-400); color: var(--ink); }
.marker { background: linear-gradient(transparent 60%, var(--sun-300) 60%); }

.hero { background: linear-gradient(135deg, var(--paper-50), var(--leaf-50) 60%, var(--sun-100)); border: 2px solid var(--leaf-100); border-radius: 24px; padding: 24px 20px; }
.hero h1 { font-size: 30px; margin: 8px 0; }
.facts { display: flex; flex-wrap: wrap; gap: 8px; list-style: none; padding: 0; margin: 12px 0 0; }
.facts li { background: #fff; border: 1px solid var(--line); border-radius: 999px; padding: 2px 12px; font-size: 14px; font-weight: 700; color: var(--leaf-700); }

.subject-grid, .unit-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; }
.subject-card, .unit-card { display: block; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px; text-decoration: none; color: var(--ink); transition: transform 0.15s ease, box-shadow 0.15s ease; min-height: 56px; }
.subject-card:hover, .unit-card:hover { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(47, 138, 69, 0.12); }
.subject-name, .unit-title { display: block; font-weight: 800; font-size: 18px; }
.subject-desc { display: block; color: var(--ink-soft); font-size: 14px; }
.subject-meta, .unit-meta { display: block; color: var(--muted); font-size: 13px; }
.pill { display: inline-block; background: var(--leaf-100); color: var(--leaf-700); font-weight: 700; font-size: 12px; border-radius: 999px; padding: 0 8px; margin-right: 6px; }
.field-title { font-size: 17px; color: var(--leaf-700); margin: 24px 0 8px; }

.steps { counter-reset: s; list-style: none; padding: 0; display: grid; gap: 8px; }
.steps li { counter-increment: s; background: #fff; border: 1px solid var(--line); border-radius: 14px; padding: 10px 14px 10px 52px; position: relative; }
.steps li::before { content: counter(s); position: absolute; left: 14px; top: 12px; width: 26px; height: 26px; border-radius: 50%; background: var(--leaf-600); color: #fff; font-weight: 800; display: grid; place-items: center; font-size: 14px; }
.steps b { display: block; }
.steps span { color: var(--muted); font-size: 14px; }

.crumbs { font-size: 14px; display: flex; flex-wrap: wrap; gap: 6px; align-items: center; color: var(--muted); }
.crumbs a { min-height: 44px; display: inline-flex; align-items: center; }
.toc { display: flex; flex-wrap: wrap; gap: 6px; margin: 12px 0; }
.toc a { background: #fff; border: 1px solid var(--line); border-radius: 999px; padding: 6px 12px; font-size: 14px; font-weight: 700; text-decoration: none; min-height: 40px; display: inline-flex; align-items: center; }
.box { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 18px; margin: 16px 0; }
.box h2 { font-size: 18px; margin: 0 0 6px; }
.goals { border-left: 6px solid var(--leaf-600); }
.example { background: var(--sun-100); border-color: var(--sun-300); }
.review { background: var(--leaf-50); border-color: var(--leaf-100); }
.lesson { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 18px; margin: 12px 0; }
.lesson h3 { font-size: 18px; margin: 0 0 4px; color: var(--leaf-700); }
.lesson p { margin: 0; }
details > summary { cursor: pointer; font-weight: 700; color: var(--leaf-700); min-height: 44px; display: flex; align-items: center; }
.steps-list li { margin: 4px 0; }
.example-answer { background: #fff; border-radius: 12px; padding: 8px 12px; }

.problem { border: 1px solid var(--line); border-radius: var(--radius); background: #fff; padding: 16px; margin: 14px 0; min-width: 0; }
.problem legend { padding: 0 6px; }
.qnum { background: var(--ink); color: #fff; border-radius: 8px; padding: 2px 10px; font-weight: 800; font-size: 14px; }
.passage { margin: 6px 0 10px; padding: 12px 14px; background: var(--paper-100); border-left: 4px solid var(--sun-400); border-radius: 0 12px 12px 0; }
.passage[lang="en"] { font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; letter-spacing: 0; line-height: 1.7; }
.question { font-weight: 700; margin: 4px 0 10px; }
.choices { display: grid; gap: 8px; }
.choice { position: relative; display: flex; align-items: flex-start; gap: 10px; border: 2px solid var(--line); border-radius: 14px; padding: 10px 12px; cursor: pointer; min-height: 52px; background: var(--paper-50); }
.choice input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.choice .mark { flex: none; width: 28px; height: 28px; border-radius: 50%; border: 2px solid var(--line); display: grid; place-items: center; font-weight: 800; font-size: 14px; background: #fff; }
.choice:has(input:checked) { border-color: var(--leaf-600); background: var(--leaf-50); }
.choice:has(input:checked) .mark { background: var(--leaf-600); border-color: var(--leaf-600); color: #fff; }
/* 答え合わせ後：選んだ印より、正誤の色を優先する */
.choice.is-correct, .choice.is-correct:has(input:checked) { border-color: var(--leaf-600); background: var(--leaf-100); }
.choice.is-correct .mark { background: var(--leaf-600); border-color: var(--leaf-600); color: #fff; }
.choice.is-wrong, .choice.is-wrong:has(input:checked) { border-color: var(--danger); background: var(--danger-bg); }
.choice.is-wrong .mark, .choice.is-wrong:has(input:checked) .mark { background: var(--danger); border-color: var(--danger); color: #fff; }
.choice-text { padding-top: 1px; }
.actions { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 10px; }
.result { margin: 0; font-weight: 800; }
.result.ok { color: var(--leaf-700); }
.result.ng { color: var(--danger); }
.answer { margin-top: 8px; background: var(--paper-100); border-radius: 12px; padding: 4px 12px; }
.answer p { margin: 6px 0; }
.js .answer:not([open]) > summary { display: none; }

.btn { appearance: none; border: 2px solid var(--leaf-600); background: #fff; color: var(--leaf-700); border-radius: 999px; padding: 10px 18px; font: inherit; font-weight: 800; font-size: 16px; min-height: 48px; cursor: pointer; text-decoration: none; display: inline-flex; align-items: center; justify-content: center; gap: 6px; }
.btn.primary, .btn.check { background: var(--leaf-600); color: #fff; }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn:hover:not(:disabled) { transform: translateY(-1px); }
.next { display: grid; gap: 10px; margin: 28px 0 12px; }
.mistakes li { margin: 4px 0; }
.credit { color: var(--muted); font-size: 12px; }
.score .score-text { font-size: 20px; font-weight: 800; }

.frac { display: inline-flex; flex-direction: column; align-items: center; vertical-align: middle; line-height: 1.15; margin: 0 2px; font-size: 0.92em; }
.frac .num { border-bottom: 1.5px solid currentColor; padding: 0 3px; }
.frac .den { padding: 0 3px; }
sup, sub { line-height: 0; }

.site-footer { border-top: 1px solid var(--line); background: var(--paper-50); padding: 20px 16px 32px; font-size: 13px; color: var(--muted); text-align: center; }
.site-footer p { max-width: 720px; margin: 4px auto; }
.empty { text-align: center; padding: 32px 0; }

@media (min-width: 720px) {
  main { padding-top: 32px; }
  .hero { padding: 36px 36px; }
  .hero h1 { font-size: 38px; }
  .page-title { font-size: 30px; }
  .subject-grid { grid-template-columns: repeat(2, 1fr); }
  .next { grid-template-columns: 1fr auto; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
  .subject-card:hover, .unit-card:hover, .btn:hover:not(:disabled) { transform: none; }
}

/* 公開前の確認ページ（確認用ビルドだけで使う） */
.preview-bar a { color: var(--ink); font-weight: 800; }
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); }
.review-table { border-collapse: collapse; width: 100%; min-width: 640px; font-size: 14px; }
.review-table th, .review-table td { border-bottom: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
.review-table th { background: var(--paper-100); }
.review-table tr.is-first td { background: var(--sun-100); }
.review-table a { display: inline-block; min-height: 32px; padding-top: 4px; }
.sheet-choices { list-style: none; padding: 0; margin: 8px 0; display: grid; gap: 6px; }
.sheet-choices li { border: 1px solid var(--line); border-radius: 12px; padding: 8px 12px; }
.sheet-choices li.is-answer { border: 2px solid var(--leaf-600); background: var(--leaf-50); }
.pill-before { background: var(--coral-100); color: var(--danger); }
.revision p { margin: 6px 0; }
code { font-size: 0.9em; background: var(--paper-100); border-radius: 6px; padding: 0 4px; overflow-wrap: anywhere; }