/* ポータル・教材紹介ページ共通スタイル。
   ドリル本体(engine/style.css)と同じ配色トークンを使い、
   サイト全体で見た目の一貫性を保つ。 */

:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --surface-alt: #eef1f5;
  --text: #1f2933;
  --muted: #6b7684;
  --border: #dde2e8;
  --accent: #2f6fed;
  --new: #16875a;
  --new-bg: #e4f5ec;
  color-scheme: light dark;
}

/* OS設定によるダーク反映。data-theme="light" が明示されているときは無効化する
   (トグルボタンでの手動選択を優先するため)。 */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #14181d;
    --surface: #1c2229;
    --surface-alt: #20272f;
    --text: #e6eaef;
    --muted: #9aa5b1;
    --border: #2c343d;
    --accent: #6aa1ff;
    --new: #4fd398;
    --new-bg: #17301f;
  }
}

/* トグルボタンでの手動選択(localStorage、theme.js)。OS設定より優先する。 */
:root[data-theme="dark"] {
  --bg: #14181d;
  --surface: #1c2229;
  --surface-alt: #20272f;
  --text: #e6eaef;
  --muted: #9aa5b1;
  --border: #2c343d;
  --accent: #6aa1ff;
  --new: #4fd398;
  --new-bg: #17301f;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, 'Hiragino Sans', 'Noto Sans JP', sans-serif;
  line-height: 1.7;
}

a { color: var(--accent); }

/* --- ヘッダー ------------------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.site-header-inner {
  max-width: 72rem;
  margin: 0 auto;
  padding: .9rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.site-brand {
  display: flex;
  align-items: center;
  gap: .5rem;
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text);
  text-decoration: none;
}
.site-brand .mark { font-size: 1.3rem; }

.site-nav {
  display: flex;
  gap: 1.1rem;
  flex-wrap: wrap;
}
.site-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: .9rem;
}
.site-nav a:hover,
.site-nav a.current { color: var(--accent); }

.theme-toggle {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  border-radius: 2rem;
  padding: .4rem 1rem;
  font-size: .8rem;
  cursor: pointer;
  white-space: nowrap;
}
.theme-toggle:hover { border-color: var(--accent); }

/* --- 本文レイアウト(サイドバー付きマガジン風) ------------------------ */

.site-shell {
  max-width: 72rem;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

.hero { margin-bottom: 2rem; }
.hero h1 { font-size: 1.75rem; margin: 0 0 .6rem; }
.hero .lead { color: var(--muted); font-size: 1.05rem; max-width: 42rem; margin: 0; }

.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 2.5rem;
  align-items: start;
}
@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
}

.post-grid { display: grid; gap: 1.5rem; }

.post-card {
  display: block;
  border: 1px solid var(--border);
  border-radius: 1rem;
  padding: 1.5rem 1.6rem;
  background: var(--surface);
  text-decoration: none;
  color: inherit;
  transition: border-color .15s ease, transform .15s ease;
}
a.post-card:hover { border-color: var(--accent); transform: translateY(-2px); }

.post-card .eyebrow {
  display: inline-block;
  font-size: .75rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-bottom: .5rem;
}

.post-card h2 { margin: 0 0 .5rem; font-size: 1.15rem; color: var(--text); }
.post-card p { margin: 0; color: var(--muted); font-size: .92rem; }
.post-card > a {
  display: inline-block;
  margin-top: .8rem;
  color: var(--accent);
  font-weight: 600;
  font-size: .88rem;
  text-decoration: none;
}
.post-card > a:hover { text-decoration: underline; }

/* --- サイドバー ------------------------------------------------------ */

.sidebar { display: flex; flex-direction: column; gap: 1.5rem; }

.widget {
  border: 1px solid var(--border);
  border-radius: 1rem;
  padding: 1.25rem 1.4rem;
  background: var(--surface-alt);
}
.widget h3 {
  margin: 0 0 .8rem;
  font-size: .8rem;
  text-transform: uppercase;
  letter-spacing: .05em;
  color: var(--muted);
}
.widget ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: .55rem; }
.widget a { color: var(--text); text-decoration: none; font-size: .92rem; }
.widget a:hover { color: var(--accent); }
.widget p { margin: 0; font-size: .88rem; color: var(--muted); line-height: 1.6; }

/* --- 新着問題ウィジェット --------------------------------------------- */

.widget-new ul { gap: .9rem; }
.new-item a { display: flex; flex-direction: column; gap: .25rem; }
.new-item + .new-item { border-top: 1px dashed var(--border); padding-top: .9rem; }
.new-item-meta { display: flex; align-items: center; gap: .45rem; font-size: .72rem; color: var(--muted); }
.new-item-theme { color: var(--accent); font-weight: 600; }
.new-item-title { font-size: .92rem; font-weight: 600; color: var(--text); }
.new-item-q {
  font-size: .82rem; color: var(--muted);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.new-pill {
  display: inline-flex; align-items: center;
  font-size: .68rem; font-weight: 700; letter-spacing: .03em;
  color: var(--new); background: var(--new-bg);
  border-radius: .3rem; padding: .1rem .4rem;
}

/* --- フッター -------------------------------------------------------- */

.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 1.25rem;
  text-align: center;
  color: var(--muted);
  font-size: .8rem;
}
.site-footer .footer-notice {
  margin-top: .4rem;
  font-size: .75rem;
}

/* --- 汎用 ------------------------------------------------------------ */

.back {
  display: inline-block;
  margin-bottom: 1.5rem;
  font-size: .85rem;
  color: var(--muted);
  text-decoration: none;
}

.note {
  font-size: .85rem;
  color: var(--muted);
}

.hero .eyebrow {
  display: inline-block;
  font-size: .8rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-bottom: .5rem;
}

.btn {
  display: inline-block;
  font: inherit;
  border-radius: .5rem;
  padding: .7rem 1.4rem;
  border: 1px solid var(--border);
  background: var(--surface);
  color: inherit;
  text-decoration: none;
}
.btn-primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn-primary:hover { opacity: .9; }

/* --- パンくず ---------------------------------------------------------- */

.breadcrumb {
  font-size: .82rem;
  color: var(--muted);
  margin-bottom: 1.25rem;
}
.breadcrumb a { color: var(--muted); text-decoration: none; }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb [aria-current="page"] { color: var(--text); }

/* --- 解説記事(qa) ------------------------------------------------------ */

.qa-cta { margin-bottom: 2rem; }

.qa-category { margin-bottom: 2.5rem; }
.qa-category-heading { font-size: 1.1rem; margin: 0 0 1rem; }
.qa-theme-grid { grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr)); }
.qa-empty-note { margin: .8rem 0 0; font-size: .8rem; color: var(--muted); }

.qa-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 2rem; }

.qa-item {
  border: 1px solid var(--border);
  border-radius: 1rem;
  padding: 1.5rem 1.6rem;
  background: var(--surface);
  scroll-margin-top: 5rem;
}

.qa-eyebrow {
  margin: 0 0 .6rem;
  font-size: .78rem;
  color: var(--muted);
}

.qa-question { font-size: 1.05rem; font-weight: 600; margin-bottom: 1rem; }

.qa-text { white-space: pre-wrap; }

.qa-choices {
  list-style: none;
  margin: 0 0 1.25rem;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: .5rem;
}
.qa-choices li {
  border: 1px solid var(--border);
  border-radius: .5rem;
  padding: .6rem .9rem;
  font-size: .92rem;
}
.qa-choices li.is-answer {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  font-weight: 600;
}

.qa-answer {
  border-top: 1px solid var(--border);
  padding-top: 1rem;
  margin-top: .5rem;
}
.qa-answer-label {
  margin: 0 0 .4rem;
  font-size: .78rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .04em;
}

.qa-supplement {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px dashed var(--border);
}
.qa-supplement h3 {
  margin: 0 0 .5rem;
  font-size: .85rem;
  color: var(--muted);
}