/* 保護者のお勉強（/obenkyo/）：保護者むけの 読みもの。アプリの 空の 背景は 使わず、読みやすい 白い ページ */
@font-face { font-family: "Zen Maru Gothic"; src: url("/fonts/zen-maru-gothic-kana-700-normal.woff2") format("woff2"); font-weight: 700; font-display: swap; }
:root {
  --ob-ink: #26354a; --ob-sub: #5b6b82; --ob-line: #e3e8f0; --ob-bg: #fbfaf7; --ob-paper: #fff; --ob-accent: #2c6aa8; --ob-soft: #eef5fc; --ob-warm: #fff6e0;
  color-scheme: light;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body { margin: 0; background: var(--ob-bg); color: var(--ob-ink); font: 17px/1.9 system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif; letter-spacing: .02em; overflow-wrap: anywhere; }
a { color: var(--ob-accent); }
.ob-bar { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 10px max(16px, calc((100% - 760px) / 2)); background: var(--ob-paper); border-bottom: 1px solid var(--ob-line); }
.ob-brand { display: inline-flex; align-items: center; gap: 8px; color: var(--ob-ink); text-decoration: none; font-weight: 800; font-size: 20px; }
.ob-section { font-size: 14px; font-weight: 700; text-decoration: none; }
.ob-crumbs { max-width: 760px; margin: 12px auto 0; padding: 0 16px; font-size: 13px; color: var(--ob-sub); }
.ob-crumbs ol { display: flex; flex-wrap: wrap; gap: 4px; margin: 0; padding: 0; list-style: none; }
.ob-crumbs li + li::before { content: "›"; margin-right: 4px; }
.ob-main { max-width: 760px; margin: 0 auto; padding: 8px 16px 40px; }
h1 { font-family: "Zen Maru Gothic", system-ui, sans-serif; font-size: clamp(24px, 5vw, 32px); line-height: 1.5; margin: 12px 0 10px; }
.ob-eyecatch { display: block; width: 100%; height: auto; border-radius: 16px; margin: 4px 0 14px; border: 1px solid var(--ob-line); }
.ob-meta { display: flex; flex-wrap: wrap; gap: 4px 16px; font-size: 13px; color: var(--ob-sub); margin: 0 0 20px; }
.ob-intro { background: var(--ob-paper); border: 1px solid var(--ob-line); border-radius: 16px; padding: 4px 20px; }
.ob-know { font-weight: 800; margin-bottom: 6px; }
.ob-intro ul { background: var(--ob-soft); border-radius: 12px; padding: 12px 16px 12px 36px; }
.ob-toc { margin: 24px 0; padding: 14px 20px; background: var(--ob-paper); border: 1px solid var(--ob-line); border-radius: 16px; font-size: 15px; }
.ob-toc-title { margin: 0 0 4px; font-weight: 800; }
.ob-toc ol { margin: 0; padding-left: 22px; }
/* H2 の かたまりの 間の 区切り線 */
.ob-sec { padding-top: 28px; margin-top: 28px; border-top: 2px solid var(--ob-line); }
.ob-sec h2 { font-family: "Zen Maru Gothic", system-ui, sans-serif; font-size: clamp(21px, 4.4vw, 26px); line-height: 1.55; margin: 0 0 14px; padding-left: 12px; border-left: 6px solid var(--ob-accent); scroll-margin-top: 16px; }
.ob-sec h3 { font-size: 19px; line-height: 1.6; margin: 26px 0 8px; padding-bottom: 4px; border-bottom: 1px dashed var(--ob-line); }
p { margin: 0 0 1em; }
ul, ol { padding-left: 1.5em; margin: 0 0 1em; }
li { margin: 4px 0; }
.ob-table { overflow-x: auto; margin: 0 0 1.2em; border: 1px solid var(--ob-line); border-radius: 12px; background: var(--ob-paper); }
table { border-collapse: collapse; width: 100%; min-width: 520px; font-size: 15px; line-height: 1.7; }
th, td { padding: 10px 12px; border-bottom: 1px solid var(--ob-line); text-align: left; vertical-align: top; }
thead th { background: var(--ob-soft); white-space: nowrap; }
tbody th { background: #fafcff; font-weight: 700; min-width: 7.5em; }
tr:last-child > * { border-bottom: 0; }
.ob-bubble { display: flex; gap: 12px; align-items: flex-start; margin: 20px 0; }
.ob-bubble img { flex: none; border-radius: 50%; background: var(--ob-paper); border: 1px solid var(--ob-line); }
.ob-bubble > div { position: relative; flex: 1; background: var(--ob-warm); border-radius: 16px; padding: 10px 16px; }
.ob-bubble > div p { margin: 0; }
.ob-bubble-name { font-size: 13px; font-weight: 800; color: #9a6a00; }
.ob-author { display: flex; gap: 14px; align-items: flex-start; margin-top: 36px; padding: 16px 18px; background: var(--ob-paper); border: 1px solid var(--ob-line); border-radius: 16px; font-size: 15px; }
.ob-author img { flex: none; }
.ob-author-name { font-weight: 800; margin-bottom: 4px; }
.ob-cta { text-align: center; margin: 28px 0 0; }
.ob-cta a { display: inline-block; padding: 12px 24px; background: var(--ob-accent); color: #fff; font-weight: 800; text-decoration: none; border-radius: 999px; }
.ob-lead { color: var(--ob-sub); }
.ob-list { list-style: none; padding: 0; display: grid; gap: 14px; }
.ob-list a { display: grid; gap: 4px; padding: 16px 18px; background: var(--ob-paper); border: 1px solid var(--ob-line); border-radius: 16px; text-decoration: none; color: var(--ob-ink); }
.ob-list-title { font-weight: 800; font-size: 18px; color: var(--ob-accent); }
.ob-list-desc { font-size: 15px; }
.ob-list-date { font-size: 13px; color: var(--ob-sub); }
.ob-foot { max-width: 760px; margin: 0 auto; padding: 20px 16px 32px; border-top: 1px solid var(--ob-line); font-size: 14px; color: var(--ob-sub); }
.ob-foot nav { display: flex; flex-wrap: wrap; gap: 6px 16px; margin: 8px 0; }
.ob-copy { margin: 0; }
.ob-fig { margin: 8px 0 22px; }
.ob-fig svg { display: block; width: 100%; height: auto; font-family: "Zen Maru Gothic", system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif; }
.ob-fig figcaption { margin-top: 6px; font-size: 13px; color: var(--ob-sub); text-align: center; line-height: 1.6; }