/* わたしの HP の共通部品 (b1・b2 で共通)。色と見出し・ファーストビューは各案の style.css */
:root{
  --ink:#1f2637; --sub:#566074; --line:#e7e1d4; --paper:#fff; --tint:#fffaf0;
  --yellow:#f2b33d; --yellow-soft:#fde9b8; --yellow-ink:#7a4f00;
  --acc:var(--ink); --r:18px; color-scheme:light;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;background:var(--paper);color:var(--ink);
  font:500 16px/1.8 "Zen Maru Gothic","Hiragino Maru Gothic ProN","Noto Sans CJK JP",sans-serif;
  -webkit-text-size-adjust:100%;overflow-x:hidden}
img,video,iframe{max-width:100%;display:block}
img,video{height:auto}
a{color:inherit;text-underline-offset:3px}
:focus-visible{outline:3px solid #2a5fc4;outline-offset:3px;border-radius:6px}
.skip{position:absolute;left:-999px;top:0;background:var(--ink);color:#fff;padding:8px 14px;z-index:20}
.skip:focus{left:8px;top:8px}
.wrap{max-width:1100px;margin:0 auto;padding:0 20px}
h1,h2,h3{line-height:1.35;font-weight:900;letter-spacing:.02em;word-break:auto-phrase;text-wrap:balance}
.ptitle{word-break:auto-phrase}
.nw{display:inline-block}
.vh{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.small{font-size:14px;color:var(--sub)}
.sub{color:var(--sub);margin:0 0 14px}

.draftbar{background:#23211e;color:#fff;font-size:13px;text-align:center;padding:6px 12px}
.draftbar a{color:#fff}.draftbar span{opacity:.75}

/* ヘッダー */
.top{border-bottom:1px solid var(--line);background:var(--paper)}
.top-in{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:62px;flex-wrap:wrap}
.brand img{height:40px;width:auto}
.top-nav{display:flex;gap:4px 16px;font-weight:700;font-size:14px;flex-wrap:wrap}
.top-nav a{text-decoration:none;padding:6px 0}
.top-nav a[aria-current]{text-decoration:underline;text-decoration-thickness:3px;text-decoration-color:var(--yellow)}
/* スマホ幅はロゴの下に1段で4つ全部 (前は「トップ」「お問い合わせ」を隠していた・2026-09-27) */
@media (max-width:520px){.top-in{padding-top:8px;gap:0}.top-nav{width:100%;justify-content:space-between;border-top:1px solid var(--line);margin-top:6px}.top-nav a{padding:8px 0}}

/* 先生の記号 = 動画の名札と同じ「丸の中の1文字」 */
.mk{--g1:#ccc;--g2:#999;--c:#333;flex:none;display:inline-grid;place-items:center;width:52px;height:52px;border-radius:50%;
  background:radial-gradient(circle,#fff 0 60%,transparent 61%),linear-gradient(135deg,var(--g1),var(--g2));
  color:var(--c);font:400 25px/1 "Mochiy Pop One","Zen Maru Gothic",sans-serif;box-shadow:0 2px 6px rgba(31,38,55,.15)}
.mk.sm{width:32px;height:32px;font-size:15px;box-shadow:none}
.mk-yui{--g1:#FF6FAE;--g2:#9B7BFF;--c:#E83C7C}
.mk-kyohei{--g1:#2B6BE0;--g2:#1B2A4A;--c:#2B6BE0}
.mk-aoi{--g1:#6CC6B4;--g2:#8AA9F0;--c:#2E8F7A}
.mk-next{--g1:#e3dccb;--g2:#cfc5ad;--c:#8a7c58}
.marks{display:inline-flex}.marks .mk{margin-right:-6px;border:2px solid #fff}

/* タグ */
.tags{display:flex;flex-wrap:wrap;gap:6px;margin:0 0 10px;padding:0}
.tag{font-size:13px;font-weight:700;border-radius:99px;padding:1px 10px;background:#f1eee6;color:#4a5264}
.tag-grade{background:var(--ink);color:#fff}
.tag-unit{background:var(--yellow-soft);color:var(--yellow-ink)}

/* ボタン */
.cta{display:flex;flex-wrap:wrap;gap:10px}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:50px;padding:0 22px;border-radius:99px;font-weight:900;text-decoration:none;font-size:16px}
.btn-main{background:var(--acc);color:#fff}
.btn-line{background:#fff;color:var(--ink);border:2px solid var(--ink)}

/* 図 */
.fig{background:#fff;border:1px solid var(--line);border-radius:14px;padding:8px;width:100%;height:auto}

/* 問題カード */
.pgrid{list-style:none;margin:0;padding:0;display:grid;gap:14px;grid-template-columns:repeat(auto-fill,minmax(250px,1fr))}
.pcard a{display:flex;flex-direction:column;height:100%;text-decoration:none;background:#fff;border:1px solid var(--line);border-radius:var(--r);overflow:hidden;transition:transform .15s}
.pcard a:hover{transform:translateY(-2px);box-shadow:0 8px 20px rgba(31,38,55,.1)}
@media (prefers-reduced-motion:reduce){.pcard a{transition:none}.pcard a:hover{transform:none}}
.pfig{display:block;background:#fff;border-bottom:1px solid var(--line);aspect-ratio:4/3;padding:10px}
.pfig img{width:100%;height:100%;object-fit:contain}
.pbody{display:flex;flex-direction:column;gap:4px;padding:12px 14px 14px;flex:1}
.pbody .tags{margin:0}
.ptitle{font-size:18px;line-height:1.45}
.pmeta{display:flex;align-items:center;gap:12px;margin-top:auto;padding-top:6px;font-size:13px;color:var(--sub)}
.units{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:0 0 18px;font-size:14px;color:var(--sub)}
.chip{display:inline-flex;align-items:center;min-height:36px;padding:0 14px;border-radius:99px;border:1.5px solid var(--ink);color:var(--ink);text-decoration:none;font-weight:700;background:#fff}
.chip:hover{background:var(--yellow-soft)}

/* 節 */
.sec{padding:52px 0}
.sec h2{font-size:clamp(22px,6vw,32px);margin:0 0 10px}
.sec-lead{color:var(--sub);margin:0 0 22px;max-width:44em}
.sec-row{display:flex;align-items:baseline;justify-content:space-between;gap:12px}
.more{font-weight:900;white-space:nowrap}

.tlist{list-style:none;margin:0;padding:0;display:grid;gap:12px}
.tlist li{display:flex;align-items:center;gap:14px;background:#fff;border:1px solid var(--line);border-radius:16px;padding:12px 16px}
.tlist b{display:block;font-size:18px}.tlist span{color:var(--sub);font-size:14.5px}
.tlist .next{background:transparent;border-style:dashed}
@media (min-width:860px){.tlist{grid-template-columns:repeat(3,1fr)}.tlist li{flex-direction:column;align-items:flex-start}}

.appnote{display:flex;gap:10px;align-items:flex-start;margin:0;border:2px dashed var(--yellow);border-radius:14px;padding:12px 16px;background:#fff}
.appnote .dot{flex:none;width:10px;height:10px;border-radius:50%;background:var(--yellow);margin-top:9px}
.sec-app{padding:0 0 8px}

.sns{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:1fr 1fr;gap:10px;max-width:640px}
.sns a{display:flex;align-items:center;justify-content:center;min-height:52px;border-radius:14px;border:2px solid var(--ink);font-weight:900;text-decoration:none;background:#fff}
.sns a:hover{background:var(--yellow-soft)}
@media (min-width:860px){.sns{grid-template-columns:repeat(4,1fr);max-width:none}}
.sec-contact{background:var(--tint)}
.mail{display:inline-block;font-size:clamp(20px,6vw,28px);font-weight:900;text-decoration:none;border-bottom:5px solid var(--yellow);line-height:1.3}

/* 問題のページ */
.page{padding-top:18px;padding-bottom:48px}
.page h1{font-size:clamp(25px,6.6vw,38px);margin:6px 0 10px}
.crumb{font-size:13.5px;color:var(--sub)}
.crumb a{color:var(--sub)}
.blk{margin:26px 0}
.blk h2{font-size:clamp(20px,5.4vw,26px);margin:0 0 6px}
.problem{background:var(--tint);border-radius:22px;padding:18px}
.prob-in{display:grid;gap:16px}
.prob-text p{margin:0 0 8px;font-size:16.5px}
.qs{margin:0 0 10px;padding-left:1.8em;font-weight:700}
.qs li{margin-bottom:4px}
.given summary,.ans summary{cursor:pointer;font-weight:700}
.given{font-size:14.5px;color:var(--sub)}
.given ul{margin:6px 0 0;padding-left:1.2em}
.pdf{display:flex;flex-wrap:wrap;align-items:center;gap:8px 14px;margin:16px 0 0}
.pdf span{font-size:13.5px;color:var(--sub)}
@media (min-width:860px){.problem{padding:26px}.prob-in{grid-template-columns:1fr 1fr;align-items:start;gap:28px}}

.vrow{list-style:none;margin:0 -20px;padding:4px 20px 12px;display:grid;grid-auto-flow:column;grid-auto-columns:minmax(220px,66%);gap:14px;overflow-x:auto;scroll-snap-type:x mandatory}
.vcard{scroll-snap-align:center}
@media (min-width:860px){.vrow{grid-auto-flow:row;grid-template-columns:repeat(3,1fr);margin:0;padding:0;overflow:visible}}
.vid{border-radius:16px;overflow:hidden;background:#000}
.vid.vert video,.vid.vert iframe{width:100%;aspect-ratio:9/16;border:0}
.vid.wide video,.vid.wide iframe{width:100%;aspect-ratio:16/9;border:0}
.vwho{display:flex;align-items:center;gap:8px;margin:8px 2px 0;flex-wrap:wrap}
.vwho b{font-size:17px}.vwho>span:not(.mk){font-size:13.5px;color:var(--sub);flex-basis:100%}
.ans{border:1px solid var(--line);border-radius:14px;padding:12px 16px;margin-bottom:10px;background:#fff}
.ans[open] summary{margin-bottom:6px}
.alist{font-weight:700;margin:0;padding-left:1.8em}
.plist{margin:0;padding-left:1.6em}.plist li{margin-bottom:6px}
.source{font-size:13.5px;color:var(--sub);border-top:1px solid var(--line);padding-top:12px}
.pager{display:grid;gap:10px;margin-top:22px}
.pager a{display:block;border:1px solid var(--line);border-radius:14px;padding:10px 14px;text-decoration:none;font-weight:700}
.pager a span{display:block;font-size:13px;color:var(--sub)}
.pager .next{text-align:right}
@media (min-width:860px){.pager{grid-template-columns:1fr 1fr}.pager .next{grid-column:2}}

.ugroup{margin:10px 0 30px}
.ugroup h2{font-size:22px;margin:0 0 12px}.ugroup h2 span{color:var(--sub)}

/* フッター */
.foot{padding:34px 0 44px;border-top:1px solid var(--line);font-size:14px;color:var(--sub)}
.foot-in{display:grid;gap:12px}
.op{display:grid;grid-template-columns:auto 1fr;gap:2px 14px;margin:0}
.op dt{font-weight:700;color:var(--ink)}.op dd{margin:0}
.blank{color:#b3261e}
.foot nav{display:flex;gap:6px 18px;flex-wrap:wrap}
.foot p{margin:0}

/* 規約・ポリシー */
.legal-head{border-bottom:1px solid var(--line);padding:12px 20px}
.legal-logo img{height:40px;width:auto}
.legal{max-width:760px;margin:0 auto;padding:28px 20px 48px}
.legal h1{font-size:28px;margin:18px 0 4px}
.legal h2{font-size:19px;margin:32px 0 6px;padding-left:12px;border-left:5px solid var(--yellow)}
.legal h3{font-size:16.5px;margin:22px 0 4px}
.legal-meta{color:var(--sub);font-size:14px;margin:0 0 20px}
.draft-note{background:var(--yellow-soft);border-radius:12px;padding:10px 14px;font-size:14.5px;margin:0}
.tbd{display:inline-block;font-size:12.5px;background:#fdecea;color:#8c1d18;border-radius:6px;padding:0 8px;margin-left:6px;font-weight:700}
.legal-dl{display:grid;grid-template-columns:auto 1fr;gap:4px 16px}
.legal-dl dt{font-weight:700}.legal-dl dd{margin:0}
.legal-foot{border-top:1px solid var(--line);padding:20px;text-align:center;font-size:14px;color:var(--sub)}
.legal-foot nav{display:flex;gap:18px;justify-content:center;flex-wrap:wrap}
.qs:has(.one){list-style:none;padding-left:0}
@media (max-width:640px){
  .pcard a{flex-direction:row}
  .pfig{width:118px;flex:none;aspect-ratio:1;border-bottom:0;border-right:1px solid var(--line);padding:6px}
  .pbody{padding:10px 12px}
  .ptitle{font-size:16px}
  .pmeta{gap:8px}
}
.tagline{margin:0 0 14px;font-weight:700;font-size:16px;max-width:34em}
.week-head .kicker{margin:0}
.week-head h1{margin:2px 0 8px}
.hook{margin:6px 0 0;font-weight:700}
.phook{font-size:14px;color:var(--sub);line-height:1.6}
.pmeta{font-size:14px}
.swipe{display:inline-block;margin-left:8px;font-weight:700;color:var(--ink)}
@media (min-width:860px){.swipe{display:none}}
.filter{display:grid;gap:10px;margin:0 0 22px;padding:14px 16px;border:1px solid var(--line);border-radius:14px;background:#fff}
.filter fieldset{border:0;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.filter legend{float:left;font-weight:900;font-size:14px;margin-right:6px;min-width:3em}
.filter label{position:relative}
.filter input{position:absolute;opacity:0;inset:0}
.filter span{display:inline-flex;align-items:center;min-height:40px;padding:0 14px;border-radius:99px;border:1.5px solid var(--ink);font-weight:700;font-size:14.5px;cursor:pointer;background:#fff}
.filter input:checked+span{background:var(--ink);color:#fff}
.filter input:focus-visible+span{outline:3px solid #2a5fc4;outline-offset:2px}
.count{margin:0;font-weight:700;font-size:14px;color:var(--sub)}
.source,.crumb,.pdf span,.small{font-size:14px}
[hidden]{display:none!important}
/* 有料 (アプリ) の先生の解説: 表紙だけ・鍵 (2026-09-27) */
.vid.locked{position:relative;aspect-ratio:9/16}
.vid.locked img{width:100%;height:100%;object-fit:cover;filter:blur(3px) brightness(.55);display:block}
.vid.locked .lock{position:absolute;inset:0;margin:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:6px;color:#fff;text-align:center;padding:16px}
.vid.locked .lk{font-size:34px}.vid.locked b{font-size:17px;line-height:1.5}.vid.locked .lock span:last-child{font-size:13px;opacity:.85}
.vwho em{font-style:normal;font-size:12px;font-weight:700;border-radius:99px;padding:1px 9px}
.vwho em.free{background:var(--yellow-soft,#fff3c4);border:1px solid #d9b600}
.vwho em.paid{background:#eef1f6;border:1px solid #b8c0cc;color:#556}
/* YouTube は押すまで読み込まない (hp-build.py の video) */
.vid.yt .yt-play{position:relative;display:block;width:100%;aspect-ratio:9/16;padding:0;border:0;background:#000;cursor:pointer;color:#fff}
.vid.wide.yt .yt-play{aspect-ratio:16/9}
.yt-play img{width:100%;height:100%;object-fit:cover;display:block}
.yt-btn{position:absolute;left:50%;top:50%;width:76px;height:54px;margin:-27px 0 0 -38px;border-radius:14px;background:rgba(20,20,20,.78)}
.yt-btn::after{content:"";position:absolute;left:31px;top:15px;border-style:solid;border-width:12px 0 12px 20px;border-color:transparent transparent transparent #fff}
.yt-play:hover .yt-btn,.yt-play:focus-visible .yt-btn{background:#e62117}
.yt-note{position:absolute;left:0;right:0;bottom:0;padding:18px 10px 10px;font-size:13px;text-align:center;background:linear-gradient(transparent,rgba(0,0,0,.7))}
.week-head .kicker-row{margin:0}.week-head .posted{display:inline-block;margin-left:8px;font-size:12.5px;color:var(--sub)}