:root{
  --bg:#f7fbff;--paper:#fff;--ink:#17324d;--muted:#61758a;
  --line:rgba(23,50,77,.12);--shadow:0 14px 34px rgba(23,50,77,.11);
  --soft:0 7px 18px rgba(23,50,77,.08);--accent:#377dff;
  --accent2:#7d5cff;--accent-soft:#eaf2ff;--max:1180px
}
*{box-sizing:border-box}html{scroll-behavior:smooth}
body{margin:0;min-height:100vh;color:var(--ink);background:
 radial-gradient(circle at 8% 7%,rgba(255,255,255,.95) 0 3%,transparent 3.4%),
 linear-gradient(180deg,#eff9ff 0%,var(--bg) 46%,#fffdf7 100%);
 font-family:"Trebuchet MS","Segoe UI",system-ui,-apple-system,BlinkMacSystemFont,
 "Noto Sans",Arial,sans-serif;line-height:1.55}
body.grade-a{--accent:#ff7b54;--accent2:#ffba45;--accent-soft:#fff1e8}
body.grade-b{--accent:#2f80ed;--accent2:#56ccf2;--accent-soft:#eaf6ff}
body.grade-g{--accent:#8f5ee8;--accent2:#c06cff;--accent-soft:#f3ebff}
body.grade-d{--accent:#13a37b;--accent2:#5bcf92;--accent-soft:#e8faf3}
body.grade-e{--accent:#e69d00;--accent2:#ffd15c;--accent-soft:#fff6d9}
body.grade-st{--accent:#db4c73;--accent2:#ff7ba1;--accent-soft:#ffedf3}
a{color:inherit}a:focus-visible,button:focus-visible,input:focus-visible,
summary:focus-visible{outline:4px solid rgba(22,43,255,.34);outline-offset:3px}
.skip-link{position:fixed;z-index:999;top:10px;left:10px;transform:translateY(-150%);
 padding:10px 14px;border-radius:12px;background:#111;color:#fff;text-decoration:none}
.skip-link:focus{transform:none}.site-shell{width:min(calc(100% - 28px),var(--max));margin:auto}
.topbar{position:sticky;z-index:30;top:0;border-bottom:1px solid rgba(23,50,77,.08);
 background:rgba(255,255,255,.9);backdrop-filter:blur(13px)}
.topbar-inner{min-height:68px;display:flex;align-items:center;justify-content:space-between;gap:14px}
.brand{display:inline-flex;align-items:center;gap:10px;font-weight:900;text-decoration:none}
.brand-mark{display:grid;width:42px;height:42px;place-items:center;border-radius:14px;
 background:linear-gradient(135deg,var(--accent),var(--accent2));box-shadow:var(--soft);
 color:#fff;font-size:22px}.top-actions{display:flex;gap:8px;flex-wrap:wrap}
.nav-pill,.action-btn{min-height:44px;display:inline-flex;align-items:center;justify-content:center;
 gap:7px;padding:9px 14px;border:1px solid var(--line);border-radius:999px;background:#fff;
 color:var(--ink);font:inherit;font-weight:800;text-decoration:none;cursor:pointer}
.nav-pill:hover,.action-btn:hover{transform:translateY(-1px)}
.hero{position:relative;overflow:hidden;margin-top:28px;padding:clamp(28px,5vw,58px);
 border-radius:28px;background:linear-gradient(135deg,var(--accent),var(--accent2));
 color:#fff;box-shadow:var(--shadow)}
.hero:after{content:"✦  ✧  ✦";position:absolute;right:4%;bottom:5%;
 font-size:clamp(38px,7vw,90px);opacity:.17;transform:rotate(-8deg)}
.hero-row{position:relative;z-index:1;display:flex;align-items:center;gap:24px}
.hero-emoji{flex:none;font-size:clamp(58px,9vw,112px);filter:drop-shadow(0 10px 18px rgba(0,0,0,.12))}
.hero-kicker{margin:0 0 7px;font-size:.92rem;font-weight:900;letter-spacing:.09em;text-transform:uppercase}
.hero h1{max-width:850px;margin:0;font-size:clamp(2rem,5vw,4.15rem);line-height:1.03;letter-spacing:-.045em}
.hero p{max-width:760px;margin:16px 0 0;font-size:clamp(1rem,2vw,1.25rem);font-weight:650}
.section-heading{margin:42px 0 18px}.section-heading h2{margin:0;font-size:clamp(1.45rem,3vw,2rem)}
.section-heading p{margin:5px 0 0;color:var(--muted);font-weight:650}
.grade-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;padding-bottom:24px}
.grade-card{position:relative;min-height:225px;display:flex;flex-direction:column;justify-content:space-between;
 overflow:hidden;padding:24px;border:1px solid var(--line);border-radius:28px;background:#fff;
 text-decoration:none;box-shadow:var(--soft);transition:.18s}
.grade-card:hover,.book-card:hover{transform:translateY(-5px);box-shadow:var(--shadow)}
.grade-card .emoji{font-size:48px}.grade-card .big-letter{position:absolute;right:16px;top:4px;
 color:var(--card,var(--accent));font-size:86px;font-weight:950;opacity:.24}
.grade-card h3{margin:16px 0 4px;font-size:1.5rem}.grade-card p{margin:0;color:var(--muted);font-weight:650}
.grade-card .go{display:inline-flex;margin-top:18px;color:var(--card,var(--accent));font-weight:900}
.book-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;margin:28px 0 44px}
.book-card{display:block;min-height:235px;padding:26px;border:1px solid var(--line);border-radius:28px;
 background:#fff;text-decoration:none;box-shadow:var(--soft);transition:.18s}
.book-card .book-icon{font-size:47px}.book-card h2{margin:14px 0 6px;font-size:1.65rem}
.book-card p{margin:0;color:var(--muted);font-weight:650}.book-cta{display:inline-flex;margin-top:18px;
 color:var(--accent);font-weight:900}.breadcrumbs{display:flex;align-items:center;gap:8px;flex-wrap:wrap;
 margin:24px 0 0;color:var(--muted);font-size:.95rem;font-weight:750}.breadcrumbs a{text-decoration:none}
.book-toolbar{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:12px;align-items:center;margin:24px 0 22px}
.search-wrap{position:relative}.search-wrap:before{content:"🔎";position:absolute;left:16px;top:50%;transform:translateY(-50%)}
.search-input{width:100%;min-height:54px;padding:12px 18px 12px 48px;border:2px solid var(--line);
 border-radius:18px;background:#fff;color:var(--ink);font:inherit;font-size:1rem;box-shadow:var(--soft)}
.search-input:focus{border-color:var(--accent)}.toolbar-actions{display:flex;gap:8px;flex-wrap:wrap}
.book-links{display:flex;gap:10px;flex-wrap:wrap;margin-top:19px}.primary-link{min-height:48px;
 display:inline-flex;align-items:center;gap:9px;padding:10px 17px;border-radius:16px;background:#fff;
 color:var(--accent);font-weight:900;text-decoration:none;box-shadow:var(--soft)}
.unit-list{display:grid;gap:16px;margin:0 0 48px}.unit{overflow:clip;border:1px solid var(--line);
 border-radius:28px;background:rgba(255,255,255,.96);box-shadow:var(--soft)}
.unit>summary{position:relative;cursor:pointer;list-style:none;padding:21px 58px 21px 22px;
 background:linear-gradient(90deg,var(--accent-soft),rgba(255,255,255,.85));font-size:1.12rem;font-weight:900}
.unit>summary::-webkit-details-marker,.topic>summary::-webkit-details-marker,
.subtopic>summary::-webkit-details-marker{display:none}
.unit>summary:after,.topic>summary:after,.subtopic>summary:after{content:"＋";position:absolute;right:20px;top:50%;
 transform:translateY(-50%);font-weight:900;color:var(--accent)}
.unit[open]>summary:after,.topic[open]>summary:after,.subtopic[open]>summary:after{content:"−"}
.unit-body{padding:16px}.topic-list{display:grid;gap:11px}.topic{border:1px solid var(--line);
 border-radius:20px;background:#fff}.topic>summary{position:relative;cursor:pointer;list-style:none;
 padding:16px 52px 16px 18px;font-weight:850}.topic>summary:hover{background:var(--accent-soft)}
.topic-body{padding:2px 16px 17px}.subtopic-list{display:grid;gap:9px;margin-top:12px}
.subtopic{border:1px dashed rgba(23,50,77,.22);border-radius:14px;background:#fff}
.subtopic>summary{position:relative;cursor:pointer;list-style:none;padding:13px 48px 13px 14px;font-weight:800}
.subtopic-body{padding:0 14px 14px}.resource-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));
 gap:9px;margin-top:9px}.resource-card{min-height:60px;display:grid;grid-template-columns:38px minmax(0,1fr) 22px;
 gap:10px;align-items:center;padding:10px 12px;border:1px solid var(--line);border-radius:15px;
 background:#fbfdff;text-decoration:none;transition:.15s}
.resource-card:hover{transform:translateY(-2px);background:var(--accent-soft)}
.resource-icon{display:grid;width:38px;height:38px;place-items:center;border-radius:12px;background:#fff;
 font-size:20px;box-shadow:0 3px 9px rgba(23,50,77,.08)}
.resource-title{font-weight:750;overflow-wrap:anywhere}.resource-meta{display:block;margin-top:2px;
 color:var(--muted);font-size:.78rem;font-weight:700}.external-arrow{color:var(--accent);font-weight:950}
.note-box{margin:9px 0;padding:10px 12px;border-left:4px solid var(--accent);border-radius:10px;
 background:var(--accent-soft);color:var(--muted);font-size:.93rem;font-weight:650}
.empty-note{margin:8px 0 0;padding:12px;border-radius:12px;background:#fff8e6;color:#795800;font-weight:750}
.search-status{min-height:24px;margin:-8px 0 14px;color:var(--muted);font-size:.92rem;font-weight:750}
.no-results{display:none;margin:18px 0 44px;padding:22px;border:2px dashed var(--line);border-radius:20px;
 background:#fff;text-align:center;color:var(--muted);font-weight:800}.footer{margin-top:48px;padding:26px 0 34px;
 border-top:1px solid var(--line);color:var(--muted);font-size:.92rem}.footer-inner{display:grid;grid-template-columns:minmax(0,1fr) auto minmax(0,1fr);align-items:center;gap:18px}.footer-ai-credit{text-align:center}.footer-inner>span:last-child{text-align:right}.footer a{color:var(--accent);font-weight:800}
.home-note{margin:24px 0 44px;padding:19px 21px;border:1px solid var(--line);border-radius:20px;
 background:rgba(255,255,255,.88);color:var(--muted);font-weight:650}.is-hidden{display:none!important}
@media(max-width:850px){.grade-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
 .resource-grid{grid-template-columns:1fr}.book-toolbar{grid-template-columns:1fr}}
@media(max-width:620px){.site-shell{width:min(calc(100% - 18px),var(--max))}.brand-text{display:none}
 .hero{margin-top:16px;padding:26px 20px}.hero-row{align-items:flex-start;gap:12px}.hero-emoji{font-size:48px}
 .grade-grid,.book-grid{grid-template-columns:1fr}.grade-card{min-height:190px}.unit-body{padding:10px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;transition:none!important}}


/* book-image-hero + photo-banner update 2026-09-25 */
.hero-book-image-wrap{width:180px;flex:0 0 180px;display:flex;align-items:center;justify-content:center}
.hero-book-image{display:block;width:100%;height:auto;max-height:190px;object-fit:contain;border-radius:18px;border:4px solid rgba(255,255,255,.72);box-shadow:0 10px 24px rgba(25,38,72,.20)}
.hero-photo-banner{padding:0!important;background:transparent!important;box-shadow:none!important;overflow:hidden;border-radius:28px}
.hero-photo-banner img{display:block;width:100%;height:auto;margin:0;border:0;border-radius:28px}
.sr-only{position:absolute!important;width:1px!important;height:1px!important;padding:0!important;margin:-1px!important;overflow:hidden!important;clip:rect(0,0,0,0)!important;white-space:nowrap!important;border:0!important}
@media(max-width:700px){.hero-book-image-wrap{width:130px;flex-basis:130px}.hero-book-image{max-height:140px;border-radius:14px}}

/* banner-v4-original-ratio: untouched source images, full site-shell width */
.hero-photo-banner{display:block;width:100%;max-width:100%;margin:20px 0 0;padding:0!important;background:transparent!important;box-shadow:none!important;overflow:visible;border-radius:24px}
.hero-photo-banner img{display:block;width:100%!important;max-width:100%!important;height:auto!important;margin:0!important;border:0!important;border-radius:24px;object-fit:fill!important;object-position:center!important;filter:none!important}
@media(max-width:760px){.footer-inner{grid-template-columns:1fr;text-align:center}.footer-ai-credit,.footer-inner>span:last-child{text-align:center}}

/* banner-v5-sizing: 54% top banners, original aspect ratio, no crop */
.hero-photo-banner{
  width:54%!important;
  max-width:54%!important;
  margin:20px auto 0!important;
  padding:0!important;
  background:transparent!important;
  box-shadow:none!important;
  overflow:visible!important;
  border-radius:24px!important;
}
.hero-photo-banner img{
  display:block!important;
  width:100%!important;
  max-width:100%!important;
  height:auto!important;
  margin:0!important;
  border:0!important;
  border-radius:24px!important;
  object-fit:contain!important;
  object-position:center!important;
  filter:none!important;
}
@media(max-width:760px){.hero-photo-banner{width:100%!important;max-width:100%!important}}

/* banner-v6-fix: ALL 9 top banners span the full site-shell width, original ratio, no crop */
.hero-photo-banner{
  display:block!important;
  width:100%!important;
  max-width:100%!important;
  margin:20px 0 0!important;
  padding:0!important;
  background:transparent!important;
  box-shadow:none!important;
  overflow:visible!important;
  border-radius:24px!important;
}
.hero-photo-banner img{
  display:block!important;
  width:100%!important;
  max-width:100%!important;
  height:auto!important;
  margin:0!important;
  border:0!important;
  border-radius:24px!important;
  object-fit:contain!important;
  object-position:center!important;
  filter:none!important;
}

/* banner-v6-fix: keep compact book banner dimensions, enlarge book image to 90% of colored hero height */
body[class^="grade-"] .hero:not(.hero-photo-banner){
  position:relative!important;
  overflow:hidden!important;
}
body[class^="grade-"] .hero:not(.hero-photo-banner) .hero-row{
  padding-left:170px!important;
}
body[class^="grade-"] .hero:not(.hero-photo-banner) .hero-book-image-wrap{
  position:absolute!important;
  left:24px!important;
  top:5%!important;
  width:150px!important;
  height:90%!important;
  flex:none!important;
  display:flex!important;
  align-items:center!important;
  justify-content:center!important;
  margin:0!important;
  padding:0!important;
}
body[class^="grade-"] .hero:not(.hero-photo-banner) .hero-book-image{
  display:block!important;
  width:auto!important;
  height:100%!important;
  max-width:100%!important;
  max-height:none!important;
  object-fit:contain!important;
  box-sizing:border-box!important;
  margin:0!important;
}
@media(max-width:760px){
  body[class^="grade-"] .hero:not(.hero-photo-banner) .hero-row{padding-left:122px!important}
  body[class^="grade-"] .hero:not(.hero-photo-banner) .hero-book-image-wrap{
    left:16px!important;
    width:104px!important;
    height:90%!important;
    top:5%!important;
  }
}


/* deployment-v7-cache-marker */