/* ============ Tokens ============ */
:root{
  --ink: #1B2129;
  --ink-soft: #2A3240;
  --paper: #EEF0EA;
  --paper-card: #FCFCFA;
  --text: #1B2129;
  --text-soft: #5B6270;
  --line: #DADCD3;

  --band: #E7E9DE;
  --band-line: #fcf7f7;

  --physics: #35659E;
  --chemistry: #C06430;
  --biology: #3E7A4C;
  --math: #6C4C9B;
  --social: #A9822F;
  --english: #A03A56;
  --featured: #8A8264;

  --reading: #2C8C86;
  --games: #C0587A;
  --mathscience: #3E7A4C;
  --videos: #C4622D;

  --pre-accent: #2C8C86;
  --higher-accent: #35659E;

  --radius: 14px;
  --font-display: "Fraunces", Georgia, serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
}

*{ box-sizing: border-box; }
html{ scroll-behavior: smooth; }

body{
  margin:0;
  background: var(--paper);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a{ color: inherit; }

/* ============ Hero ============ */
.hero{
  background: var(--band);
  color: var(--text);
  padding: 72px 24px 56px;
  border-bottom: 1px solid var(--band-line);
}
.hero-inner{
  max-width: 780px;
  margin: 0 auto;
}
.back-link{
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--text-soft);
  text-decoration: none;
  margin-bottom: 22px;
  border-bottom: 1px solid transparent;
}
.back-link:hover{ color: var(--text); border-color: var(--text); }

.eyebrow{
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-soft);
  margin: 0 0 18px;
}
.hero h1{
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(2.4rem, 6vw, 3.6rem);
  line-height: 1.05;
  margin: 0 0 20px;
  letter-spacing: -0.01em;
  color: var(--text);
}
.hero-sub{
  font-size: 1.05rem;
  color: var(--text-soft);
  max-width: 58ch;
  margin: 0 0 28px;
}
.hero-meta{
  font-size: 14px;
  color: var(--text-soft);
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  align-items: center;
}
.hero-meta strong{
  color: var(--text);
  font-family: var(--font-mono);
  font-weight: 500;
}
.hero-meta .dot{ opacity: .5; }

/* ============ Search ============ */
.search-bar-wrap{
  background: var(--band);
  padding: 0 24px 40px;
  padding-top: 20px;
}
.search-bar{
  max-width: 780px;
  margin: 0 auto;
  background: var(--paper-card);
  border: 1px solid var(--band-line);
  border-radius: 999px;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 20px;
  
  box-shadow: 0 1px 3px rgba(27,33,41,.05);
}
.search-icon{
  width: 18px; height: 18px;
  color: var(--text-soft);
  flex-shrink: 0;
}
.search-bar input{
  flex: 1;
  background: none;
  border: none;
  outline: none;
  color: var(--text);
  font-family: var(--font-body);
  font-size: 15px;
}
.search-bar input::placeholder{ color: #92968A; }

/* ============ Tabs (binder-tab nav) ============ */
.tabs{
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  gap: 4px;
  padding: 14px 20px 0;
  background: var(--paper);
  overflow-x: auto;
  scrollbar-width: none;
  border-bottom: 1px solid var(--line);
}
.tabs::-webkit-scrollbar{ display:none; }

.tab{
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: .01em;
  text-decoration: none;
  color: var(--text-soft);
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-bottom: none;
  padding: 10px 18px 12px;
  border-radius: 10px 10px 0 0;
  clip-path: polygon(10px 0, 100% 0, 100% 100%, 0 100%, 0 10px);
  transition: transform .15s ease, color .15s ease, background .15s ease;
  position: relative;
  top: 1px;
}
.tab:hover{ transform: translateY(-2px); }

.tab-featured{ --c: var(--featured); }
.tab-physics{ --c: var(--physics); }
.tab-chemistry{ --c: var(--chemistry); }
.tab-biology{ --c: var(--biology); }
.tab-math{ --c: var(--math); }
.tab-social{ --c: var(--social); }
.tab-english{ --c: var(--english); }
.tab-reading{ --c: var(--reading); }
.tab-games{ --c: var(--games); }
.tab-mathscience{ --c: var(--mathscience); }
.tab-videos{ --c: var(--videos); }

.tab{ border-top: 3px solid var(--c); }
.tab.active{
  color: #fff;
  background: var(--c);
  border-color: var(--c);
}

/* ============ Shelves / sections ============ */
main{ max-width: 1080px; margin: 0 auto; padding: 0 20px; }

.shelf{ padding: 56px 0 8px; scroll-margin-top: 74px; }
.shelf-head{ margin-bottom: 28px; }
.shelf-head h2{
  font-family: var(--font-display);
  font-size: 1.9rem;
  font-weight: 600;
  margin: 0 0 8px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.shelf-head p{
  margin: 0;
  color: var(--text-soft);
  max-width: 60ch;
}
.tab-dot{
  width: 12px; height: 12px;
  border-radius: 3px;
  background: var(--c);
  display: inline-block;
}
.shelf-physics .tab-dot{ --c: var(--physics); }
.shelf-chemistry .tab-dot{ --c: var(--chemistry); }
.shelf-biology .tab-dot{ --c: var(--biology); }
.shelf-math .tab-dot{ --c: var(--math); }
.shelf-social .tab-dot{ --c: var(--social); }
.shelf-english .tab-dot{ --c: var(--english); }
.shelf-reading .tab-dot{ --c: var(--reading); }
.shelf-games .tab-dot{ --c: var(--games); }
.shelf-mathscience .tab-dot{ --c: var(--mathscience); }
.shelf-videos .tab-dot{ --c: var(--videos); }

.shelf-featured .shelf-head h2::before{
  content: "";
  width: 12px; height: 12px;
  border-radius: 3px;
  background: var(--featured);
  display: inline-block;
}

/* ============ Cards ============ */
.grid{
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 16px;
  padding-bottom: 8px;
}

.card{
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-left: 4px solid var(--featured);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: box-shadow .18s ease, transform .18s ease;
}
.shelf-physics .card{ border-left-color: var(--physics); }
.shelf-chemistry .card{ border-left-color: var(--chemistry); }
.shelf-biology .card{ border-left-color: var(--biology); }
.shelf-math .card{ border-left-color: var(--math); }
.shelf-social .card{ border-left-color: var(--social); }
.shelf-english .card{ border-left-color: var(--english); }
.shelf-reading .card{ border-left-color: var(--reading); }
.shelf-games .card{ border-left-color: var(--games); }
.shelf-mathscience .card{ border-left-color: var(--mathscience); }
.shelf-videos .card{ border-left-color: var(--videos); }

.card:hover{
  box-shadow: 0 8px 24px rgba(27,33,41,.08);
  transform: translateY(-2px);
}

.card-top{ display:flex; }
.badge{
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .03em;
  color: var(--text-soft);
  background: var(--paper);
  border: 1px solid var(--line);
  padding: 4px 9px;
  border-radius: 999px;
}

.card h3{
  font-family: var(--font-display);
  font-size: 1.22rem;
  font-weight: 600;
  margin: 0;
}
.card p{
  margin: 0;
  color: var(--text-soft);
  font-size: 14.5px;
  flex: 1;
}

.card-link{
  margin-top: 4px;
  align-self: flex-start;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  color: var(--text);
  border-bottom: 1.5px solid var(--text);
  padding-bottom: 2px;
}
.card-link svg{ width: 14px; height: 14px; }
.card-link:hover{ color: var(--physics); border-color: var(--physics); }
.shelf-chemistry .card-link:hover{ color: var(--chemistry); border-color: var(--chemistry); }
.shelf-biology .card-link:hover{ color: var(--biology); border-color: var(--biology); }
.shelf-math .card-link:hover{ color: var(--math); border-color: var(--math); }
.shelf-social .card-link:hover{ color: var(--social); border-color: var(--social); }
.shelf-english .card-link:hover{ color: var(--english); border-color: var(--english); }
.shelf-reading .card-link:hover{ color: var(--reading); border-color: var(--reading); }
.shelf-games .card-link:hover{ color: var(--games); border-color: var(--games); }
.shelf-mathscience .card-link:hover{ color: var(--mathscience); border-color: var(--mathscience); }
.shelf-videos .card-link:hover{ color: var(--videos); border-color: var(--videos); }

/* ============ No results ============ */
.no-results{
  text-align: center;
  color: var(--text-soft);
  padding: 60px 0;
  font-size: 15px;
}

/* ============ Footer ============ */
.site-footer{
  margin-top: 60px;
  padding: 36px 20px 48px;
  text-align: center;
  border-top: 1px solid var(--line);
  color: var(--text-soft);
  font-size: 14px;
}
.site-footer p{ margin: 4px 0; }
.footer-fine{ font-family: var(--font-mono); font-size: 12px; opacity: .8; }

/* ============ Motion & focus ============ */
a:focus-visible, input:focus-visible{
  outline: 2px solid var(--physics);
  outline-offset: 2px;
}
@media (prefers-reduced-motion: reduce){
  *{ transition: none !important; scroll-behavior: auto !important; }
}

/* ============ Responsive ============ */
@media (max-width: 640px){
  .hero{ padding: 52px 20px 40px; }
  .shelf{ padding: 40px 0 4px; }
  .grid{ grid-template-columns: 1fr; }
}

/* ============ Chooser landing page ============ */
.chooser-body{
  background: var(--paper);
}
.chooser-page{
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 64px 24px;
  max-width: 1000px;
  margin: 0 auto;
}
.chooser-intro{
  text-align: center;
  max-width: 620px;
  margin-bottom: 48px;
}
.chooser-intro .eyebrow{ justify-content: center; display: flex; }
.chooser-title{
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(2.2rem, 6vw, 3.2rem);
  color: var(--text);
  margin: 0 0 16px;
  letter-spacing: -0.01em;
}
.chooser-sub{
  color: var(--text-soft);
  font-size: 1.05rem;
  margin: 0;
}

.chooser-grid{
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
  width: 100%;
}

.chooser-card{
  --c: var(--pre-accent);
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 14px;
  text-decoration: none;
  color: var(--text);
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-top: 4px solid var(--c);
  border-radius: var(--radius);
  padding: 36px 30px 30px;
  min-height: 260px;
  box-shadow: 0 1px 3px rgba(27,33,41,.04);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}
.chooser-card:hover{
  transform: translateY(-4px);
  box-shadow: 0 16px 36px rgba(27,33,41,.12);
  border-color: var(--line);
}
.chooser-higher{ --c: var(--higher-accent); }

.chooser-tag{
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--c);
  background: var(--paper);
  border: 1px solid var(--line);
  padding: 4px 10px;
  border-radius: 999px;
  align-self: flex-start;
}
.chooser-card h2{
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.9rem;
  line-height: 1.1;
  margin: 0;
  color: var(--text);
}
.chooser-card p{
  margin: 0;
  color: var(--text-soft);
  font-size: 15px;
  flex: 1;
}
.chooser-enter{
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
  font-size: 14.5px;
  color: var(--c);
}
.chooser-enter svg{ width: 15px; height: 15px; transition: transform .18s ease; }
.chooser-card:hover .chooser-enter svg{ transform: translate(2px,-2px); }

.chooser-footnote{
  margin-top: 40px;
  color: var(--text-soft);
  font-size: 13px;
  text-align: center;
}

@media (max-width: 640px){
  .chooser-grid{ grid-template-columns: 1fr; }
  .chooser-card{ min-height: 200px; padding: 28px 24px 24px; }
}