/* ==========================================================================
   STUDYBENCH, design system
   Metaphor: the ring binder (spine, tabs, dividers, sheets, index).
   Prefix: bnd-
   One sans family, two contrasted weights (400 / 800). Blue accent.
   No external request: system font stacks only.
   ========================================================================== */

/* --- Reset --- */
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
img,svg{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
ul,ol{list-style:none}
button{font:inherit;background:none;border:none;cursor:pointer}

/* --- Tokens --- */
:root{
  /* surfaces */
  --paper:#ffffff;
  --panel:#f4f6fa;
  --panel-deep:#eaeef6;
  --line:#e2e7f0;
  --line-strong:#cfd7e5;

  /* ink */
  --ink:#101828;
  --ink-soft:#3c4658;
  --ink-mute:#6b7688;
  --ink-faint:#8d97a8;

  /* accent */
  --tint:#155eef;
  --tint-deep:#0b3fae;
  --tint-wash:#e8effd;
  --tint-edge:#c6d8fb;

  /* type */
  --face:-apple-system,BlinkMacSystemFont,"Segoe UI Variable","Segoe UI","Helvetica Neue",Helvetica,Arial,"Liberation Sans",sans-serif;
  --w-plain:400;
  --w-heavy:800;

  /* geometry */
  --rad:12px;
  --rad-sm:8px;
  --rad-pill:999px;
  --desk:1200px;
  --gut:20px;

  /* elevation, three steps */
  --lift-1:0 1px 2px rgba(16,24,40,.05);
  --lift-2:0 6px 22px rgba(16,24,40,.07);
  --lift-3:0 20px 48px rgba(16,24,40,.11);

  --ease:.22s cubic-bezier(.2,.6,.2,1);
}

body{
  font-family:var(--face);
  font-weight:var(--w-plain);
  font-size:16px;
  line-height:1.65;
  color:var(--ink-soft);
  background:var(--paper);
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

h1,h2,h3,h4{
  font-family:var(--face);
  font-weight:var(--w-heavy);
  color:var(--ink);
  line-height:1.14;
  letter-spacing:-.02em;
}
h1{font-size:clamp(36px,5vw,60px)}
h2{font-size:clamp(28px,3.6vw,42px)}
h3{font-size:clamp(19px,2vw,23px);line-height:1.25}
h4{font-size:clamp(17px,1.6vw,19px);line-height:1.3}
strong,b{font-weight:var(--w-heavy);color:var(--ink)}

/* --- Frame --- */
.bnd-desk{width:100%;max-width:var(--desk);margin:0 auto;padding:0 var(--gut)}
@media(min-width:768px){.bnd-desk{padding:0 32px}}

.bnd-skip{
  position:absolute;left:-9999px;top:0;z-index:200;
  background:var(--tint);color:#fff;padding:12px 18px;border-radius:0 0 var(--rad) 0;
  font-weight:var(--w-heavy);
}
.bnd-skip:focus{left:0}

/* --- Spine (site header) --- */
.bnd-spine{
  position:sticky;top:0;z-index:100;
  background:rgba(255,255,255,.94);
  backdrop-filter:saturate(160%) blur(12px);
  border-bottom:1px solid var(--line);
}
.bnd-spine__inner{
  display:flex;align-items:center;justify-content:space-between;
  gap:18px;min-height:72px;flex-wrap:wrap;padding:12px 0;
}
.bnd-mark{display:flex;flex-direction:column;gap:2px}
.bnd-mark__name{
  font-size:21px;font-weight:var(--w-heavy);color:var(--ink);
  letter-spacing:-.03em;line-height:1;
}
.bnd-mark__name em{font-style:normal;color:var(--tint)}
.bnd-mark__line{
  font-size:11.5px;color:var(--ink-mute);letter-spacing:.09em;
  text-transform:uppercase;line-height:1.2;
}

.bnd-tabs{display:flex;flex-wrap:wrap;align-items:center;gap:2px}
.bnd-tab{
  display:inline-block;padding:8px 12px;border-radius:var(--rad-sm);
  font-size:14px;color:var(--ink-mute);white-space:nowrap;
  border-bottom:2px solid transparent;
  transition:color var(--ease),background var(--ease),border-color var(--ease);
}
.bnd-tab:hover{color:var(--ink);background:var(--panel)}
.bnd-tab--live{color:var(--tint);font-weight:var(--w-heavy);border-bottom-color:var(--tint)}
.bnd-tab--live:hover{color:var(--tint-deep);background:var(--tint-wash)}

/* --- Cover (hero) --- */
.bnd-cover{position:relative;isolation:isolate;overflow:hidden;background:#0b1524}
.bnd-cover__photo{
  position:absolute;inset:0;width:100%;height:100%;
  object-fit:cover;z-index:0;
}
.bnd-cover__glaze{
  position:absolute;inset:0;z-index:1;
  background:linear-gradient(180deg,rgba(7,17,36,.72) 0%,rgba(7,17,36,.62) 45%,rgba(7,17,36,.82) 100%);
}
.bnd-cover__inner{
  position:relative;z-index:2;
  padding:56px 0 44px;
}
@media(min-width:900px){.bnd-cover__inner{padding:44px 0 40px}}
.bnd-kicker{
  display:inline-flex;align-items:center;gap:10px;
  font-size:11.5px;font-weight:var(--w-heavy);letter-spacing:.16em;text-transform:uppercase;
  color:#bcd2ff;margin-bottom:12px;
}
.bnd-kicker::before{content:"";width:26px;height:2px;border-radius:2px;background:#4a86f7}
.bnd-cover__title{color:#fff;max-width:22ch;font-size:clamp(30px,3.4vw,42px)}
.bnd-cover__lede{
  margin-top:14px;max-width:72ch;font-size:clamp(15px,1.3vw,17px);
  color:rgba(255,255,255,.84);line-height:1.6;
}

.bnd-tally{
  display:grid;grid-template-columns:1fr;gap:10px;
  margin-top:20px;max-width:760px;
}
@media(min-width:640px){.bnd-tally{grid-template-columns:repeat(3,1fr);gap:12px}}
.bnd-tally__cell{
  background:rgba(255,255,255,.09);
  border:1px solid rgba(255,255,255,.18);
  border-radius:var(--rad);
  padding:10px 14px;
}
.bnd-tally__num{
  display:block;font-size:clamp(20px,2.2vw,24px);font-weight:var(--w-heavy);
  color:#fff;letter-spacing:-.02em;line-height:1.15;
}
.bnd-tally__word{
  display:block;margin-top:4px;font-size:12px;letter-spacing:.09em;
  text-transform:uppercase;color:rgba(255,255,255,.72);
}

/* Wide screens: the cover reads as a band, text left, tally rail right */
@media(min-width:1024px){
  .bnd-cover__inner{
    display:grid;grid-template-columns:minmax(0,1fr) 250px;
    column-gap:44px;align-items:center;padding:26px 0 22px;
  }
  .bnd-cover__inner .bnd-kicker{grid-column:1;grid-row:1;margin-bottom:10px}
  .bnd-cover__inner .bnd-cover__title{grid-column:1;grid-row:2}
  .bnd-cover__inner .bnd-cover__lede{grid-column:1;grid-row:3;margin-top:12px;max-width:66ch}
  .bnd-cover__inner .bnd-tally{
    grid-column:2;grid-row:1/4;grid-template-columns:1fr;gap:8px;
    margin-top:0;max-width:250px;align-self:center;
  }
  .bnd-cover__inner .bnd-tally__cell{padding:7px 13px}
}

/* --- Band (section) --- */
.bnd-band{padding:80px 0}
@media(min-width:900px){.bnd-band{padding:120px 0}}
.bnd-band--tint{background:var(--panel);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.bnd-band--tight{padding:64px 0}
@media(min-width:900px){.bnd-band--tight{padding:88px 0}}

.bnd-margin{
  display:inline-flex;align-items:center;gap:10px;
  font-size:11.5px;font-weight:var(--w-heavy);letter-spacing:.16em;
  text-transform:uppercase;color:var(--tint);margin-bottom:14px;
}
.bnd-margin::before{content:"";width:26px;height:2px;border-radius:2px;background:var(--tint)}

.bnd-band__head{margin-bottom:40px;max-width:720px}
@media(min-width:900px){.bnd-band__head{margin-bottom:56px}}

/* First band under the cover: keep the section grid on the first screen */
.bnd-cover + #bnd-main > .bnd-band:first-child{padding-top:24px}
.bnd-cover + #bnd-main > .bnd-band:first-child .bnd-divider__thumb{aspect-ratio:16/9}
.bnd-cover + #bnd-main > .bnd-band:first-child > .bnd-desk > .bnd-band__head{margin-bottom:20px;max-width:840px}
.bnd-cover + #bnd-main > .bnd-band:first-child > .bnd-desk > .bnd-band__head .bnd-margin{margin-bottom:10px}
.bnd-cover + #bnd-main > .bnd-band:first-child > .bnd-desk > .bnd-band__head h2{font-size:clamp(24px,2.4vw,30px)}
.bnd-cover + #bnd-main > .bnd-band:first-child > .bnd-desk > .bnd-band__head .bnd-band__note{margin-top:8px;font-size:15.5px;max-width:78ch}
.bnd-band__note{margin-top:14px;font-size:17px;color:var(--ink-mute);max-width:62ch}
.bnd-band__row{
  display:flex;align-items:flex-end;justify-content:space-between;
  gap:24px;flex-wrap:wrap;margin-bottom:40px;
}
.bnd-band__row .bnd-band__head{margin-bottom:0}

/* --- Ring (link button) --- */
.bnd-ring{
  display:inline-flex;align-items:center;gap:8px;
  padding:12px 20px;border-radius:var(--rad);
  font-size:14px;font-weight:var(--w-heavy);
  background:var(--tint);color:#fff;
  box-shadow:var(--lift-1);
  transition:background var(--ease),transform var(--ease),box-shadow var(--ease);
}
.bnd-ring:hover{background:var(--tint-deep);transform:translateY(-1px);box-shadow:var(--lift-2)}
.bnd-ring--quiet{
  background:var(--paper);color:var(--ink);border:1px solid var(--line-strong);box-shadow:none;
}
.bnd-ring--quiet:hover{background:var(--panel);color:var(--tint);border-color:var(--tint-edge)}
.bnd-ring::after{content:"\2192";font-weight:var(--w-heavy);transition:transform var(--ease)}
.bnd-ring:hover::after{transform:translateX(3px)}

/* --- Dividers (category grid) --- */
.bnd-dividers{display:grid;grid-template-columns:1fr;gap:22px}
@media(min-width:640px){.bnd-dividers{grid-template-columns:repeat(2,1fr)}}
@media(min-width:1024px){.bnd-dividers{grid-template-columns:repeat(3,1fr)}}

.bnd-divider{
  display:flex;flex-direction:column;
  background:var(--paper);border:1px solid var(--line);border-radius:var(--rad);
  overflow:hidden;box-shadow:var(--lift-1);
  transition:transform var(--ease),box-shadow var(--ease),border-color var(--ease);
}
.bnd-divider:hover{transform:translateY(-3px);box-shadow:var(--lift-3);border-color:var(--tint-edge)}
.bnd-divider__thumb{
  width:100%;aspect-ratio:16/10;object-fit:cover;background:var(--panel-deep);
}
.bnd-divider__body{padding:22px 22px 24px;display:flex;flex-direction:column;flex:1}
.bnd-divider__title{margin-bottom:10px}
.bnd-divider__title a{transition:color var(--ease)}
.bnd-divider__title a:hover{color:var(--tint)}
.bnd-divider__text{font-size:14.5px;color:var(--ink-mute);flex:1}
.bnd-divider__go{
  margin-top:18px;font-size:13px;font-weight:var(--w-heavy);color:var(--tint);
  display:inline-flex;align-items:center;gap:6px;transition:gap var(--ease);
}
.bnd-divider__go::after{content:"\2192"}
.bnd-divider:hover .bnd-divider__go{gap:10px}

/* --- Sheets (article feed) --- */
.bnd-sheets{display:grid;grid-template-columns:1fr;gap:24px}
@media(min-width:640px){.bnd-sheets{grid-template-columns:repeat(2,1fr)}}
@media(min-width:1024px){.bnd-sheets{grid-template-columns:repeat(3,1fr);gap:28px}}

.bnd-sheet{
  display:flex;flex-direction:column;
  background:var(--paper);border:1px solid var(--line);border-radius:var(--rad);
  overflow:hidden;box-shadow:var(--lift-1);
  transition:transform var(--ease),box-shadow var(--ease),border-color var(--ease);
}
.bnd-sheet:hover{transform:translateY(-3px);box-shadow:var(--lift-3);border-color:var(--tint-edge)}
.bnd-sheet__thumb{width:100%;aspect-ratio:16/10;object-fit:cover;background:var(--panel-deep)}
.bnd-sheet__body{padding:20px 20px 22px;display:flex;flex-direction:column;flex:1}
.bnd-sheet__meta{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:12px}
.bnd-sheet__clip{
  display:inline-block;padding:4px 10px;border-radius:var(--rad-pill);
  background:var(--tint-wash);border:1px solid var(--tint-edge);
  font-size:11px;font-weight:var(--w-heavy);letter-spacing:.07em;text-transform:uppercase;
  color:var(--tint-deep);
}
.bnd-sheet__stamp{
  font-size:12.5px;color:var(--ink-faint);letter-spacing:.02em;
  font-variant-numeric:tabular-nums;
}
.bnd-sheet__title{margin-bottom:9px}
.bnd-sheet__title a{transition:color var(--ease)}
.bnd-sheet__title a:hover{color:var(--tint)}
.bnd-sheet__lede{font-size:14.5px;color:var(--ink-mute);flex:1}

/* wide variant, used on category listings */
.bnd-sheets--roll{grid-template-columns:1fr;gap:18px}
@media(min-width:1024px){.bnd-sheets--roll{grid-template-columns:1fr;gap:18px}}
.bnd-sheet--wide{flex-direction:column}
@media(min-width:720px){
  .bnd-sheet--wide{flex-direction:row;align-items:stretch}
  .bnd-sheet--wide .bnd-sheet__thumb{width:300px;flex:0 0 300px;height:auto;aspect-ratio:16/10}
  .bnd-sheet--wide .bnd-sheet__body{padding:24px 26px}
}

/* --- Slip (breadcrumb) --- */
.bnd-slip{
  display:flex;flex-wrap:wrap;align-items:center;gap:8px;
  font-size:13px;color:var(--ink-faint);
}
.bnd-slip a{transition:color var(--ease)}
.bnd-slip a:hover{color:var(--tint)}
.bnd-slip li::after{content:"/";margin-left:8px;color:var(--line-strong)}
.bnd-slip li:last-child::after{content:""}
.bnd-slip li:last-child{color:var(--ink-soft);font-weight:var(--w-heavy)}

/* --- Leaf (page header block) --- */
.bnd-leaf{
  background:var(--panel);border-bottom:1px solid var(--line);
  padding:28px 0 56px;
}
@media(min-width:900px){.bnd-leaf{padding:32px 0 72px}}
.bnd-leaf__head{margin-top:26px;max-width:820px}
.bnd-leaf__stand{
  margin-top:18px;font-size:clamp(16px,1.7vw,19px);color:var(--ink-soft);
  line-height:1.7;max-width:64ch;
}
.bnd-leaf__meta{
  display:flex;flex-wrap:wrap;align-items:center;gap:10px;
  margin-top:24px;font-size:13px;color:var(--ink-mute);
}
.bnd-leaf__meta .bnd-sheet__clip{margin-right:2px}
.bnd-leaf__dot{width:4px;height:4px;border-radius:50%;background:var(--line-strong)}

/* --- Prose (article body) --- */
.bnd-prose{max-width:720px;margin:0 auto}
.bnd-prose > * + *{margin-top:22px}
.bnd-prose h2{margin-top:52px;font-size:clamp(24px,2.8vw,32px)}
.bnd-prose h3{margin-top:38px}
.bnd-prose p{font-size:17px;line-height:1.75;color:var(--ink-soft)}
.bnd-prose a{color:var(--tint);font-weight:var(--w-heavy);border-bottom:1px solid var(--tint-edge)}
.bnd-prose a:hover{color:var(--tint-deep);border-bottom-color:var(--tint-deep)}
.bnd-prose ul,.bnd-prose ol{padding-left:0;display:grid;gap:12px}
.bnd-prose li{
  position:relative;padding-left:26px;font-size:17px;line-height:1.7;color:var(--ink-soft);
}
.bnd-prose ul li::before{
  content:"";position:absolute;left:6px;top:11px;width:7px;height:7px;
  border-radius:2px;background:var(--tint);
}
.bnd-prose ol{counter-reset:bnd-count}
.bnd-prose ol li{counter-increment:bnd-count;padding-left:34px}
.bnd-prose ol li::before{
  content:counter(bnd-count);position:absolute;left:0;top:2px;
  width:22px;height:22px;border-radius:var(--rad-sm);
  background:var(--tint-wash);border:1px solid var(--tint-edge);color:var(--tint-deep);
  font-size:12px;font-weight:var(--w-heavy);display:flex;align-items:center;justify-content:center;
}

.bnd-plate{margin:44px auto;max-width:860px}
.bnd-plate__img{
  width:100%;aspect-ratio:16/10;object-fit:cover;
  border-radius:var(--rad);border:1px solid var(--line);box-shadow:var(--lift-2);
  background:var(--panel-deep);
}
.bnd-plate__cap{
  margin-top:12px;font-size:13px;color:var(--ink-faint);line-height:1.6;text-align:left;
}

.bnd-recall{
  margin:44px auto;max-width:720px;
  background:var(--panel);border:1px solid var(--line);border-left:3px solid var(--tint);
  border-radius:var(--rad);padding:24px 26px;
}
.bnd-recall__head{
  font-size:11.5px;font-weight:var(--w-heavy);letter-spacing:.14em;text-transform:uppercase;
  color:var(--tint-deep);margin-bottom:12px;
}
.bnd-recall p{font-size:16px;color:var(--ink-soft)}
.bnd-recall ul{margin-top:12px;display:grid;gap:10px}
.bnd-recall li{position:relative;padding-left:22px;font-size:15.5px;color:var(--ink-soft)}
.bnd-recall li::before{
  content:"";position:absolute;left:4px;top:9px;width:6px;height:6px;border-radius:2px;background:var(--tint);
}

/* --- Crossrefs (internal links block) --- */
.bnd-crossrefs{
  max-width:720px;margin:56px auto 0;padding-top:32px;border-top:1px solid var(--line);
}
.bnd-crossrefs__head{
  font-size:11.5px;font-weight:var(--w-heavy);letter-spacing:.14em;text-transform:uppercase;
  color:var(--ink-mute);margin-bottom:18px;
}
.bnd-crossref{
  display:flex;align-items:center;justify-content:space-between;gap:16px;
  padding:14px 16px;border:1px solid var(--line);border-radius:var(--rad);
  background:var(--paper);margin-bottom:10px;
  transition:border-color var(--ease),background var(--ease),transform var(--ease);
}
.bnd-crossref:hover{border-color:var(--tint-edge);background:var(--panel);transform:translateX(2px)}
.bnd-crossref__title{font-size:15px;font-weight:var(--w-heavy);color:var(--ink)}
.bnd-crossref__stamp{font-size:12.5px;color:var(--ink-faint);white-space:nowrap;font-variant-numeric:tabular-nums}

/* --- Index (footer) --- */
.bnd-index{background:#0b1524;color:rgba(255,255,255,.72);padding:64px 0 0}
.bnd-index__grid{
  display:grid;grid-template-columns:1fr;gap:36px;padding-bottom:48px;
}
@media(min-width:720px){.bnd-index__grid{grid-template-columns:1.4fr 1fr 1fr}}
@media(min-width:1024px){.bnd-index__grid{grid-template-columns:1.6fr 1fr 1fr 1fr;gap:44px}}
.bnd-index__name{
  font-size:20px;font-weight:var(--w-heavy);color:#fff;letter-spacing:-.03em;margin-bottom:12px;
}
.bnd-index__name em{font-style:normal;color:#6f9ffb}
.bnd-index__blurb{font-size:14.5px;line-height:1.7;color:rgba(255,255,255,.62);max-width:38ch}
.bnd-index__head{
  font-size:11.5px;font-weight:var(--w-heavy);letter-spacing:.14em;text-transform:uppercase;
  color:#fff;margin-bottom:16px;
}
.bnd-index__list{display:grid;gap:10px}
.bnd-index__list a{font-size:14.5px;color:rgba(255,255,255,.7);transition:color var(--ease)}
.bnd-index__list a:hover{color:#fff}
.bnd-index__base{
  border-top:1px solid rgba(255,255,255,.12);padding:20px 0 28px;
  display:flex;flex-wrap:wrap;gap:12px;justify-content:space-between;
  font-size:13px;color:rgba(255,255,255,.5);
}
.bnd-index__base a:hover{color:#fff}

/* --- Focus states --- */
a:focus-visible,button:focus-visible{
  outline:2px solid var(--tint);outline-offset:3px;border-radius:4px;
}

@media(prefers-reduced-motion:reduce){
  *{transition:none!important;animation:none!important;scroll-behavior:auto!important}
}