/* ==========================================================================
   CASE PAGE (case.html#<id>) and ABOUT PAGE (about.html)
   ========================================================================== */

/* ---------- case hero ---------- */
.cs-hero { padding-top: calc(120px + env(safe-area-inset-top, 0px)); padding-bottom: 40px; display: grid; gap: 22px; }
.back { justify-self: start; font-weight: 600; font-size: var(--t-small); text-decoration: none; color: var(--muted); }
.back:hover { color: var(--ink); }
.cs-kicker { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; letter-spacing: .05em; color: var(--muted); }
.cs-title { font-size: clamp(2.4rem, 5.6vw, 5.2rem); letter-spacing: -.05em; line-height: .98; max-width: 18ch; }
.cs-sub { font-size: var(--t-lead); color: var(--ink-2); max-width: 56ch; line-height: 1.45; }
.cs-facts { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); margin-top: 12px; border-top: 1.5px solid var(--ink); }
.cs-facts div { display: grid; align-content: start; gap: 4px; padding: 16px 20px 0 0; min-width: 0; }
.cs-facts dt { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; color: var(--muted); }
.cs-facts dd { font-weight: 600; }

.cs-cover { margin-top: 16px; }
.ev-hero .ev-frame { max-height: 78vh; }
.ev-hero .ev-frame img { max-height: calc(78vh - 30px); object-fit: contain; background: #fdf6ea; }
#main .cs-cover .ev-hero { max-width: 980px; margin-inline: auto; }
.cs-cover-type { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.cs-cover-type span { display: grid; align-content: end; gap: 8px; min-height: 240px; padding: 30px; border-radius: var(--r-xl); background: var(--ink); color: var(--bg); }
.cs-cover-type b { font-size: clamp(3rem, 6vw, 5rem); letter-spacing: -.05em; line-height: .9; }
.cs-cover-type small { color: color-mix(in srgb, var(--bg) 72%, transparent); font-size: 1rem; }

.cs-metrics { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; margin-top: 24px; }
.cs-metrics li { display: grid; gap: 6px; align-content: end; min-height: 180px; padding: 26px; border-radius: var(--r-xl); background: var(--bg-2); }
.cs-metrics li:first-child { background: var(--ink); color: var(--bg); }
.cs-metrics li:first-child .r-t { color: var(--hi); }
.r-v { font-size: clamp(2.6rem, 4.6vw, 4rem); font-weight: 800; letter-spacing: -.05em; line-height: .9; font-variant-numeric: tabular-nums; }
.r-l { font-weight: 600; }
.r-t { font-family: var(--f-mono); font-size: var(--t-label); color: var(--muted); }

.cs-platform { margin-top: 24px; padding: 26px; border-radius: var(--r-xl); border: 1.5px dashed var(--dim); display: grid; gap: 16px; }
.cs-platform-title { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; letter-spacing: .05em; color: var(--muted); }
.cs-platform ul { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
.cs-platform li { display: grid; gap: 2px; }
.cs-platform b { font-size: clamp(1.8rem, 3vw, 2.6rem); letter-spacing: -.04em; font-variant-numeric: tabular-nums; }
.cs-platform li span { color: var(--muted); font-weight: 500; }

/* ---------- case body: sticky chapter index + chapters ---------- */
.cs-layout { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: clamp(32px, 5vw, 80px); padding-block: clamp(64px, 10vh, 120px); align-items: start; }
.cs-index { position: sticky; top: 96px; }
.cs-index p { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; letter-spacing: .05em; color: var(--muted); margin-bottom: 12px; }
.cs-index ol { display: grid; gap: 2px; border-left: 1.5px solid var(--line); }
.cs-index a { display: grid; grid-template-columns: 28px 1fr; gap: 6px; padding: 7px 0 7px 14px; margin-left: -1.5px; border-left: 1.5px solid transparent; font-size: var(--t-small); color: var(--muted); text-decoration: none; line-height: 1.35; transition: color .2s, border-color .2s; }
.cs-index a span { font-family: var(--f-mono); font-size: .6875rem; padding-top: 2px; }
.cs-index a:hover, .cs-index a[aria-current] { color: var(--ink); border-left-color: var(--hi); }

.cs-main { min-width: 0; display: grid; gap: clamp(64px, 10vh, 112px); }
.cs-intro p { font-size: clamp(1.3rem, 2.1vw, 1.75rem); line-height: 1.4; letter-spacing: -.015em; font-weight: 500; max-width: 38ch; }
.cs-intro p + p { margin-top: 18px; color: var(--ink-2); font-weight: 400; font-size: clamp(1.125rem, 1.6vw, 1.35rem); }

.chapter { display: grid; gap: 20px; }
.chapter:focus { outline: none; }
.ch-head { display: grid; gap: 8px; padding-top: 22px; border-top: 1px solid var(--line); }
.ch-n { font-family: var(--f-mono); font-size: var(--t-label); color: var(--muted); }
.ch-head h2 { font-size: clamp(1.7rem, 3vw, 2.6rem); letter-spacing: -.04em; line-height: 1.05; }
.ch-meta { font-family: var(--f-mono); font-size: var(--t-small); color: var(--muted); }
.ch-body { display: grid; gap: 16px; max-width: 64ch; }
.ch-body p { font-size: 1.125rem; line-height: 1.65; color: var(--ink-2); }
.ch-side { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, .8fr); gap: clamp(24px, 4vw, 56px); align-items: start; }
.ch-side .figs { margin-top: 0; }
.ch-extra { display: grid; gap: 16px; margin-top: 16px; }
.ch-extra.is-side { grid-template-columns: minmax(0, 1fr) minmax(200px, 320px); align-items: center; gap: clamp(24px, 4vw, 56px); }
.ch-extra.is-side .figs { margin-top: 0; }
.ch-extra-text { font-size: 1.0625rem; line-height: 1.6; color: var(--ink-2); max-width: 60ch; }
.topic-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin-top: 6px; }
.topic-grid li { padding: 18px 20px; border-radius: var(--r-md); background: var(--bg-2); font-weight: 700; letter-spacing: -.01em; }
.callout { display: grid; gap: 6px; padding: 18px 22px; border-radius: var(--r-md); border-left: 3px solid var(--hi); background: var(--bg-2); font-size: var(--t-small); color: var(--ink-2); max-width: 72ch; }

/* ---------- diagrams ---------- */
.dg { margin: 8px 0 0; }
.dg figcaption { margin-top: 12px; font-size: var(--t-small); color: var(--muted); }
.dg-title { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; letter-spacing: .05em; color: var(--muted); margin-bottom: 12px; }

.dg-split { display: grid; justify-items: center; }
.dg-root { padding: 14px 22px; border-radius: 999px; background: var(--ink); color: var(--bg); font-weight: 700; text-align: center; }
.dg-branches { position: relative; width: 100%; display: grid; grid-template-columns: repeat(var(--n), minmax(0, 1fr)); gap: 14px; padding-top: 40px; }
.dg-branches::before { content: ""; position: absolute; top: 0; left: 50%; width: 1.5px; height: 20px; background: var(--ink); }
.dg-branches::after { content: ""; position: absolute; top: 20px; left: calc(100% / var(--n) / 2); right: calc(100% / var(--n) / 2); height: 1.5px; background: var(--ink); }
.dg-branches li { position: relative; display: grid; gap: 4px; padding: 18px; border-radius: var(--r-md); background: var(--bg-2); text-align: center; }
.dg-branches li::before { content: ""; position: absolute; top: -20px; left: 50%; width: 1.5px; height: 20px; background: var(--ink); }
.dg-branches b { font-size: 1.0625rem; }
.dg-branches span { font-size: var(--t-small); color: var(--muted); }

.dg-timeline ol { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 0; border-top: 1.5px solid var(--ink); }
.dg-timeline li { position: relative; display: grid; gap: 4px; padding: 22px 16px 6px 0; }
.dg-timeline li::before { content: ""; position: absolute; top: -6px; left: 0; width: 10px; height: 10px; border-radius: 50%; background: var(--bg); border: 2px solid var(--ink); }
.dg-timeline li:last-child::before { background: var(--hi); border-color: var(--hi); }
.tl-when { font-family: var(--f-mono); font-size: var(--t-small); color: var(--muted); }
.dg-timeline b { font-size: 1rem; line-height: 1.25; }
.tl-where { font-size: .8125rem; color: var(--muted); }

.dg-flow ol { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 10px; counter-reset: f; }
.dg-flow li { position: relative; display: grid; align-content: start; gap: 6px; padding: 16px; border-radius: var(--r-md); background: var(--bg-2); }
.dg-flow li b { font-size: .9375rem; }
.dg-flow li span { font-size: .8125rem; color: var(--muted); line-height: 1.45; }
.dg-flow li:not(:last-child)::after { content: "→"; position: absolute; right: -10px; top: 18px; width: 10px; text-align: center; color: var(--muted); font-size: .8125rem; }

.dg-steps ol { display: grid; gap: 0; counter-reset: s; border-left: 1.5px solid var(--ink); margin-left: 12px; }
.dg-steps li { counter-increment: s; position: relative; padding: 0 0 18px 30px; font-size: 1.0625rem; line-height: 1.5; color: var(--ink-2); max-width: 64ch; }
.dg-steps li::before { content: counter(s); position: absolute; left: -13px; top: -1px; width: 24px; height: 24px; border-radius: 50%; display: grid; place-items: center; background: var(--bg); border: 1.5px solid var(--ink); font: 600 .75rem/1 var(--f-mono); }
.dg-steps li:last-child { padding-bottom: 0; }

/* ---------- pager ---------- */
.cs-pager { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; padding-bottom: clamp(64px, 10vh, 120px); }
.cs-pager a { display: grid; gap: 8px; padding: 26px; border-radius: var(--r-lg); border: 1px solid var(--line); text-decoration: none; transition: transform .5s var(--ease), border-color .3s; }
.cs-pager a:hover { transform: translateY(-3px); border-color: var(--ink); }
.cs-pager span { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; color: var(--muted); }
.cs-pager b { font-size: 1.25rem; letter-spacing: -.02em; line-height: 1.2; }
.cs-pager .is-next { text-align: right; background: var(--bg-2); }

/* ---------- ABOUT ---------- */
.ab-hero { padding-top: calc(120px + env(safe-area-inset-top, 0px)); display: grid; gap: 28px; }
.ab-title { font-size: clamp(2.4rem, 5.6vw, 5.2rem); letter-spacing: -.05em; line-height: .98; max-width: 17ch; }
.ab-intro { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, .8fr); gap: clamp(32px, 6vw, 88px); align-items: start; }
.ab-copy { display: grid; gap: 18px; }
.ab-copy p { font-size: clamp(1.125rem, 1.6vw, 1.3rem); line-height: 1.6; color: var(--ink-2); max-width: 56ch; }
.ab-copy p:first-child { font-size: clamp(1.25rem, 1.9vw, 1.55rem); color: var(--ink); font-weight: 500; }
.ab-facts { border-top: 1.5px solid var(--ink); }
.ab-facts div { display: grid; gap: 4px; padding: 14px 0; border-bottom: 1px solid var(--line); }
.ab-facts dt { font-family: var(--f-mono); font-size: var(--t-label); text-transform: uppercase; color: var(--muted); }
.ab-facts dd { font-weight: 600; }
.exp-list { display: grid; }
.exp { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: clamp(20px, 4vw, 56px); padding-block: 32px; border-top: 1px solid var(--line); }
.exp-side { display: grid; gap: 4px; align-content: start; }
.exp-when { font-family: var(--f-mono); font-size: var(--t-small); }
.exp-where { font-size: var(--t-small); color: var(--muted); }
.exp-main { display: grid; gap: 14px; max-width: 70ch; }
.exp-main h3 { font-size: clamp(1.4rem, 2.4vw, 1.9rem); letter-spacing: -.03em; }
.exp-org { color: var(--muted); font-weight: 600; margin-top: -8px; }
.exp-main .arrow-link { justify-self: start; margin-top: 4px; font-size: .9375rem; }
.ab-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 48px clamp(32px, 6vw, 88px); padding-top: 0; }
.ab-wide { grid-column: 1 / -1; }
.ab-h { font-family: var(--f-mono); font-size: var(--t-label); font-weight: 500; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); padding-bottom: 14px; margin-bottom: 8px; border-bottom: 1.5px solid var(--ink); }
.ab-list li { display: grid; gap: 2px; padding-block: 12px; border-bottom: 1px solid var(--line); }
.ab-list b { font-size: 1.0625rem; }
.ab-list span { color: var(--muted); font-size: var(--t-small); }
.ab-skills { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 28px; margin-top: 12px; }
.ab-skills h3 { font-size: 1rem; margin-bottom: 12px; }

/* ---------- responsive ---------- */
@media (max-width: 1000px) {
  .cs-layout { grid-template-columns: 1fr; }
  .cs-index { position: static; }
  .cs-index ol { grid-template-columns: repeat(2, minmax(0, 1fr)); border-left: 0; gap: 0 16px; }
  .cs-index a { border-left: 0; padding-left: 0; margin-left: 0; border-bottom: 1px solid var(--line); }
  .dg-flow ol { grid-template-columns: 1fr; }
  .dg-flow li:not(:last-child)::after { content: "↓"; right: auto; left: 18px; top: auto; bottom: -16px; }
  .ab-skills { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 800px) {
  .cs-facts { grid-template-columns: 1fr 1fr; }
  .ch-side, .ch-extra.is-side, .ab-intro { grid-template-columns: 1fr; }
  .ch-extra.is-side .figs { max-width: 300px; }
  .ch-side .figs-side { max-width: 420px; }
  .cs-platform ul { grid-template-columns: 1fr 1fr; }
  .dg-branches { grid-template-columns: 1fr 1fr; }
  .dg-branches::after, .dg-branches li::before { display: none; }
  .exp { grid-template-columns: 1fr; gap: 10px; }
  .ab-grid { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .cs-index ol { grid-template-columns: 1fr; }
  .cs-cover-type { grid-template-columns: 1fr; }
  .cs-cover-type span { min-height: 140px; }
  .topic-grid, .dg-branches { grid-template-columns: 1fr; }
  .cs-pager { grid-template-columns: 1fr; }
  .cs-pager .is-next { text-align: left; }
  .ab-skills { grid-template-columns: 1fr; }
}