/* Grace Portfolio · shared case-study shell
   One implementation of the parts every case study shares:
   top bar (back + language), chapter rail, footer navigation.
   Each project keeps its own type and colour; the shell only reads
   html[data-gx-tone="light" | "dark"] to pick a neutral palette.
   Visual language follows shadcn/ui (neutral base). */

:root{
  --gx-font: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  --gx-radius: 8px;
  --gx-bar-h: 56px;
  --gx-ease: cubic-bezier(.2, .8, .2, 1);
}
html[data-gx-tone="light"],.gx-foot[data-gx-tone="light"]{
  --gx-bar-bg: rgba(255, 255, 255, .82);
  --gx-fg: #0a0a0a;
  --gx-muted: #737373;
  --gx-border: #e5e5e5;
  --gx-accent: #f5f5f5;
  --gx-seg-bg: #f5f5f5;
  --gx-seg-on: #ffffff;
  --gx-seg-on-fg: #0a0a0a;
  --gx-seg-shadow: 0 1px 2px rgba(0, 0, 0, .08), 0 0 0 1px rgba(0, 0, 0, .04);
  --gx-rail-idle: #d4d4d4;
  --gx-rail-hover: #737373;
  --gx-rail-on: #0a0a0a;
  --gx-tip-bg: #0a0a0a;
  --gx-tip-fg: #fafafa;
  --gx-ring: #a3a3a3;
}
html[data-gx-tone="dark"],.gx-foot[data-gx-tone="dark"]{
  --gx-bar-bg: rgba(10, 10, 10, .78);
  --gx-fg: #fafafa;
  --gx-muted: #a3a3a3;
  --gx-border: rgba(255, 255, 255, .12);
  --gx-accent: rgba(255, 255, 255, .08);
  --gx-seg-bg: rgba(255, 255, 255, .08);
  --gx-seg-on: #fafafa;
  --gx-seg-on-fg: #0a0a0a;
  --gx-seg-shadow: 0 1px 2px rgba(0, 0, 0, .3);
  --gx-rail-idle: #525252;
  --gx-rail-hover: #a3a3a3;
  --gx-rail-on: #fafafa;
  --gx-tip-bg: #fafafa;
  --gx-tip-fg: #0a0a0a;
  --gx-ring: #737373;
}

.gx-icon{width:18px;height:18px;flex:none;display:block;fill:currentColor}

/* ---------- Top bar ---------- */
.gx-bar{
  position:sticky;top:0;z-index:600;
  height:calc(var(--gx-bar-h) + env(safe-area-inset-top, 0px));
  padding:env(safe-area-inset-top, 0px) max(16px, env(safe-area-inset-right, 0px)) 0 max(16px, env(safe-area-inset-left, 0px));
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  background:var(--gx-bar-bg);
  border-bottom:1px solid var(--gx-border);
  -webkit-backdrop-filter:saturate(1.6) blur(14px);backdrop-filter:saturate(1.6) blur(14px);
  font:500 13px/1 var(--gx-font);color:var(--gx-fg);
  transition:background-color .2s ease, border-color .2s ease, color .2s ease;
  box-sizing:border-box;
}
.gx-bar *{box-sizing:border-box}
.gx-bar-start{display:flex;align-items:center;gap:6px;min-width:0}
.gx-back{
  display:inline-flex;align-items:center;gap:6px;height:32px;padding:0 10px 0 8px;margin-left:-8px;
  border-radius:var(--gx-radius);color:inherit;text-decoration:none;white-space:nowrap;
  transition:background-color .15s ease;
}
.gx-back:hover{background:var(--gx-accent)}
.gx-back .gx-icon{transition:transform .2s var(--gx-ease)}
.gx-back:hover .gx-icon{transform:translateX(-2px)}
.gx-crumb{display:flex;align-items:center;gap:10px;min-width:0;color:var(--gx-muted);white-space:nowrap}
.gx-crumb::before{content:"";width:1px;height:16px;background:var(--gx-border)}
.gx-crumb b{font-weight:500;color:var(--gx-fg);overflow:hidden;text-overflow:ellipsis}
.gx-crumb span{font-variant-numeric:tabular-nums}

/* Language: segmented control, identical on every case study */
.gx-lang{display:inline-flex;align-items:center;gap:2px;height:32px;padding:3px;border-radius:var(--gx-radius);background:var(--gx-seg-bg);flex:none}
.gx-lang button{
  appearance:none;border:0;margin:0;cursor:pointer;
  height:26px;padding:0 10px;border-radius:calc(var(--gx-radius) - 2px);
  background:transparent;color:var(--gx-muted);
  font:500 12.5px/1 var(--gx-font);white-space:nowrap;
  transition:background-color .15s ease, color .15s ease, box-shadow .15s ease;
}
.gx-lang button:hover{color:var(--gx-fg)}
.gx-lang button[aria-pressed="true"]{background:var(--gx-seg-on);color:var(--gx-seg-on-fg);box-shadow:var(--gx-seg-shadow)}

.gx-back:focus-visible,.gx-lang button:focus-visible,.gx-rail-btn:focus-visible,.gx-foot a:focus-visible{outline:2px solid var(--gx-ring);outline-offset:2px}

/* ---------- Chapter rail ----------
   One tick per section. The current tick fills as you read through it.
   Hover (mouse) opens a panel with every section name. */
.gx-rail{
  position:fixed;z-index:590;top:50%;right:clamp(6px, 1.6vw, 24px);transform:translateY(-50%);
  display:flex;flex-direction:column;align-items:flex-end;
}
.gx-rail-list{
  padding:6px 0;border-radius:12px;border:1px solid transparent;
  display:flex;flex-direction:column;align-items:stretch;
  transition:background-color .18s ease, border-color .18s ease, box-shadow .18s ease, padding .18s var(--gx-ease);
}
.gx-rail-btn{
  appearance:none;border:0;margin:0;background:transparent;cursor:pointer;flex:none;
  min-width:40px;height:30px;padding:0 4px 0 0;border-radius:6px;
  display:flex;align-items:center;justify-content:flex-end;gap:14px;
  font:500 13px/1 var(--gx-font);color:var(--gx-muted);white-space:nowrap;text-align:left;
}
.gx-rail-label{display:none;flex:1}
.gx-rail-label i{font-style:normal;font-variant-numeric:tabular-nums;opacity:.6;margin-right:10px}
.gx-rail-line{position:relative;display:block;flex:none;width:16px;height:2px;border-radius:2px;overflow:hidden;background:var(--gx-rail-idle);transition:width .18s ease, background-color .18s ease}
.gx-rail-fill{position:absolute;inset:0;background:var(--gx-rail-on);transform-origin:left;transform:scaleX(0)}
.gx-rail-btn.is-done .gx-rail-line{background:var(--gx-rail-hover)}
.gx-rail-btn.is-current .gx-rail-line{width:28px}
.gx-rail-btn.is-current .gx-rail-fill{transform:scaleX(var(--gx-p, 0))}
@media (hover:hover) and (pointer:fine){
  .gx-rail-btn:hover .gx-rail-line{width:24px;background:var(--gx-rail-hover)}
  .gx-rail-btn.is-current:hover .gx-rail-line{width:28px;background:var(--gx-rail-idle)}
  .gx-rail:hover .gx-rail-list,.gx-rail:focus-within .gx-rail-list{
    padding:8px 10px 8px 14px;background:var(--gx-bar-bg);border-color:var(--gx-border);
    -webkit-backdrop-filter:saturate(1.6) blur(14px);backdrop-filter:saturate(1.6) blur(14px);
    box-shadow:0 8px 28px rgba(0, 0, 0, .12);
  }
  .gx-rail:hover .gx-rail-label,.gx-rail:focus-within .gx-rail-label{display:block}
  .gx-rail-btn:hover,.gx-rail-btn.is-current{color:var(--gx-fg)}
}
.gx-rail-tip{
  position:absolute;right:calc(100% + 10px);top:0;transform:translateY(-50%);
  padding:6px 10px;border-radius:6px;pointer-events:none;white-space:nowrap;
  background:var(--gx-tip-bg);color:var(--gx-tip-fg);
  font:500 12px/1.2 var(--gx-font);
  box-shadow:0 4px 16px rgba(0, 0, 0, .14);
}
.gx-rail-tip[hidden]{display:none!important}

/* ---------- Footer navigation ---------- */
.gx-foot{
  display:grid;grid-template-columns:1fr 1fr;gap:12px;
  padding:40px max(20px, 5vw) calc(40px + env(safe-area-inset-bottom, 0px));
  border-top:1px solid var(--gx-border);
  font:500 13px/1.3 var(--gx-font);color:var(--gx-fg);
  box-sizing:border-box;
}
.gx-foot a{
  display:flex;flex-direction:column;gap:8px;padding:18px 20px;
  border:1px solid var(--gx-border);border-radius:12px;
  background:var(--gx-accent);color:var(--gx-fg);text-decoration:none;
  transition:background-color .15s ease, border-color .15s ease;
}
.gx-foot small{display:flex;align-items:center;gap:6px;color:var(--gx-muted);font-size:12px;font-weight:500}
.gx-foot strong{color:var(--gx-fg);font-size:16px;font-weight:600;letter-spacing:-.01em}
.gx-foot .gx-next{text-align:right;align-items:flex-end}
.gx-foot .gx-icon{width:16px;height:16px;transition:transform .15s ease-out}
@media (hover:hover) and (pointer:fine){
  .gx-foot a:hover{background:var(--gx-seg-bg);border-color:color-mix(in srgb,var(--gx-fg) 22%,transparent)}
  .gx-foot a:hover small .gx-icon{transform:translateX(-2px)}
  .gx-foot a.gx-next:hover small .gx-icon{transform:translateX(2px)}
}

@media (max-width: 720px){
  .gx-crumb{display:none}
  .gx-rail{right:2px}
  .gx-rail-btn{min-width:28px;height:28px}
  .gx-rail-line{width:10px}
  .gx-rail-btn.is-current .gx-rail-line{width:18px}
  .gx-rail-tip{font-size:11px;right:calc(100% + 6px)}
  .gx-foot{grid-template-columns:1fr;padding-inline:16px}
}
@media (max-width: 380px){
  .gx-back span{display:none}
}
@media (prefers-reduced-motion: reduce){
  .gx-bar,.gx-back,.gx-back .gx-icon,.gx-lang button,.gx-rail-line,.gx-rail-list,.gx-foot a{transition:none}
}
@media print{.gx-bar,.gx-rail{display:none}}

/* ---------- Shared case-study motion (gx-motion.js) ---------- */
html.gx-motion .gx-rv{opacity:0;transform:translateY(14px)}
html.gx-motion .gx-rv.gx-in{opacity:1;transform:none;transition:opacity .5s ease-out var(--gx-d,0ms),transform .6s cubic-bezier(.16,1,.3,1) var(--gx-d,0ms)}
html.gx-motion .gx-bx{clip-path:inset(0 100% 0 0)}
html.gx-motion .gx-by{clip-path:inset(100% 0 0 0)}
html.gx-motion .gx-wp{clip-path:inset(0 100% 0 0)}
html.gx-motion .gx-bx.gx-in,html.gx-motion .gx-by.gx-in{clip-path:inset(0 0 0 0);transition:clip-path .8s cubic-bezier(.65,0,.35,1) calc(var(--gx-d,0ms) + 150ms)}
html.gx-motion .gx-wp.gx-in{clip-path:inset(0 0 0 0);transition:clip-path 1s cubic-bezier(.65,0,.35,1) .1s}
@media (prefers-reduced-motion: reduce){html.gx-motion .gx-rv,html.gx-motion .gx-bx,html.gx-motion .gx-by,html.gx-motion .gx-wp{opacity:1;transform:none;clip-path:none}}
@media print{html.gx-motion .gx-rv,html.gx-motion .gx-bx,html.gx-motion .gx-by,html.gx-motion .gx-wp{opacity:1;transform:none;clip-path:none}}