.yk-root {
  --yk-bg:     var(--paper);
  --yk-bg2:    var(--paper-2);
  --yk-ink:    var(--ink);
  --yk-muted:  var(--ink-soft);
  --yk-faint:  var(--silver-2, color-mix(in srgb, var(--ink) 34%, var(--paper)));
  --yk-accent: var(--navy);
  --yk-accent2:var(--silver, var(--navy));
  --yk-line:   color-mix(in srgb, var(--ink) 14%, transparent);
  --yk-sans:   var(--sans);
  --yk-disp:   var(--display);
  --yk-panel-w: clamp(20rem, 78vw, 46rem);
  background: var(--yk-bg); color: var(--yk-ink); font-family: var(--yk-sans);
  line-height: 1.8; -webkit-font-smoothing: antialiased;
}
.yk-root *, .yk-root *::before, .yk-root *::after { box-sizing: border-box; }
.yk-root ::selection { background: var(--yk-accent); color: var(--yk-bg); }
.yk-root img { max-width: 100%; height: auto; display: block; }

.yk-head { position: fixed; top: 0; left: 0; right: 0; z-index: 70; display: flex; align-items: center; justify-content: space-between;
  padding: .9rem clamp(1.1rem,4vw,2.6rem);
  background: linear-gradient(180deg, color-mix(in srgb, var(--yk-bg) 92%, transparent), color-mix(in srgb, var(--yk-bg) 55%, transparent) 60%, transparent);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px); }
.yk-brand { font-family: var(--yk-disp); font-weight: 800; font-size: 1.05rem; letter-spacing: .04em; display: flex; align-items: center; gap: .55rem; }
.yk-brand .yk-dot { width: .5rem; height: .5rem; border-radius: 50%; background: var(--yk-accent); box-shadow: 0 0 10px var(--yk-accent); }
.yk-brand b { color: var(--yk-accent); font-weight: 800; }
.yk-nav { display: flex; gap: .15rem; align-items: center; }
.yk-nav a { display: none; min-height: 44px; align-items: center; padding: 0 .85rem; text-decoration: none; font-size: .84rem;
  color: var(--yk-muted); transition: color .18s; font-family: var(--yk-disp); letter-spacing: .04em; cursor: pointer; }
.yk-nav a:hover { color: var(--yk-ink); }
.yk-cta { display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: 0 1.25rem;
  background: var(--yk-accent); color: var(--yk-bg); border-radius: 40px; text-decoration: none; font-weight: 700; font-size: .88rem;
  letter-spacing: .02em; border: none; cursor: pointer; font-family: var(--yk-sans); transition: transform .15s, box-shadow .2s; }
.yk-cta:hover { transform: translateY(-1px); box-shadow: 0 6px 22px color-mix(in srgb, var(--yk-accent) 28%, transparent); }
.yk-cta--ghost { background: transparent; color: var(--yk-ink); border: 1px solid var(--yk-line); }
.yk-cta--ghost:hover { border-color: var(--yk-accent); box-shadow: none; transform: none; }
@media (min-width: 860px) { .yk-nav a { display: inline-flex; } }

.yk-track { display: flex; height: 100vh; height: 100svh; overflow-x: auto; overflow-y: hidden;
  scroll-snap-type: x mandatory; scroll-behavior: smooth; -webkit-overflow-scrolling: touch; scrollbar-width: none; }
.yk-track::-webkit-scrollbar { display: none; }
.yk-panel { flex: 0 0 auto; height: 100vh; height: 100svh; width: var(--yk-panel-w);
  scroll-snap-align: start; position: relative; overflow: hidden;
  display: flex; flex-direction: column; justify-content: center;
  padding: clamp(5rem,11vh,7.5rem) clamp(1.6rem,4.5vw,4.5rem) clamp(3.5rem,9vh,5.5rem);
  border-right: 1px solid var(--yk-line); background: var(--yk-bg); }

.yk-chapter { position: absolute; top: clamp(4.2rem,9vh,6rem); left: clamp(1.6rem,4.5vw,4.5rem);
  font-family: var(--yk-disp); font-weight: 800; line-height: .8; font-size: clamp(4.5rem,3rem + 7vw,9rem);
  color: transparent; -webkit-text-stroke: 1px var(--yk-faint); letter-spacing: -.03em;
  pointer-events: none; user-select: none; z-index: 0; opacity: .55; }
.yk-chapter--solid { -webkit-text-stroke: 0; color: var(--yk-faint); opacity: .18; }

.yk-spine { position: absolute; top: 0; right: 0; height: 100%; width: clamp(2.4rem,4vw,3.2rem);
  display: flex; align-items: center; justify-content: center; border-left: 1px solid var(--yk-line); z-index: 1; pointer-events: none; }
.yk-spine span { writing-mode: vertical-rl; font-family: var(--yk-disp); font-size: .72rem; letter-spacing: .34em;
  text-transform: uppercase; color: var(--yk-faint); }
.yk-panel > * { position: relative; z-index: 2; }

.yk-intro { width: min(94%,40rem); }
.yk-eyebrow { font-family: var(--yk-disp); font-size: .78rem; letter-spacing: .24em; color: var(--yk-accent);
  text-transform: uppercase; margin-bottom: 1.3rem; display: flex; align-items: center; gap: .7rem; }
.yk-eyebrow::before { content: ""; width: 2rem; height: 1px; background: var(--yk-accent); }
.yk-intro h1 { font-family: var(--yk-disp); font-weight: 800; font-size: clamp(2.7rem,1.8rem + 6vw,6.2rem);
  line-height: .96; letter-spacing: -.015em; text-wrap: balance; }
.yk-intro h1 em { font-style: normal; color: var(--yk-accent); }
.yk-intro p { margin-top: 1.7rem; max-width: 40ch; color: var(--yk-muted); text-wrap: pretty; }
.yk-intro .yk-actions { margin-top: 2.3rem; display: flex; flex-wrap: wrap; gap: .8rem; }
.yk-scrollcue { margin-top: 2.6rem; display: flex; align-items: center; gap: .6rem; color: var(--yk-faint);
  font-family: var(--yk-disp); font-size: .74rem; letter-spacing: .18em; text-transform: uppercase; }
.yk-scrollcue .yk-arrow { display: inline-block; animation: ykSlide 1.6s ease-in-out infinite; }
@keyframes ykSlide { 0%,100% { transform: translateX(0); } 50% { transform: translateX(6px); } }

.yk-panel--gallery { width: auto; padding-right: 0; }
.yk-rail { display: flex; align-items: center; gap: clamp(1rem,2vw,1.8rem); height: 100%; padding-right: clamp(1.6rem,4.5vw,4.5rem); }
.yk-rail__head { flex: 0 0 auto; width: min(70vw,16rem); padding-right: 1rem; }
.yk-rail__head h2 { font-family: var(--yk-disp); font-weight: 800; font-size: clamp(1.8rem,1.3rem+2.4vw,3rem); line-height: 1.04; text-wrap: balance; }
.yk-rail__head p { margin-top: 1rem; color: var(--yk-muted); text-wrap: pretty; font-size: .95rem; }
.yk-work { flex: 0 0 auto; width: clamp(15rem,30vw,21rem); }
.yk-work--wide { width: clamp(20rem,42vw,30rem); }
.yk-ph { width: 100%; border-radius: 8px; overflow: hidden; position: relative; aspect-ratio: 3/4;
  background: radial-gradient(120% 80% at 30% 0%, color-mix(in srgb, var(--yk-ink) 14%, var(--yk-bg2)) 0%, var(--yk-bg2) 45%, var(--yk-bg) 100%);
  box-shadow: 0 18px 40px rgba(0,0,0,.45); }
.yk-work--wide .yk-ph { aspect-ratio: 4/3; }
.yk-ph > img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.yk-ph::before { content: ""; position: absolute; inset: 0; opacity: .5; z-index: 1;
  background-image: repeating-linear-gradient(135deg, rgba(255,255,255,.025) 0 2px, transparent 2px 9px); }
.yk-ph__num { position: absolute; top: 0; left: 0; font-family: var(--yk-disp); font-weight: 800;
  font-size: .72rem; letter-spacing: .12em; background: var(--yk-accent); color: var(--yk-bg); padding: .32rem .6rem; margin: .7rem; border-radius: 3px; z-index: 3; }
.yk-scrim { position: absolute; inset: 0; background: linear-gradient(180deg, transparent 38%, rgba(0,0,0,.55) 78%, rgba(0,0,0,.82)); z-index: 2; }
.yk-work__cap { position: absolute; left: 0; right: 0; bottom: 0; z-index: 3; padding: clamp(1rem,2.4vw,1.5rem); color: #fff; }
.yk-work__cap .yk-no { font-family: var(--yk-disp); font-size: .76rem; letter-spacing: .14em; color: var(--yk-accent); text-shadow: 0 1px 6px rgba(0,0,0,.7); }
.yk-work__cap h3 { font-family: var(--yk-disp); font-weight: 800; font-size: clamp(1.25rem,1.05rem+1.1vw,1.7rem);
  margin-top: .25rem; line-height: 1.1; text-shadow: 0 2px 16px rgba(0,0,0,.75); text-wrap: balance; }
.yk-work__cap p { font-size: .9rem; color: #ece9e2; margin-top: .2rem; text-shadow: 0 1px 10px rgba(0,0,0,.85); text-wrap: pretty; }
.yk-rail__more { flex: 0 0 auto; width: min(60vw,12rem); display: flex; flex-direction: column; justify-content: center; align-items: flex-start; gap: 1rem; padding-left: .5rem; }
.yk-rail__more p { color: var(--yk-muted); font-size: .92rem; text-wrap: pretty; }

.yk-text { width: min(94%,38rem); }
.yk-text .yk-eyebrow { color: var(--yk-accent2); }
.yk-text .yk-eyebrow::before { background: var(--yk-accent2); }
.yk-text h2 { font-family: var(--yk-disp); font-weight: 800; font-size: clamp(1.9rem,1.3rem+3vw,3.4rem); line-height: 1.06; text-wrap: balance; letter-spacing: -.01em; }
.yk-text > p { margin-top: 1.5rem; color: var(--yk-muted); max-width: 44ch; text-wrap: pretty; }
.yk-features { display: flex; gap: clamp(1.2rem,3vw,2.4rem); margin-top: 2.4rem; flex-wrap: wrap; }
.yk-feat { flex: 1 1 12rem; min-width: 11rem; max-width: 16rem; padding-top: 1.1rem; border-top: 1px solid var(--yk-line); }
.yk-feat .yk-fnum { font-family: var(--yk-disp); font-weight: 800; font-size: .9rem; color: var(--yk-accent); letter-spacing: .1em; }
.yk-feat h4 { font-family: var(--yk-disp); font-weight: 600; font-size: 1.1rem; margin-top: .5rem; line-height: 1.3; text-wrap: balance; }
.yk-feat p { margin-top: .5rem; color: var(--yk-muted); font-size: .92rem; line-height: 1.75; text-wrap: pretty; }

.yk-quote { width: min(94%,40rem); }
.yk-quote .yk-eyebrow { color: var(--yk-accent2); }
.yk-quote .yk-eyebrow::before { background: var(--yk-accent2); }
.yk-quote blockquote { font-family: var(--yk-disp); font-weight: 500; font-size: clamp(1.4rem,1.1rem+1.8vw,2.4rem); line-height: 1.45; text-wrap: balance;
  padding-left: 1.6rem; border-left: 3px solid var(--yk-accent); }
.yk-quote blockquote .yk-jp { font-family: var(--yk-sans); }
.yk-quote cite { display: block; margin-top: 1.4rem; padding-left: 1.6rem; font-style: normal; color: var(--yk-muted); font-size: .92rem; }
.yk-quote cite b { color: var(--yk-ink); font-weight: 500; }
.yk-voices { display: flex; gap: 1rem; margin-top: 2.2rem; flex-wrap: wrap; }
.yk-voice { flex: 1 1 13rem; min-width: 12rem; max-width: 18rem; background: var(--yk-bg2); border: 1px solid var(--yk-line); border-radius: 12px; padding: 1.2rem 1.3rem; }
.yk-voice p { font-size: .92rem; color: var(--yk-ink); line-height: 1.75; text-wrap: pretty; }
.yk-voice cite { display: block; margin-top: .9rem; padding: 0; font-style: normal; color: var(--yk-muted); font-size: .82rem; }
.yk-stars { color: var(--yk-accent2); letter-spacing: .1em; font-size: .85rem; margin-bottom: .6rem; }

.yk-end { width: min(94%,40rem); }
.yk-end h2 { font-family: var(--yk-disp); font-weight: 800; font-size: clamp(1.9rem,1.3rem+3vw,3.4rem); line-height: 1.06; text-wrap: balance; letter-spacing: -.01em; }
.yk-end > p { margin-top: 1.2rem; color: var(--yk-muted); max-width: 42ch; text-wrap: pretty; }
.yk-actions--end { display: flex; flex-wrap: wrap; gap: .8rem; margin-top: 1.9rem; }
.yk-foot { margin-top: 2.4rem; padding-top: 1.6rem; border-top: 1px solid var(--yk-line); color: var(--yk-muted); font-size: .84rem; line-height: 1.95; }
.yk-foot a { text-decoration: none; color: var(--yk-muted); cursor: pointer; }
.yk-foot a:hover { color: var(--yk-accent); }
.yk-foot .yk-fbrand { font-family: var(--yk-disp); font-weight: 800; color: var(--yk-ink); letter-spacing: .03em; }

.yk-index { position: fixed; bottom: 1.4rem; left: 50%; transform: translateX(-50%); z-index: 65;
  display: flex; gap: .85rem; align-items: center; background: color-mix(in srgb, var(--yk-bg2) 78%, transparent); backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px); padding: .55rem .95rem; border-radius: 40px; border: 1px solid var(--yk-line); box-shadow: 0 10px 30px rgba(0,0,0,.4); }
.yk-index__pos { font-family: var(--yk-disp); font-weight: 600; font-size: .74rem; letter-spacing: .12em; color: var(--yk-ink); white-space: nowrap; }
.yk-index__pos b { color: var(--yk-accent); }
.yk-frames { display: flex; gap: .4rem; align-items: center; }
.yk-frames button { width: .62rem; height: .62rem; padding: 0; border: none; border-radius: 2px; background: var(--yk-faint); cursor: pointer; transition: background .2s, transform .2s, width .25s; flex: 0 0 auto; }
.yk-frames button:hover { background: var(--yk-muted); }
.yk-frames button[aria-current="true"] { background: var(--yk-accent); width: 1.5rem; }
.yk-index__label { font-family: var(--yk-disp); font-size: .72rem; letter-spacing: .1em; color: var(--yk-muted); text-transform: uppercase; white-space: nowrap; min-width: 4.5rem; }
.yk-progress { position: fixed; left: 0; right: 0; bottom: 0; height: 3px; background: rgba(255,255,255,.06); z-index: 64; }
.yk-progress i { display: block; height: 100%; width: 0; background: var(--yk-accent); box-shadow: 0 0 12px color-mix(in srgb, var(--yk-accent) 60%, transparent); transition: width .12s linear; }

@media (max-width: 760px) {
  .yk-intro h1 { font-size: clamp(2.1rem,10vw,3rem); }
  .yk-track { display: block; height: auto; overflow: visible; scroll-snap-type: none; scroll-behavior: auto; }
  .yk-panel { height: auto; width: 100%; scroll-snap-align: none; border-right: none; border-bottom: 1px solid var(--yk-line); overflow: visible;
    padding: clamp(4.8rem,15vw,6rem) clamp(1.3rem,6vw,2rem) clamp(2.8rem,9vw,3.8rem); justify-content: flex-start; }
  .yk-panel:first-child { min-height: 84vh; min-height: 84svh; justify-content: center; }
  .yk-chapter { font-size: clamp(3rem,16vw,4.5rem); top: auto; bottom: auto; position: relative; left: 0; margin-bottom: .6rem; opacity: .4; }
  .yk-chapter--solid { opacity: .16; }
  .yk-spine { display: none; }
  .yk-intro, .yk-text, .yk-quote, .yk-end { width: 100%; }
  .yk-panel--gallery { width: 100%; padding-right: clamp(1.3rem,6vw,2rem); }
  .yk-rail { display: block; height: auto; padding-right: 0; }
  .yk-rail__head { width: 100%; padding-right: 0; margin-bottom: 1.6rem; }
  .yk-work, .yk-work--wide { width: 100%; margin-bottom: 1.1rem; }
  .yk-work .yk-ph, .yk-work--wide .yk-ph { aspect-ratio: 4/3; }
  .yk-rail__more { width: 100%; padding-left: 0; margin-top: .4rem; }
  .yk-features { flex-direction: column; gap: 1.4rem; }
  .yk-feat { max-width: none; }
  .yk-voices { flex-direction: column; }
  .yk-voice { max-width: none; }
  .yk-index, .yk-progress { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  .yk-track { scroll-behavior: auto; }
  .yk-scrollcue .yk-arrow { animation: none; }
}