/* ────────────────────────────────────────────
   B2 · SVG Wave Parallax
   複数 SVG 波レイヤーが異速度でスクロール追従 + 横ドリフト
   Pure CSS + JS、外部依存ゼロ
   ──────────────────────────────────────────── */

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:where(html,body){line-break:strict;word-break:normal;overflow-wrap:break-word}
:where(h1,h2,h3,h4){text-wrap:balance}
:where(p,li){text-wrap:pretty}

:root{
  --bg:#f4f3ee;
  --ink:#0a0a0a;
  --muted:#6a6a6a;
  --line:#d8d6cc;
  --paper:#fff;
  --hi:#ff2d55;
  --alt:#0066ff;
  --font:'DM Sans','Noto Sans JP',sans-serif;
  --mono:'JetBrains Mono',monospace;

  /* ── Component variables ── */
  --wp-height:100vh;
  --wp-bg:#f4f3ee;
  --wp-content-w:1100px;
}

html{scroll-behavior:smooth}
body{
  background:var(--bg);color:var(--ink);
  font-family:var(--font);font-weight:400;line-height:1.65;
  min-height:100vh;
}
a{color:inherit;text-decoration:none}

/* ─── HEADER ─── */
header.site{
  position:sticky;top:0;z-index:50;background:var(--bg);
  padding:1rem clamp(1.2rem,4vw,3rem);
  display:flex;align-items:center;justify-content:space-between;gap:1rem;
  border-bottom:1px solid var(--ink);
}
.back{
  font-family:var(--mono);font-size:.78rem;letter-spacing:.18em;
  display:inline-flex;align-items:center;gap:.6em;
}
.back .arrow{transition:transform .25s}
.back:hover .arrow{transform:translateX(-.3em)}
.cell-marker{
  font-family:var(--mono);font-size:.78rem;letter-spacing:.22em;color:var(--hi);
}

/* ────────────────────────────────────────────
   COMPONENT: .wave-parallax
   ──────────────────────────────────────────── */
.wave-parallax{
  position:relative;
  min-height:var(--wp-height);
  overflow:hidden;
  background:var(--wp-bg);
  isolation:isolate;
}

.wp-content{
  position:relative;z-index:2;
  max-width:var(--wp-content-w);margin:0 auto;
  padding:clamp(4rem,12vh,8rem) clamp(1.5rem,5vw,4rem) clamp(8rem,18vh,12rem);
  display:flex;flex-direction:column;align-items:flex-start;gap:1.2rem;
  min-height:var(--wp-height);
  justify-content:center;
}

.wp-kicker{
  font-family:var(--mono);font-size:.74rem;letter-spacing:.25em;
  padding:.3em .9em;border:1px solid var(--ink);
  background:var(--bg);
}

.wp-title{
  font-weight:700;
  font-size:clamp(2.4rem,7.5vw,5.4rem);
  line-height:1;letter-spacing:-.02em;
}
.wp-title span{display:inline-block}
.wp-title .accent{
  background:linear-gradient(transparent 62%,var(--hi) 62%,var(--hi) 92%,transparent 92%);
  padding:0 .08em;
}

.wp-lead{
  font-size:clamp(1rem,1.3vw,1.1rem);
  color:var(--muted);
  max-width:36em;
}

.wp-scroll-cue{
  margin-top:1rem;
  font-family:var(--mono);font-size:.74rem;letter-spacing:.25em;color:var(--muted);
  display:inline-flex;align-items:center;gap:.7em;
}
.wp-scroll-cue .arr{
  display:inline-block;
  animation:wp-bounce 1.8s cubic-bezier(.5,0,.5,1) infinite;
}
@keyframes wp-bounce{
  0%,100%{transform:translateY(0);opacity:1}
  50%{transform:translateY(.4em);opacity:.4}
}

/* ─── Wave layers ─── */
.wp-layers{
  position:absolute;left:0;right:0;bottom:0;
  pointer-events:none;
  z-index:1;
  height:60%;
  min-height:320px;
}
.wp-layer{
  position:absolute;left:0;right:0;
  /* bottom & height are set by JS (sectionH px buffer below section) */
  bottom:0;
  height:320px;
  transform:translate3d(0,var(--scroll-y,0),0);
  will-change:transform;
}
.wp-layer svg{
  display:block;
  position:absolute;top:0;left:0;
  width:200%;
  height:320px;             /* fixed: matches viewBox height */
  animation:wp-drift var(--drift-dur,30s) linear infinite;
  will-change:transform;
}
/* Buffer block below the SVG. As the layer translates up,
   this solid block emerges from below section bottom and
   keeps the bottom of the viewport filled with wave color. */
.wp-layer::after{
  content:"";
  position:absolute;
  top:320px;left:0;right:0;bottom:0;
  background:var(--wave-color,transparent);
}
@keyframes wp-drift{
  from{transform:translate3d(0,0,0)}
  to{transform:translate3d(-50%,0,0)}
}

/* ────────────────────────────────────────────
   END COMPONENT
   ──────────────────────────────────────────── */


/* ─── Continuation section ─── */
.continuation{
  background:var(--ink);color:#fff;
  padding:clamp(5rem,12vh,9rem) clamp(1.5rem,4vw,3rem);
}
.cont-inner{
  max-width:46em;margin:0 auto;
}
.cont-inner .kicker{
  display:inline-block;
  font-family:var(--mono);font-size:.74rem;letter-spacing:.25em;color:var(--hi);
  padding:.3em .9em;border:1px solid var(--hi);
  margin-bottom:1.5rem;
}
.cont-inner h2{
  font-weight:700;font-size:clamp(1.6rem,3vw,2.4rem);
  line-height:1.2;letter-spacing:-.01em;
  margin-bottom:1.2rem;
}
.cont-inner p{
  font-size:.95rem;line-height:2;color:#ccc;
}
.cont-inner code{
  font-family:var(--mono);font-size:.85em;
  background:#1a1a1a;padding:.12em .45em;color:#fff;border:1px solid #333;
}

/* ─── Notes section ─── */
section.notes{
  max-width:1100px;margin:0 auto;
  padding:clamp(3rem,6vw,5rem) clamp(1.5rem,4vw,3rem);
}
.shou{
  display:flex;align-items:baseline;justify-content:space-between;gap:1rem;flex-wrap:wrap;
  padding-bottom:1rem;border-bottom:1px solid var(--ink);margin-bottom:2.5rem;
}
.shou h2{font-size:clamp(1.3rem,2vw,1.7rem);font-weight:700;letter-spacing:.04em}
.shou .no{font-family:var(--mono);font-size:.78rem;letter-spacing:.25em;color:var(--muted)}

.notes-grid{
  display:grid;grid-template-columns:1fr;gap:1.2rem;
  margin-bottom:3rem;
}
@media(min-width:780px){.notes-grid{grid-template-columns:repeat(3,1fr)}}
.note{
  position:relative;
  background:var(--paper);border:1px solid var(--ink);
  padding:1.5rem 1.4rem 1.4rem;
}
.note-no{
  position:absolute;top:1rem;right:1rem;
  font-family:var(--mono);font-size:.7rem;letter-spacing:.2em;color:var(--muted);
}
.note h3{font-size:1.02rem;font-weight:700;margin-bottom:.7rem;letter-spacing:.02em}
.note p{font-size:.86rem;color:var(--muted);line-height:1.8}
.note code{
  font-family:var(--mono);font-size:.85em;
  background:var(--bg);padding:.1em .35em;border:1px solid var(--line);
}

.sub-h{
  font-size:1rem;font-weight:700;letter-spacing:.04em;
  margin:2rem 0 1rem;padding-bottom:.7rem;
  border-bottom:1px dashed var(--ink);
}

.vars{
  display:grid;grid-template-columns:1fr;gap:0;
  border:1px solid var(--ink);background:var(--paper);
}
.var{
  display:grid;
  grid-template-columns:minmax(11rem,auto) 1fr auto;
  gap:1rem;
  padding:.8rem 1rem;
  border-bottom:1px solid var(--line);
  align-items:center;
}
.var:last-child{border-bottom:none}
.var code{
  font-family:var(--mono);font-size:.82rem;color:var(--hi);
  font-weight:500;
}
.var span{font-size:.85rem;color:var(--muted);line-height:1.5}
.var em{
  font-family:var(--mono);font-size:.78rem;font-style:normal;
  color:var(--ink);background:var(--bg);
  padding:.15em .55em;border:1px solid var(--line);
  white-space:nowrap;
}
@media(max-width:680px){
  .var{grid-template-columns:1fr;gap:.3rem;padding:.9rem 1rem}
  .var em{justify-self:start}
}

/* ─── FOOTER ─── */
footer{
  padding:2rem clamp(1.2rem,4vw,3rem) 1.5rem;
  display:flex;flex-wrap:wrap;gap:1rem;justify-content:space-between;align-items:center;
  font-family:var(--mono);font-size:.72rem;letter-spacing:.2em;color:var(--muted);
  border-top:1px solid var(--ink);
}
footer a{color:var(--ink)}

/* Reduced motion: skip the drift, freeze layers, keep static composition */
@media (prefers-reduced-motion: reduce){
  .wp-layer svg{animation:none}
  .wp-layer{transform:none !important}
  .wp-scroll-cue .arr{animation:none}
}