/* ========================================================================
   森下賢志郎 — site styles
   ======================================================================== */

:root {
  --paper:        #f6f1e6;
  --paper-soft:   #faf6ec;
  --paper-deep:   #ece4d2;
  --rule:         rgba(26,24,21,.18);
  --rule-soft:    rgba(26,24,21,.10);
  --sumi:         #1a1815;
  --sumi-soft:    #2b2723;
  --sumi-mute:    #5e574e;
  --sumi-faint:   #746c62;
  --ai:           #2f4151;

  --serif:        "Hiragino Mincho ProN", "Yu Mincho", "YuMincho",
                  "Noto Serif JP", "Times New Roman", serif;
  --num:          "Hiragino Mincho ProN", "Yu Mincho", "YuMincho", serif;

  --gutter:       max(24px, 4vw);
  --ink-density:  1;
  --rhythm:       1;
}

*,*::before,*::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--serif);
  font-weight: 400;
  font-feature-settings: "palt" 1;
  color: color-mix(in oklab, var(--sumi) calc(100% * var(--ink-density)), var(--paper) 0%);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  line-height: 1.9;
  letter-spacing: .04em;
}
img { max-width: 100%; display: block; }
a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid currentColor;
  padding-bottom: 1px;
  transition: opacity .25s ease;
}
a:hover { opacity: .55; }
button { font: inherit; }
h1, h2, h3, h4 { font-weight: 500; letter-spacing: .06em; margin: 0; }

.rule { height: 1px; background: var(--rule); width: 100%; }
.rule-soft { height: 1px; background: var(--rule-soft); width: 100%; }

/* ── header / nav ──────────────────────────────────────────────────────── */
.site-header {
  position: fixed; inset: 0 0 auto 0;
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px var(--gutter);
  z-index: 50;
  background: linear-gradient(to bottom, var(--paper) 70%, color-mix(in oklab, var(--paper) 80%, transparent));
}
.site-header.is-scrolled {
  border-bottom: 1px solid var(--rule-soft);
  background: color-mix(in oklab, var(--paper) 92%, transparent);
  backdrop-filter: blur(8px);
}
.brand {
  font-size: 17px;
  letter-spacing: .35em;
  text-indent: .35em;
  border: none;
  padding: 0;
  font-weight: 500;
}
.brand .ja { display: inline-block; }
.brand .ja::before {
  content: "";
  display: inline-block;
  width: 22px; height: 1px;
  background: var(--sumi);
  vertical-align: middle;
  margin: 0 14px 4px 0;
}
.nav { display: flex; gap: clamp(20px, 3.5vw, 44px); align-items: center; }
.nav a {
  font-size: 14px;
  letter-spacing: .3em;
  border: none;
  padding-bottom: 2px;
  position: relative;
}
.nav a::after {
  content: "";
  position: absolute; left: 0; right: 100%;
  bottom: -2px;
  height: 1px; background: currentColor;
  transition: right .35s cubic-bezier(.2,.7,.2,1);
}
.nav a:hover::after,
.nav a.is-current::after { right: 0; }
@media (max-width: 720px) {
  .site-header {
    display: grid;
    grid-template-columns: 1fr;
    align-items: start;
    gap: 12px;
    padding-block: 16px 14px;
  }
  .nav {
    display: flex;
    flex-wrap: wrap;
    width: auto;
    max-width: 100%;
    gap: 28px;
  }
  .nav a {
    flex: 0 0 auto;
    font-size: 11px;
    letter-spacing: .12em;
    text-align: left;
    white-space: nowrap;
  }
  .brand { font-size: 14px; letter-spacing: .25em; }
  .brand .ja::before { width: 14px; margin-right: 8px; }
}

/* ── shared layout ─────────────────────────────────────────────────────── */
main { display: block; }
section { padding: calc(120px * var(--rhythm)) var(--gutter); position: relative; }
section.tight { padding-block: calc(80px * var(--rhythm)); }
.section-label {
  display: flex; align-items: center; gap: 14px;
  font-size: 13px; letter-spacing: .35em;
  color: var(--sumi-mute);
  margin-bottom: 36px;
}
.section-label::before {
  content: ""; width: 36px; height: 1px; background: var(--sumi-mute);
}
.section-num {
  font-size: 13px;
  letter-spacing: .3em;
  color: var(--sumi-faint);
}
.eyebrow {
  font-size: 13px;
  letter-spacing: .35em;
  color: var(--sumi-mute);
}

/* ── footer ────────────────────────────────────────────────────────────── */
.site-footer {
  padding: 80px var(--gutter) 50px;
  border-top: 1px solid var(--rule-soft);
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 32px;
  align-items: end;
  font-size: 13px;
  color: var(--sumi-mute);
  letter-spacing: .15em;
}
.site-footer .copy { letter-spacing: .25em; font-size: 12px; }
.site-footer .links { display: flex; gap: 28px; }
.site-footer .links a {
  border: none;
  letter-spacing: .3em;
  font-size: 13px;
}
@media (max-width: 720px) {
  .site-footer { grid-template-columns: 1fr; }
}

/* ── fade in on scroll ────────────────────────────────────────────────── */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 1.1s cubic-bezier(.2,.7,.2,1),
              transform 1.1s cubic-bezier(.2,.7,.2,1);
}
.reveal.is-in { opacity: 1; transform: none; }
.reveal[data-delay="1"] { transition-delay: .12s; }
.reveal[data-delay="2"] { transition-delay: .24s; }
.reveal[data-delay="3"] { transition-delay: .36s; }
.reveal[data-delay="4"] { transition-delay: .48s; }
.reveal[data-delay="5"] { transition-delay: .60s; }

/* ── prose ─────────────────────────────────────────────────────────────── */
.prose p {
  font-size: 15px;
  line-height: 2.1;
  margin: 0 0 1.4em 0;
  max-width: 32em;
  text-wrap: pretty;
}
.prose p.lead {
  font-size: 18px;
  line-height: 2.0;
  letter-spacing: .05em;
}

.kana-num {
  font-size: 12px;
  letter-spacing: .1em;
}

.tate {
  writing-mode: vertical-rl;
  -webkit-writing-mode: vertical-rl;
  text-orientation: upright;
  font-feature-settings: "vert" 1, "vrt2" 1;
}
.tate.mixed { text-orientation: mixed; }