:root {
  --bg: #fff8f3;
  --ink: #241713;
  --muted: #76645e;
  --panel: rgba(255, 255, 255, .82);
  --line: rgba(91, 58, 47, .13);
  --brand: #ff7a90;
  --brand-2: #ffb45f;
  --mint: #74d6b2;
  --lavender: #9d8cff;
  --shadow: 0 24px 70px rgba(112, 66, 52, .16);
  --radius: 24px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  font-family: Inter, "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.75;
  background:
    radial-gradient(circle at 14% 9%, rgba(255, 122, 144, .26), transparent 28%),
    radial-gradient(circle at 82% 7%, rgba(116, 214, 178, .24), transparent 28%),
    linear-gradient(135deg, #fff8f3, #f8fbff 55%, #fff2f5);
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
button, input, textarea { font: inherit; }

.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 20;
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px clamp(18px, 4vw, 52px);
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, .78);
  backdrop-filter: blur(18px);
}

.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 900; font-size: 20px; white-space: nowrap; }
.brand span { width: 40px; height: 40px; display: grid; place-items: center; border-radius: 14px; color: white; background: linear-gradient(135deg, var(--brand), var(--brand-2)); box-shadow: 0 14px 26px rgba(255, 122, 144, .28); }
.nav { display: flex; align-items: center; justify-content: center; gap: 6px; flex-wrap: wrap; }
.nav a { padding: 8px 10px; border-radius: 999px; color: var(--muted); font-size: 14px; font-weight: 800; transition: .2s; }
.nav a:hover, .nav a.active { color: var(--ink); background: rgba(255, 122, 144, .12); }
.menu-btn { display: none; width: 44px; height: 44px; border: 1px solid var(--line); border-radius: 999px; background: var(--panel); cursor: pointer; }
.menu-btn span { display: block; height: 2px; width: 18px; margin: 5px auto; border-radius: 2px; background: var(--ink); }

.hero, .section { width: min(1160px, calc(100% - 32px)); margin: 0 auto; }
.hero {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1.04fr .96fr;
  align-items: center;
  gap: 54px;
  padding: 128px 0 72px;
}
.eyebrow { display: inline-flex; padding: 8px 12px; border: 1px solid rgba(255, 122, 144, .26); border-radius: 999px; color: #c64f66; background: rgba(255, 255, 255, .72); font-weight: 900; }
h1 { margin: 18px 0; font-size: clamp(46px, 7.4vw, 88px); line-height: 1.02; letter-spacing: 0; }
h2 { margin: 0; font-size: clamp(31px, 5vw, 56px); line-height: 1.12; letter-spacing: 0; }
h3 { margin: 0 0 10px; line-height: 1.35; }
p { color: var(--muted); }
.lead { max-width: 760px; font-size: clamp(17px, 2vw, 22px); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px; }
.btn, .copy-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 12px 18px;
  background: rgba(255, 255, 255, .82);
  color: var(--ink);
  font-weight: 900;
  cursor: pointer;
  transition: transform .2s, box-shadow .2s, border-color .2s;
}
.btn:hover, .copy-btn:hover { transform: translateY(-2px); border-color: rgba(255, 122, 144, .46); box-shadow: 0 16px 34px rgba(255, 122, 144, .18); }
.primary { border: 0; color: white; background: linear-gradient(135deg, var(--brand), var(--brand-2)); }

.phone-stage { display: grid; place-items: center; }
.phone {
  width: min(360px, 100%);
  min-height: 680px;
  border: 12px solid #2b2424;
  border-radius: 48px;
  padding: 22px;
  background: linear-gradient(180deg, #fff, #fff5f1);
  box-shadow: var(--shadow);
}
.phone-bar { width: 96px; height: 8px; margin: 0 auto 18px; border-radius: 999px; background: #2b2424; opacity: .9; }
.app-card, .diary-preview {
  border: 1px solid var(--line);
  border-radius: 22px;
  padding: 18px;
  background: rgba(255, 255, 255, .82);
}
.app-card span { color: var(--brand); font-weight: 900; }
.app-card strong { display: block; font-size: 32px; }
.photo-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin: 14px 0; }
.photo-grid span { height: 92px; border-radius: 18px; background: linear-gradient(135deg, rgba(255, 122, 144, .45), rgba(116, 214, 178, .42)); }
.mood-row { display: flex; gap: 8px; margin: 14px 0; }
.mood-row b { flex: 1; min-height: 42px; display: grid; place-items: center; border-radius: 999px; background: #fff; border: 1px solid var(--line); }
.phone button { width: 100%; border: 0; border-radius: 18px; padding: 14px; color: white; background: linear-gradient(135deg, var(--brand), var(--lavender)); font-weight: 900; }
.diary-preview { margin-top: 14px; color: var(--muted); }

.section { padding: 92px 0; scroll-margin-top: 86px; }
.soft-band { width: 100%; max-width: none; padding-left: max(16px, calc((100% - 1160px) / 2)); padding-right: max(16px, calc((100% - 1160px) / 2)); background: rgba(255, 255, 255, .48); border-block: 1px solid var(--line); }
.section-title { max-width: 860px; margin-bottom: 28px; }
.section-title span { display: block; color: var(--brand); font-size: 12px; font-weight: 900; letter-spacing: .12em; text-transform: uppercase; margin-bottom: 8px; }
.section-title p { margin: 12px 0 0; }

.cards, .feature-grid, .architecture-grid { display: grid; gap: 16px; }
.three, .architecture-grid { grid-template-columns: repeat(3, 1fr); }
.feature-grid { grid-template-columns: repeat(3, 1fr); }
.card, .feature, .check-panel, .step, .code-card, .prompt-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(16px);
}
.card, .feature, .check-panel, .step { padding: 24px; }
.feature b { color: var(--brand); font-size: 30px; }

.mvp-layout { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.check-list, .x-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; }
.check-list li, .x-list li { position: relative; padding-left: 30px; color: var(--muted); }
.check-list li::before, .x-list li::before {
  position: absolute;
  left: 0;
  top: 1px;
  width: 22px;
  height: 22px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  font-size: 13px;
  font-weight: 900;
}
.check-list li::before { content: "✓"; color: white; background: var(--mint); }
.x-list li::before { content: "−"; color: white; background: var(--brand); }
.muted { background: rgba(255, 255, 255, .6); }

.code-card { margin-top: 22px; overflow: hidden; }
.code-head { display: flex; align-items: center; gap: 8px; padding: 14px 16px; border-bottom: 1px solid var(--line); background: rgba(36, 23, 19, .04); }
.code-head span { width: 12px; height: 12px; border-radius: 50%; background: var(--brand); }
.code-head span:nth-child(2) { background: var(--brand-2); }
.code-head span:nth-child(3) { background: var(--mint); }
pre { margin: 0; padding: 20px; overflow: auto; color: #46322b; }
code { font-family: "Cascadia Code", "SFMono-Regular", Consolas, monospace; }

.timeline { position: relative; display: grid; grid-template-columns: repeat(7, minmax(220px, 1fr)); gap: 16px; overflow-x: auto; padding-bottom: 12px; }
.step span { color: var(--brand); font-weight: 900; }

.prompt-card { position: relative; overflow: hidden; }
.prompt-card pre { max-height: 520px; }
.copy-btn { position: absolute; right: 18px; top: 18px; z-index: 2; }

.to-top {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 12;
  width: 48px;
  height: 48px;
  border: 0;
  border-radius: 50%;
  color: white;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  box-shadow: var(--shadow);
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: .2s;
}
.to-top.show { opacity: 1; pointer-events: auto; }
footer { text-align: center; padding: 32px; color: var(--muted); border-top: 1px solid var(--line); }
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .7s ease, transform .7s ease; }
.reveal.show { opacity: 1; transform: none; }

@media (max-width: 980px) {
  .nav { position: fixed; top: 72px; right: 16px; width: min(340px, calc(100% - 32px)); display: none; flex-direction: column; align-items: stretch; padding: 16px; border: 1px solid var(--line); border-radius: 22px; background: white; box-shadow: var(--shadow); }
  .nav.open { display: flex; }
  .menu-btn { display: block; }
  .hero, .three, .feature-grid, .mvp-layout, .architecture-grid { grid-template-columns: 1fr; }
  .hero { min-height: auto; }
}

@media (max-width: 560px) {
  .hero, .section { width: min(100% - 24px, 1160px); }
  h1 { font-size: 42px; }
  .phone { min-height: 620px; }
}