*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #f6f4ef;
  --surface: #efede8;
  --text: #1c1a17;
  --muted: #7a7570;
  --accent: #1d6ef5;
  --divider: #e0ddd7;
}

html {
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

/* Viewport border frame */
html::before {
  content: '';
  position: fixed;
  inset: 10px;
  border: 1.5px solid var(--divider);
  border-radius: 16px;
  pointer-events: none;
  z-index: 9999;
  box-shadow: 0 0 0 10px var(--bg);
}

body {
  max-width: 560px;
  margin: 0 auto;
  padding: 72px 28px 64px;
  text-align: center;
}

/* Header */

header {
  margin-bottom: 32px;
}

.icon-wrap {
  margin-bottom: 28px;
}

.icon-wrap img {
  width: 96px;
  height: 96px;
  border-radius: 22px;
  display: block;
  margin: 0 auto;
}

header h1 {
  font-size: 2.6rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: 10px;
}

.tagline {
  font-size: 1.2rem;
  color: var(--muted);
  margin-bottom: 28px;
  font-weight: 400;
}

.cta-row {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}


.download-btn {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  padding: 11px 24px;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  border-radius: 12px;
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  transition: filter 0.15s;
  line-height: 1.3;
}

.download-btn:hover { filter: brightness(1.1); }

.download-version {
  font-size: 0.7rem;
  font-weight: 400;
  opacity: 0.75;
  letter-spacing: 0.02em;
}

.cta-note {
  font-size: 0.85rem;
  color: var(--muted);
  padding-top: 17px;
}

.download-count {
  margin-top: 14px;
  font-size: 0.78rem;
  color: var(--muted);
  text-align: center;
}

/* Sections */

.section {
  padding: 32px 0;
  border-top: 1px solid var(--divider);
}

.section-label {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
  opacity: 0.8;
  text-align: center;
}

.section h2 {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.25;
  margin-bottom: 16px;
  text-align: center;
}

.section h3 {
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: -0.01em;
  line-height: 1.4;
  margin-bottom: 16px;
  text-align: center;
}

.section p:not(.section-label) {
  color: #3d3a35;
  margin-bottom: 32px;
  text-align: left;
  line-height: 2;
  font-size: 1rem;
}

.section p:last-child { margin-bottom: 0; }

/* Premise list */

.premise-points {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 4px;
}

.premise-points li {
  color: #3d3a35;
  padding: 10px 14px;
  background: var(--surface);
  border-radius: 10px;
  font-size: 0.95rem;
  line-height: 1.5;
  text-align: left;
}

/* Feature chips */

.features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 4px;
}

.features li {
  color: #3d3a35;
  padding: 10px 14px;
  background: var(--surface);
  border-radius: 10px;
  font-size: 0.95rem;
  line-height: 1.5;
  text-align: left;
}

/* Requirements */

.req-box {
  background: var(--surface);
  border-radius: 12px;
  padding: 18px 20px;
  font-size: 0.93rem;
  color: #3d3a35;
  line-height: 1.6;
  text-align: left;
}

.req-box strong { color: var(--text); }

/* Footer */

footer {
  padding-top: 48px;
  border-top: 1px solid var(--divider);
  font-size: 0.82rem;
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

footer a {
  color: var(--muted);
  text-decoration: none;
}

footer a:hover { color: var(--text); }

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131210;
    --surface: #1e1c19;
    --text: #f0ece6;
    --muted: #7a7670;
    --accent: #4d8eff;
    --divider: #2c2a27;
  }

  .section p:not(.section-label), .premise-points li, .features li, .req-box { color: #d0cdc7; }
  .req-box strong { color: var(--text); }
}

@media (max-width: 480px) {
  html::before { display: none; }
  body { padding: 48px 20px 48px; }
  header h1 { font-size: 2rem; }
  .cta-row { flex-direction: column; align-items: center; gap: 10px; }
}