/* Open3D Viewer — landing page styles.
   Same colour tokens as the native apps so the brand feels consistent
   between web / iOS / Android / Windows. */

:root {
  --bg-deep:   #0a0c10;
  --bg:        #0e1116;
  --bg-elev:   #161a21;
  --bg-elev2:  #1c2129;
  --stroke:    #232934;
  --text-1:    #e7eaef;
  --text-2:    #a5adb8;
  --text-3:    #6d747f;
  --accent:    #ff7a3a;  /* Open3D copper */
  --good:      #4caf6e;
  --max-w:     1180px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg-deep); color: var(--text-1);
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  font-size: 16px; line-height: 1.6; -webkit-font-smoothing: antialiased;
}
a { color: var(--text-1); text-decoration: none; }
a:hover { color: var(--accent); }
img { max-width: 100%; display: block; }

/* ─── Nav ─────────────────────────────────────────────────────── */
.nav {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 24px; background: rgba(14,17,22,0.85); backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--stroke);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 17px; }
.brand img { border-radius: 6px; }
.nav-links { display: flex; align-items: center; gap: 22px; font-size: 14px; }
.nav-links a { color: var(--text-2); }
.nav-links a:hover { color: var(--text-1); }
.nav-links .cta {
  background: var(--accent); color: #0e0907; padding: 8px 14px; border-radius: 10px;
  font-weight: 600; transition: filter .15s;
}
.nav-links .cta:hover { filter: brightness(1.08); color: #0e0907; }

/* ─── Hero ────────────────────────────────────────────────────── */
.hero { max-width: var(--max-w); margin: 0 auto; padding: 56px 24px 28px; text-align: center; }
.hero h1 { font-size: 44px; line-height: 1.15; letter-spacing: -0.02em; margin: 0 0 16px; font-weight: 800; }
.hero h1 .accent { color: var(--accent); }
.hero-sub { color: var(--text-2); font-size: 17px; max-width: 640px; margin: 0 auto 32px; }
.hero-foot { color: var(--text-3); font-size: 13px; margin-top: 18px; }
.hero-foot a { color: var(--text-2); border-bottom: 1px dashed var(--text-3); }

/* Drag-drop zone */
.drop-zone {
  border: 2px dashed var(--stroke); border-radius: 18px;
  background: var(--bg); padding: 40px 24px;
  transition: border-color .15s, background .15s, transform .15s;
  max-width: 640px; margin: 0 auto; cursor: pointer;
}
.drop-zone:hover, .drop-zone.dragover {
  border-color: var(--accent); background: var(--bg-elev);
}
.drop-zone.dragover { transform: scale(1.01); }
.drop-icon { display: block; margin: 0 auto 14px; }
.drop-title { font-size: 18px; font-weight: 600; margin: 0 0 6px; }
.drop-sub { color: var(--text-2); font-size: 14px; margin: 0 0 18px; }
.drop-sub .link {
  background: none; border: 0; color: var(--accent); cursor: pointer;
  text-decoration: underline; font: inherit; padding: 0;
}
.format-pills { display: flex; flex-wrap: wrap; gap: 6px; justify-content: center; }
.format-pills span {
  background: var(--bg-elev2); color: var(--text-2);
  padding: 4px 10px; border-radius: 999px;
  font-size: 11px; font-weight: 600; font-family: ui-monospace, monospace;
  border: 0.5px solid var(--stroke);
}

/* ─── Sections ───────────────────────────────────────────────── */
.section { max-width: var(--max-w); margin: 0 auto; padding: 64px 24px; }
.section-alt { background: var(--bg); max-width: 100%; }
.section-alt > * { max-width: var(--max-w); margin-left: auto; margin-right: auto; }
.section h2 { font-size: 32px; letter-spacing: -0.02em; margin: 0 0 12px; }
.section .lead { color: var(--text-2); font-size: 17px; margin: 0 0 32px; max-width: 720px; }

.format-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 18px;
}
.format-grid article {
  background: var(--bg-elev); border: 0.5px solid var(--stroke);
  border-radius: 14px; padding: 20px;
}
.format-grid h3 {
  margin: 0 0 8px; font-family: ui-monospace, monospace;
  color: var(--accent); font-size: 15px; letter-spacing: 0.08em;
}
.format-grid p { margin: 0; color: var(--text-2); font-size: 14px; }

.feat-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 20px;
}
.feat-grid > div { padding: 4px 0; }
.feat-grid strong { display: block; color: var(--text-1); margin-bottom: 6px; font-size: 16px; }
.feat-grid p { margin: 0; color: var(--text-2); font-size: 14px; }

/* ─── Install cards ─────────────────────────────────────────── */
.install-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; }
.install-card {
  background: var(--bg-elev); border: 0.5px solid var(--stroke); border-radius: 14px;
  padding: 20px; display: flex; flex-direction: column; gap: 4px;
  transition: transform .15s, border-color .15s;
}
.install-card:hover { transform: translateY(-2px); border-color: var(--accent); color: var(--text-1); }
.install-card strong { font-size: 18px; color: var(--text-1); }
.install-card span { color: var(--text-2); font-size: 14px; }
.install-card small { color: var(--accent); font-size: 13px; margin-top: 14px; font-weight: 600; }

/* ─── FAQ ────────────────────────────────────────────────────── */
.faq { margin: 0; }
.faq dt {
  font-weight: 600; font-size: 16px; margin-top: 18px;
  padding-bottom: 6px; border-bottom: 1px solid var(--stroke);
}
.faq dd { margin: 10px 0 0; color: var(--text-2); font-size: 15px; }

/* ─── Ad slots ───────────────────────────────────────────────── */
.ad-slot {
  max-width: var(--max-w); margin: 0 auto; padding: 14px 24px;
  display: flex; justify-content: center; min-height: 100px;
}
.ad-slot ins { width: 100%; max-width: 728px; min-height: 90px; }

/* ─── Footer ─────────────────────────────────────────────────── */
.foot {
  border-top: 1px solid var(--stroke); padding: 28px 24px; margin-top: 40px;
  background: var(--bg);
}
.foot-row {
  max-width: var(--max-w); margin: 0 auto;
  display: flex; gap: 22px; flex-wrap: wrap; align-items: center;
  color: var(--text-3); font-size: 13px;
}
.foot-row a { color: var(--text-3); }
.foot-row a:hover { color: var(--text-1); }

/* ─── Responsive ────────────────────────────────────────────── */
@media (max-width: 760px) {
  .hero h1 { font-size: 32px; }
  .hero-sub { font-size: 15px; }
  .nav-links a:not(.cta) { display: none; }
  .nav-links { gap: 12px; }
  .section { padding: 48px 20px; }
  .section h2 { font-size: 26px; }
  .drop-zone { padding: 28px 16px; }
}