app.css

:root {
  --bg: #eef2f6;
  --bg-accent: #d9e4ef;
  --ink: #1a2330;
  --muted: #4a5a6a;
  --panel: #ffffff;
  --line: #b7c4d1;
  --focus: #2f5f8a;
  --brand: #1f3d57;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 10% -10%, var(--bg-accent), transparent 60%),
    linear-gradient(180deg, #f7f9fb 0%, var(--bg) 100%);
  font-family: ui-sans-serif, "Segoe UI", "Helvetica Neue", sans-serif;
}

.page {
  width: min(920px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2.5rem 0 3.5rem;
}

.header .brand {
  margin: 0 0 0.35rem;
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--brand);
}

.header h1 {
  margin: 0 0 0.75rem;
  font-size: 1.35rem;
  font-weight: 600;
}

.lede,
.credit {
  color: var(--muted);
  line-height: 1.5;
}

.summary,
.viewer {
  margin-top: 1.75rem;
  padding: 1.25rem 1.35rem;
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  border: 1px solid var(--line);
}

.summary h2,
.viewer h2,
.viewer h3 {
  margin-top: 0;
}

.summary ul {
  margin: 0.75rem 0 1rem;
  padding-left: 1.2rem;
  line-height: 1.55;
}

.field {
  display: block;
  margin-bottom: 0.4rem;
  font-weight: 600;
}

select {
  width: 100%;
  max-width: 100%;
  padding: 0.55rem 0.65rem;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  font: inherit;
}

select:focus,
.panel:focus {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.panel {
  margin: 0.5rem 0 1.25rem;
  padding: 0.85rem 0.95rem;
  max-height: 28rem;
  overflow: auto;
  white-space: pre-wrap;
  word-break: break-word;
  background: #0f1720;
  color: #e8eef4;
  border: 1px solid #2a3644;
  font-family: ui-monospace, Consolas, "Courier New", monospace;
  font-size: 0.86rem;
  line-height: 1.45;
}

@media (max-width: 640px) {
  .page {
    width: min(100% - 1.25rem, 920px);
    padding-top: 1.5rem;
  }

  .header .brand {
    font-size: 1.45rem;
  }
}