:root {
  --ink: #1a1a1a;
  --muted: #555;
  --line: #e3e3e3;
  --link: #0b57d0;
  --bg: #fff;
  --maxw: 46rem;
}

* { box-sizing: border-box; }

html {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
  -webkit-text-size-adjust: 100%;
}

body { margin: 0; }

.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 1.25rem;
}

a { color: var(--link); }

/* header / footer */
.site-header {
  padding: 1.4rem 0;
  border-bottom: 1px solid var(--line);
}
.site-header .wrap {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
}
.brand {
  font-weight: 600;
  text-decoration: none;
  color: var(--ink);
}
.site-header nav a {
  margin-left: 1.1rem;
  text-decoration: none;
  color: var(--link);
}
/* current page: same link colour, just bolder — avoids the
   "black vs blue" contrast reading as if the blue one is active */
.site-header nav a[aria-current="page"] { font-weight: 700; }

.site-footer {
  margin-top: 4rem;
  padding: 1.4rem 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: .9rem;
}

/* content */
main.wrap { padding-top: 2.5rem; padding-bottom: 1rem; }

h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  line-height: 1.2;
  margin: 0 0 1rem;
}
h3 {
  font-size: 1.15rem;
  margin: 1.6rem 0 .6rem;
}
.lead { color: var(--muted); margin: 0 0 2rem; }

/* the comparison form (tool emits inline float:left / width:49% wrappers) */
main form { margin-top: 1rem; }
main textarea {
  width: 100%;
  font: .95rem/1.5 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  padding: .6rem;
  border: 1px solid #999;
  border-radius: 4px;
  resize: vertical;
}
main input[type="image"] { margin-top: 1rem; }

/* diff result blocks */
main h3 + div { font-size: .95rem; }

@media (max-width: 34rem) {
  main form div[style*="float"] {
    float: none !important;
    width: 100% !important;
  }
}