:root {
  color-scheme: light;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: #1f2937;
  background: #f3f6fa;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  --ink: #1f2937;
  --accent: #176b87;
  --accent-dark: #10546c;
  --line: #d8e1eb;
  --surface: #ffffff;
  --demo-surface: #e6eef4;
}

body {
  box-sizing: border-box;
  min-height: 100vh;
  margin: 0;
  padding: clamp(1.25rem, 4vw, 3.5rem);
  background: #f3f6fa;
  color: var(--ink);
  font-size: 16px;
  line-height: 1.6;
}

h1,
h2 {
  line-height: 1.2;
  letter-spacing: -0.025em;
}

h1 {
  margin: 1.4rem 0 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid #c7dce5;
  color: #162c3b;
  font-size: clamp(1.65rem, 3vw, 2.35rem);
}

h2 {
  margin: 2rem 0 0.75rem;
  color: #29485b;
  font-size: clamp(1.15rem, 2vw, 1.4rem);
}

a {
  color: var(--accent);
  font-weight: 600;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--accent-dark);
}

a:focus-visible {
  border-radius: 4px;
  outline: 3px solid #71bad0;
  outline-offset: 3px;
}

body > a[href="index.html"] {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.8rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  font-size: 0.9rem;
  text-decoration: none;
  box-shadow: 0 2px 5px rgb(28 47 66 / 5%);
}

body > a[href="index.html"]::before {
  content: "←";
  font-size: 1.1em;
}

div.content {
  display: grid;
  gap: 0.85rem;
  margin: 0 0 2.25rem;
}

textarea {
  box-sizing: border-box;
  display: block;
  width: 100%;
  min-width: 0;
  padding: 1rem 1.15rem;
  overflow: auto;
  border: 1px solid #263f53;
  border-radius: 12px;
  background: #172a3a;
  color: #e5eff7;
  font: 0.875rem/1.55 ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  tab-size: 4;
  resize: vertical;
  box-shadow: 0 5px 14px rgb(24 43 61 / 10%);
}

textarea:focus-visible {
  outline: 3px solid #71bad0;
  outline-offset: 2px;
}

section {
  background-color: var(--demo-surface);
  color: var(--ink);
  outline: 1px solid #cfdae4;
  outline-offset: 0;
}

box {
  background-color: #fff;
  color: #203748;
  padding: 1em;
  margin: 1em;
  border-radius: 8px;
  box-shadow: 0 2px 7px rgb(31 52 70 / 9%);
}

section,
textarea {
  border-radius: 12px;
}

body > ol {
  max-width: 54rem;
  margin: 1.5rem 0 0;
  padding: 0;
  list-style: none;
}

body > ol li {
  margin: 0.75rem 0;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  box-shadow: 0 3px 10px rgb(28 47 66 / 5%);
  transition: border-color 140ms ease, box-shadow 140ms ease, transform 140ms ease;
}

body > ol li:hover {
  transform: translateY(-1px);
  border-color: #a9c8d5;
  box-shadow: 0 7px 16px rgb(28 47 66 / 9%);
}

body > ol li a {
  display: block;
  padding: 1rem 1.15rem;
  text-decoration: none;
}

@media (max-width: 600px) {
  body {
    padding: 1.1rem;
    font-size: 15px;
  }

  h1 {
    margin-top: 1.1rem;
  }

  body > ol li a {
    padding: 0.85rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  body > ol li {
    transition: none;
  }
}