/* level1.css — 素のHTML: 最低限の可読性 */

body {
  max-width: 64rem;
  margin: 0 auto;
  padding: 2rem;
  font-family: system-ui, -apple-system, sans-serif;
  line-height: 1.6;
  color: #333;
}

h1 { font-size: 1.75rem; margin: 1rem 0; }
h2 { font-size: 1.375rem; margin: 0.75rem 0; }
h3 { font-size: 1.125rem; margin: 0.5rem 0; }

a { color: #0366d6; }
a:hover { text-decoration: none; }

img { max-width: 100%; height: auto; }

table { border-collapse: collapse; width: 100%; }
th, td { padding: 0.5rem; border-bottom: 1px solid #ddd; text-align: left; }

button, [type="submit"] {
  padding: 0.5rem 1rem;
  cursor: pointer;
  margin: 0.25rem 0;
}

input, textarea, select {
  padding: 0.25rem 0.5rem;
  border: 1px solid #ccc;
  margin: 0.25rem 0;
}

label { display: block; margin-top: 0.5rem; }

header { border-bottom: 1px solid #eee; padding-bottom: 1rem; margin-bottom: 1.5rem; }
footer { border-top: 1px solid #eee; padding-top: 1rem; margin-top: 2rem; font-size: 0.875rem; color: #666; }
nav a { margin-right: 1rem; }

dl { margin: 0.5rem 0; }
dt { font-weight: 600; margin-top: 0.5rem; }
dd { margin-left: 0; }