common-styles.css

/* 
These are all styles intended for presentational purposes 
and aren't important for the content mentioned in the article
*/
body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, Segoe UI, Roboto,
    Helvetica Neue, Arial, Noto Sans, sans-serif, Apple Color Emoji,
    Segoe UI Emoji, Segoe UI Symbol, Noto Color Emoji;
  margin: 1em;
}

:root {
  --pale-blue: #4299e1;
}

* {
  box-sizing: border-box;
}

[lang="ja"] {
  font-family: "ヒラギノ角ゴ Pro W3", "Hiragino Kaku Gothic Pro", Osaka,
    メイリオ, Meiryo, "ＭＳ Ｐゴシック", "MS PGothic", "ＭＳ ゴシック",
    "MS Gothic", "Noto Sans CJK JP", TakaoPGothic, sans-serif;
}

h1 {
  color: var(--pale-blue);
  font-size: 1.5rem;
}

h2 {
  font-size: 1.2rem;
}

a {
  text-decoration: none;
  color: var(--pale-blue);
}

ul {
  list-style: none;
}

ul li::before {
  content: "\2022";
  color: var(--pale-blue);
  font-weight: bold;
  display: inline-block;
  width: 1em;
  margin-left: -1em;
}

header nav a {
  padding: 0.5rem 0.5rem;
}
header nav a.active {
  border-bottom: 1px solid var(--pale-blue);
}

footer {
  margin-top: 1rem;
}