Um CSS para estilizar artigos --- normalmente convertidos de markdown.

md.css

.md {
  line-height: 180%;
  font-size: 16px;
  font-family: Helvetica, Arial, sans-serif;
}

.md * {
  box-sizing: border-box;
}

.md p {
  margin-top: 0;
  margin-bottom: .25em;
}

.md ul p,
.md ol p {
  margin: 0;
}
.md ul li,
.md ol li {
  margin-bottom: .75em;
}

.md h1,
.md h2,
.md h3,
.md h4,
.md h5,
.md h6 {
  padding-bottom: .25em;
  margin-top: .25em;
  margin-bottom: .75em;
  border-bottom: solid 1px #f5f5f5;
}

.md h1 { font-size: 2.5em; }
.md h2 { font-size: 2em; }
.md h3 { font-size: 1.75em; }
.md h4 { font-size: 1.5em; }
.md h5 { font-size: 1.25em; }
.md h6 { font-size: 1em }

.md pre,
.md code {
  background-color: #eee;
}
.md code {
  padding: .05em .15em;
}
.md pre code {
  padding: unset;
  background-color: unset;
}
.md pre {
  padding: 1em 1.25em;
  overflow-x: auto;
}

.md blockquote {
  margin: 0;
  padding-left: 1em;
  border-left: solid .25em gray;
  color: gray;
}