作业部落，用来写 Markdown，挺好的，不过样式不太符合我的心意，好在提供自定义功能...

h1 {
  color: Green;
  font-size: 40px;
  font-weight: bold;
}
h2 {
  font-size: 35px;
  width: 834px;
  padding: 8px;
  background-color: LightGreen;
  border-bottom: 1px solid #e2e3e4;
  border-radius: 5px;
}
h3 {
  font-size: 32px;
}
h4 {
  font-size: 28px;
}
h5 {
  font-size: 25px;
}
h6 {
  font-size: 22px;
}
h4,
h5,
h6 {
  margin: 20px 0;
}
kbd {
  display: inline-block;
  margin: 0 0.1em;
  padding: 0.1em 0.6em;
  font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
  font-size: 11px;
  line-height: 1.4;
  color: #242729;
  text-shadow: 0 1px 0 #fff;
  background-color: #e1e3e5;
  border: 1px solid #adb3b9;
  border-radius: 3px;
  box-shadow:
    0 1px 0 rgba(12, 13, 14, 0.2),
    0 0 0 2px #fff inset;
  white-space: nowrap;
}
h1 code,
h2 code,
h3 code,
h4 code,
h5 code,
h6 code {
  font-size: inherit;
}