github-base.css

.markdown-alert {
  padding: 0.5rem 1rem;
  margin-bottom: 16px;
  color: inherit;
  border-left: .25em solid #888;
}

.markdown-alert>:first-child {
  margin-top: 0
}

.markdown-alert>:last-child {
  margin-bottom: 0
}

.markdown-alert .markdown-alert-title {
  display: flex;
  font-weight: 500;
  align-items: center;
  line-height: 1
}

.markdown-alert .markdown-alert-title .octicon {
  margin-right: 0.5rem;
  display: inline-block;
  overflow: visible !important;
  vertical-align: text-bottom;
  fill: currentColor;
}

.markdown-alert.markdown-alert-note {
  border-left-color: var(--color-note);
}

.markdown-alert.markdown-alert-note .markdown-alert-title {
  color: var(--color-note);
}

.markdown-alert.markdown-alert-important {
  border-left-color: var(--color-important);
}

.markdown-alert.markdown-alert-important .markdown-alert-title {
  color: var(--color-important);
}

.markdown-alert.markdown-alert-warning {
  border-left-color: var(--color-warning);
}

.markdown-alert.markdown-alert-warning .markdown-alert-title {
  color: var(--color-warning);
}

.markdown-alert.markdown-alert-tip {
  border-left-color: var(--color-tip);
}

.markdown-alert.markdown-alert-tip .markdown-alert-title {
  color: var(--color-tip);
}

.markdown-alert.markdown-alert-caution {
  border-left-color: var(--color-caution);
}

.markdown-alert.markdown-alert-caution .markdown-alert-title {
  color: var(--color-caution);
}