Snippet for old style callouts in Obsidian 1.0+

obsidian-old-callouts.css

body {
  --callout-border-width:  0 0 0 4px;
  --callout-border-opacity:  1;
  --callout-radius: 0;
  --callout-padding: 0;
  --callout-title-padding:  var(--size-4-4) var(--size-4-4);
  --callout-content-padding:  var(--size-4-2) var(--size-4-4);
}
.callout-title-inner {
  color: var(--text-normal);
}
.callout-content {
  background-color: var(--background-primary-alt);
}