editor.css in The CodeMirror Editor 8

.CodeMirror {
  height: auto;
  border: solid 1px #bbb;
  font-size: 14px;
}

.cme-readonly .CodeMirror-cursor {
  display: none !important;
}

.cme-error {
  border-color: #e62600;
}

.CodeMirror pre.CodeMirror-placeholder {
  color: #999;
}