.CodeMirror-foldmarker {
    color: blue;
    cursor: pointer;
    font-family: arial;
    line-height: .3;
    text-shadow: #b9f 1px 1px 2px, #b9f -1px -1px 2px, #b9f 1px -1px 2px, #b9f -1px 1px 2px;
}

.CodeMirror-foldgutter { width: .7em; }

.CodeMirror-foldgutter-open,
.CodeMirror-foldgutter-folded { cursor: pointer; }

.CodeMirror-foldgutter-open:after { content: "\25BE"; }

.CodeMirror-foldgutter-folded:after { content: "\25B8"; }