.CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}
.cm-trailingspace {
background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAQAAAACCAYAAAB/qH1jAAAABmJLR0QA/wD/AP+gvaeTAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB3RJTUUH3QUXCToH00Y1UgAAACFJREFUCNdjPMDBUc/AwNDAAAFMTAwMDA0OP34wQgX/AQBYgwYEx4f9lQAAAABJRU5ErkJggg==);
background-position: bottom left;
background-repeat: repeat-x;
}