codemirror/addon/search/matchesonscrollbar.css

Full-featured in-browser code editor

.CodeMirror-search-match {
  background: gold;
  border-top: 1px solid orange;
  border-bottom: 1px solid orange;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  opacity: .5;
}