Themes for Chrome Developer Tools:

Custom.css

/*
  just highlight .selector-matches~
  screenshot: http://i.imgur.com/Do3BDTQ.png
  ref: http://www.lostsaloon.com/technology/using-a-custom-stylesheet-in-a-web-browser/

  css file located on:
    Mac:    ~/Library/Application Support/Google/Chrome/Default/User StyleSheets/Custom.css
    PC:     C:\Users\[USER NAME]\AppData\Local\Google\Chrome\User Data\Default\User StyleSheets\Custom.css
    Ubuntu  (Chromium): ~/.config/chromium/Default/User StyleSheets/Custom.css
            (Google Chrome): ~/.config/google-chrome/Default/User StyleSheets/Custom.css
 */
#-webkit-web-inspector .selector-matches {
  font-weight: bold;
  background-color: #FFCC99;
}