rendered paste body#btn{ height: 29px; width: 77px; border: none;}#btn.play {background-image: url("play.gif"); }#btn.pause {background-image: url("pause.gif"); }<button id="btn" class="play"></button> // Does Display<button id="btn" class="pause"></button> // Doesn't display---------------------------------------#btn.pause {background-image: url("pause.gif"); }#btn.play {background-image: url("play.gif"); }<button id="btn" class="play"></button> // Doesn't Display<button id="btn" class="pause"></button> // Does display