JSFiddle - React, Tailwind, and code Playground

HTML

<body>
        <div id="top">
            <div id="selectReiter" style="display:inline" class="buttonBar">
            <button id="firstButton" class="flatBtn2">  </button> 
                <button id="secondButton" class="flatBtn2">  </button>
                <button id="thirdButton" class="flatBtn2" >  </button>
            </div>
        </div>
    </body>

CSS

#top {
                position: fixed;
                background-color: #AAA;
                background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#fff), to(transparent));
                background-image: -webkit-linear-gradient(top, #fff, transparent);
                background-image: -moz-linear-gradient(top, #fff, transparent);
                background-image: -o-linear-gradient(top, #fff, transparent);
                background-image: linear-gradient(to bottom, #fff, transparent);            
                left: 0px;
                top: 0px;
                width: 100%;
                height: 60px;
                padding: 0px; 
                border: thin solid rgba(0,0,0,0.6);
                color: #444444;
                font-family: Droid sans, Arial, Helvetica, sans-serif;
                font-size: 12px;
                cursor: pointer;
                -webkit-box-shadow: rgba(0,0,0,0.5) 3px 3px 10px;
                -moz-box-shadow: rgba(0,0,0,0.5) 3px 3px 10px;
                box-shadow: rgba(0,0,0,0.5) 3px 3px 10px;
            }

            .flatBtn2 {
                height: 50px;
                width: 50px;
                margin-left: 5px;
                margin-top: 5px;
                float: left;
                display: inline;
            }          

            .flatBtn2:hover {
                background-color: #eee;
                height: 50px;
                width: 50px;
                margin-left: 5px;
                margin-top: 5px;            
                float: left;
                display: inline;
            }       

            .buttonBar {
                float:left;
            }  
            button {
              background-image: url("http://www.chip.de/ii/7/4/3/0/5/7/7/69799fb2e3e4850e.jpg");
            }
            
            button:active, button:focus {
              background-image: none;
            }