JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id='top'></div>
    <div id='left'>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br></div>
    <div id='right'>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br><div class="fileform">
<div id="fileformlabel"></div>
<div class="selectbutton">выбрать </div>
<input type="file" name="upload" id="upload" onchange="getName(this.value);" />
</div><br>1<br>1<br>1<br>1<br></div>
    <div id='bottom'></div>
</body>

CSS

html, body {
    height: 100%;
    margin: 0
}

body {   
    position: relative;
}

#top {
    height: 30px;
    background: yellow;
}


#bottom {
    position: fixed;
    bottom:0;
    height: 10px;
    background: blue;
    width: 100%;
}

#left {
    position: fixed;
    width: 100px;
    background: red;
    left:0;
    top: 0;
    bottom: 0;
    overflow-y: auto;
    color: #fff;
    margin: 30px 0 10px;
    z-index: 10;
}

#right {
    position: fixed;
    width: 100%;
    right:0;
    top: 0;    
    bottom: 0;
    margin: 30px 0 10px 110px;
    padding-left: 110px;
    overflow-y: auto;
    background: green;
    color: white;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}
.fileform { 
    cursor: pointer;
    height: 26px;
    overflow: hidden;
    position: relative;
    text-align: left;
    vertical-align: middle;
    width: 80px;
}
 
.fileform .selectbutton { 
    background-color: #A2A3A3;
    border: 1px solid #939494;
    border-radius: 2px;
    color: #FFFFFF;
    float: right;
    font-size: 16px;
    height: 20px;
    line-height: 20px;
    overflow: hidden;
    padding: 2px 6px;
    text-align: center;
    vertical-align: middle;
    width: 60px;
}
 
.fileform #upload{
    position:absolute; 
    top:0; 
    left:0; 
    width:100%; 
    -moz-opacity: 0; 
    filter: alpha(opacity=0); 
    opacity: 0; 
    font-size: 150px; 
    height: 30px; 
    z-index:20;
    cursor: pointer;
}
.fileform #fileformlabel { 
float: left;
height: 22px;
line-height: 22px;
overflow: hidden;
text-align: left;
vertical-align: middle;
}

JavaScript

function getName (str){
    if (str.lastIndexOf('\\')){
        var i = str.lastIndexOf('\\')+1;
    }
    else{
        var i = str.lastIndexOf('/')+1;
    }						
    var filename = str.slice(i);			
    var uploaded = document.getElementById("fileformlabel");
    uploaded.innerHTML = filename;
}