body{
    background-color:#f9f9f9;
    display:flex;
    flex-direction:row;
    justify-content:center;
    width:100%;
    margin:0;
    padding-top:40px; /*This value should be used as Top in Fixed class */
    padding-bottom:40px;

}

aside{
    background-color:#fff;
    border-radius:10px;
    margin-top:100px; /*This property should be set to 0 in Fixed class */
    width:25%;
    height:400px;
    margin-right:15px;
    -webkit-box-shadow: 0px 0px 9px 0px rgba(0,0,0,0.15);
    -moz-box-shadow: 0px 0px 9px 0px rgba(0,0,0,0.15);
    box-shadow: 0px 0px 9px 0px rgba(0,0,0,0.15);
}

main{
    background-color:#efefef;
    border-radius:10px;
    width:50%;
    height:1500px;
    margin-left:15px;
}

.fixed{
    position:sticky;
    margin-top:0;
    top:40px;
}