Here is the css code for background color:
.instagram{ width:100px; height:100px;
background: #f09433;
background: -moz-linear-gradient(45deg, #f09433 0%, #e6683c 25%, #dc2743 50%, #cc2366 75%, #bc1888 100%);
background: -webkit-linear-gradient(45deg, #f09433 0%,#e6683c 25%,#dc2743 50%,#cc2366 75%,#bc1888 100%);
background: linear-gradient(45deg, #f09433 0%,#e6683c 25%,#dc2743 50%,#cc2366 75%,#bc1888 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr="#f09433", endColorstr="#bc1888",GradientType=1 );
}<div class="instagram"></div>