To update the footer styling, you should remove the height property and make the following adjustments:
.footer{
background-color: #000;
text-align: center;
color: #FFF;
bottom: 0px;
padding-bottom: 0px;
position: fixed;
right: 0px;
left: 0px;
}
Regarding the gradient placement, it seems there is an error in implementing the gradient. I suggest referring to the linear-gradient documentation for proper guidance. However, you can incorporate the code below:
#grad {
background: -webkit-linear-gradient(left, #3BD99F, #9600FA); /* Safari 5.1 to 6.0 */
background: -o-linear-gradient(left, #3BD99F, #9600FA); /* Opera 11.1 to 12.0 */
background: -moz-linear-gradient(left, #3BD99F, #9600FA); /* Firefox 3.6 to 15 */
background: linear-gradient(left, #3BD99F, #9600FA); /* Standard syntax */
}