I am using bootstrap modal. When modal is open background content opacity is not changed by default. I tried changing in js using
function showModal() {
doc
Just setting height to 100% won't be the solution if you have a background page whose height extends beyond browser height.
Adding to Bhargavi's answer, this is the solution when you have scrollable page in the background.
.modal-backdrop.in
{
opacity:0.5 !important;
position:fixed;// This makes it cover the entire scrollable page, not just browser height
height:100%;
}