追加の要素といくつかの JavaScript を使用してそれを行うことができます。このような:
#some-section {
position: relative;
}
#some-section .after {
background-image: -webkit-linear-gradient(rgba(255, 255, 255, 0), white);
background-image: -moz-linear-gradient(rgba(255, 255, 255, 0), white);
background-image: -ms-linear-gradient(rgba(255, 255, 255, 0), white);
background-image: -o-linear-gradient(rgba(255, 255, 255, 0), white);
background-image: linear-gradient(rgba(255, 255, 255, 0), white);
bottom: 0;
left: 0;
height: 20px; /* Whatever suits you */
position: absolute;
right: 0;
}
そして JavaScript:
var section = document.getElementById('some-section');
var after = document.createElement('div');
after.className = 'after';
section.appendChild(after);
section.addEventListener('scroll', function() {
after.style.bottom = -section.scrollTop + 'px';
}, false);
これが実際のデモです。