apankrat/js-noisy-gradient – js библиотека для сглаживания линейного градиента
var nvg = new NoisyVerticalGradient(50, 400, ['#112233', '#223344'] );
var png = nvg.render_png();
document.getElementById('xyz').style.backgroundImage = png;
var nvg = new NoisyVerticalGradient(50, 400, ['#112233', '#223344'] );
var png = nvg.render_png();
document.getElementById('xyz').style.backgroundImage = png;