Solved Menu bar not showing correct color in Microsoft edge

Hi there
on mccautocentrehull.co.uk the menu bar shows red in chrome - which is correct but shows white in edge - which is not correct - how can i fix this? I am using header style 6 and this is my css in the before section

content: '';
display: block;
position: absolute;
top: 0;
width: 2000px;
left: -318px;
height: 100%;
background: linear-gradient(135deg,rgba(0,0,0,0) 15%,rgb(0,0,0,0) 15%,rgb(0,0,0,0) 15.5%,#FE0000 0%);
z-index: -1;