Bug 1258109 - Fix the tab start- and end background. r=mkmelin

MozReview-Commit-ID: 34WIXnCSKy

mail/themes/linux/mail/tabs/selected-end.svg

@@ -18,7 +18,7 @@
 
       #tab-background-fill {
         background-color: -moz-dialog;
-        background-image: linear-gradient(transparent 0px, transparent 2px, hsla(0,0%,100%,0.35) 2px, hsla(0,0%,100%,0.35) 3px, hsla(0,0%,100%,0.65) 3px, hsla(0,0%,100%,0.65) 4px, rgba(255,255,255,.3));
+        background-image: linear-gradient(transparent 2px, rgba(255,255,255,.4) 2px, rgba(255,255,255,.4));
         background-repeat: no-repeat;
         height: 100%;
         width: 100%;

mail/themes/linux/mail/tabs/selected-start.svg

@@ -18,7 +18,7 @@
 
       #tab-background-fill {
         background-color: -moz-dialog;
-        background-image: linear-gradient(transparent 0px, transparent 2px, hsla(0,0%,100%,0.35) 2px, hsla(0,0%,100%,0.35) 3px, hsla(0,0%,100%,0.65) 3px, hsla(0,0%,100%,0.65) 4px, rgba(255,255,255,.3));
+        background-image: linear-gradient(transparent 2px, rgba(255,255,255,.4) 2px, rgba(255,255,255,.4));
         background-repeat: no-repeat;
         height: 100%;
         width: 100%;