Hide line below search bar in dark themes

The results return an empty div with a background color set (not sure
why, not generated on Whoogle's side). This unsets the background color
so that at least it isn't visible.

app/static/css/dark-theme.css

@@ -70,6 +70,10 @@ select {
     border-radius: 8px !important;
 }
 
+.BsXmcf {
+    background-color: unset !important;
+}
+
 .KP7LCb {
     box-shadow: 0 0 0 0 !important;
 }