Get rid of sepia tint on mugshots (jupyter#159)

Author: takluyver

css/logo-nav.css

@@ -441,12 +441,6 @@ body {
     border-radius: 9px;
     /* border: 2px solid lightgray; */
     box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
-    filter: sepia(50%);
-    transition : filter 250ms linear
-}
-
-.material > img:hover {
-    filter: sepia(0%);
 }