Refactor global.sass file: remove unused styles and fallback image

Author: tacxou

src/assets/sass/global.sass

@@ -30,11 +30,3 @@ body.body--dark
 .sesame-table-td-highlight
   color: $primary
   font-weight: bold
-
-.fallback-image
-  background-image: url('/no-photo.jpg')
-  display: inline-block
-  min-height: 400px
-  background-position: center center
-  background-size: cover
-  background-repeat: no-repeat