Minor UI improvements

assets/sass/style.sass

@@ -104,6 +104,15 @@ form.upload
       display: none
 
   label
+    position: relative
+    display: inline-block
+    overflow: hidden
+    &:hover,&:focus
+      background: #FFD54F
+      box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2)
+
+    span.text
+      position: relative
       display: inline-block
       background: #FFC107
       padding: 4px 16px
@@ -112,9 +121,15 @@ form.upload
       line-height: 24px
       color: #282828
       cursor: pointer
-    &:hover,&:focus
-      background: #FFD54F
-      box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2)
+      z-index: 1
+
+    input[type=file]
+      position: absolute
+      left: 0
+      right: 0
+      top: 0
+      bottom: 0
+      opacity: 0
 
   input[type=submit]
     display: none