Stronger shadows for widget boxes

- wider shadow on hover
- border radius 3px
Apply border radius to grid--area

app/assets/stylesheets/content/_grid.sass

@@ -20,6 +20,7 @@ body.widget-grid-layout
   position: relative
   overflow: hidden
   min-height: 30px
+  border-radius: 3px
 
   &.-drop-target
     background-color: $gray-light
@@ -29,6 +30,9 @@ body.widget-grid-layout
     @include widget-box--style
     margin: 0
 
+    &:hover
+      @include widget-box--hover-style
+
     .widget-box
       min-height: 200px
       padding: $grid--widget-padding
@@ -127,6 +131,8 @@ body.widget-grid-layout
     background: white
     padding: $grid--widget-padding
     @include widget-box--style
+    @include widget-box--hover-style
+    border-radius: 3px
     margin: 0
 
 .grid--widget-content

app/assets/stylesheets/openproject/_mixins.sass

@@ -62,8 +62,10 @@
 @mixin widget-box--style
   background: $widget-box-block-bg-color
   margin: 10px
-  box-shadow: 0px 0px 9px 0px rgba(0,0,0,0.04)
+  box-shadow: 0px 1px 5px 0px rgba(0,0,0,0.1)
 
+@mixin widget-box--hover-style
+  box-shadow: 0px 1px 20px 0px rgba(0,0,0,0.1)
 
 // These mixins are necessary so that other classes can inherit     the styles.
 // In future Sass versions a doubled inheritance like @extend classA.classB will not work any more.