theme: use a smaller border-radius for top bar

- plays better with window decorations and maximized windows
- https://bugzilla.gnome.org/show_bug.cgi?id=672430

data/theme/gnome-shell.css

@@ -357,7 +357,7 @@ StScrollBar StButton#vhandle:hover
 }
 
 .panel-corner {
-    -panel-corner-radius: 10px;
+    -panel-corner-radius: 6px;
     -panel-corner-background-color: black;
     -panel-corner-border-width: 2px;
     -panel-corner-border-color: transparent;
@@ -409,7 +409,7 @@ StScrollBar StButton#vhandle:hover
 .panel-button:active,
 .panel-button:overview,
 .panel-button:focus {
-    border-image: url("panel-button-border.svg") 10 10 0 2;
+    border-image: url("panel-button-border.svg") 6 10 0 2;
     background-image: url("panel-button-highlight-wide.svg");
     color: white;
     text-shadow: black 0px 2px 2px;

data/theme/panel-button-border.svg

@@ -9,7 +9,7 @@
    xmlns="http://www.w3.org/2000/svg"
    xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
    xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
-   width="21"
+   width="17"
    height="10"
    id="svg2"
    version="1.1"
@@ -66,9 +66,9 @@
     <rect
        style="opacity:0.8;fill:#ffffff;fill-opacity:1;stroke-width:0.43599999;stroke-miterlimit:4;stroke-dasharray:none"
        id="rect3796"
-       width="3"
+       width="7"
        height="2"
-       x="9"
+       x="5"
        y="8" />
   </g>
 </svg>