DevTools: follow up to r196782 with minor UI fixed.

Source/devtools/front_end/sidebarPane.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 13 matching lines @@
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 .sidebar-pane {
     position: relative;
     flex-direction: column;
     display: flex;
+    flex: none;
 }
 
 .sidebar-pane .info {
     text-align: center;
     font-style: italic;
     padding: 6px;
     color: #888;
 }
 
 .sidebar-pane .section .properties-tree {
@@ skipping 53 matching lines @@
 }
 
 .sidebar-pane > .toolbar {
     border-bottom: 1px solid #ddd;
 }
 
 .sidebar-pane > .toolbar > * {
     pointer-events: auto;
 }
 
-.sidebar-pane-title .sidebar-pane > .toolbar {
+.sidebar-pane-title > .toolbar {
     position: absolute;
     right: 0;
     top: -3px;
 }
 
 .section > .header input[type=checkbox] {
     height: 1em;
     width: 1em;
     margin-left: 0;
     margin-top: 0;
     margin-bottom: 0.25em;
     vertical-align: bottom;
 }
 
 .hidden-callframes-message {
     text-align: center;
     font-style: italic;
     padding: 4px;
     color: #888;
     background-color: #FFFFC2;
 }
 
 .sidebar-pane-button-new-rule {
     background-image: url(Images/paneAddButtons.png);
     background-position: 0 0;
     position: absolute;
     height: 16px;
     width: 23px;
-    right: 2px;
+    right: 5px;
     bottom: 3px;
     visibility: hidden;
 }
 
 .styles-section.matched-styles:not(.read-only):hover .sidebar-pane-button-new-rule {
     visibility: visible;
 }
 
 .sidebar-pane-button-new-rule:hover {
     background-position: -23px 0;
 }