Devtools UI: Behavior and UI update to tooltips

Source/devtools/front_end/ui/tooltip.css

 /*
  * Copyright (c) 2015 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 .tooltip {
-    background: hsl(0, 0%, 20%);
+    background: hsl(0, 0%, 95%);
     border-radius: 2px;
-    color: white;
-    padding: 6px 8px;
+    color: hsl(0, 0%, 20%);
+    padding: 5px 8px;
     font-size: 11px;
     line-height: 14px;
     display: flex;
     align-items: center;
+    -webkit-filter: drop-shadow(0 1px 2px hsla(0, 0%, 0%, 0.3));
+    border: 1px solid hsla(0, 0%, 0%, 0.1);
+    background-clip: padding-box;
+    box-sizing: border-box;
 }
 
-.tooltip,
-.tooltip-arrow {
+.tooltip {
     position: absolute;
     visibility: hidden;
-    transition: visibility 0s 100ms;
+    transition: visibility 0s 100ms, opacity 150ms cubic-bezier(0, 0, .2, 1);
     z-index: 3000;
     top: 0;
     left: 0;
+    opacity: 0;
 }
 
-.tooltip.shown,
-.tooltip.shown + .tooltip-arrow {
+.tooltip.shown {
     visibility: visible;
-    transition-delay: 400ms;
+    transition-delay: 600ms;
+    opacity: 1;
 }
 
-.tooltip.shown.instant,
-.tooltip.shown.instant + .tooltip-arrow {
+.tooltip.shown.instant {
     transition-delay: 0s;
 }
 
-.tooltip-arrow {
-    border: solid;
-    border-color: hsl(0, 0%, 20%) transparent;
-    border-width: 0 4px 4px 4px;
-    margin-left: -4px;
-}
-
-.tooltip-arrow.tooltip-arrow-top {
-    border-width: 4px 4px 0 4px;
-}
-
 .tooltip-shortcut {
-    color: hsl(0, 0%, 80%);
+    color: hsl(0, 0%, 45%);
     display: inline-block;
-    margin-left: 10px;
+    margin-left: 8px;
     flex: 0 0 auto;
 }