[tools][system-analyzer] Landing page layout fix

This CL fixes landing page layout to lists.

Change-Id: I7ce12e20336900b6add45ca7069f0647e282b627
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2302055Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Zeynep Cankara <zcankara@google.com>
Cr-Commit-Position: refs/heads/master@{#68936}

tools/index.html

@@ -54,10 +54,10 @@ a:hover, a:active {
   box-shadow: 0 8px 16px 0 rgba(0,0,0,0.2);
 }
 dd {
-  padding-top: 15px;
+  padding: 10px 10px 10px 10px;
 }
 dt {
-  padding-top: 10px;
+  padding: 10px 10px 10px 10px;
 }
 </style>
 </head>
@@ -65,7 +65,7 @@ dt {
     <div class="content">
       <h1>Welcome to the V8 Tools Landing Page</h1>
       <p>Search through this page to find about the V8 tools to debug, trace and analyze the log files.</p>
-        <div class="grid-container">
+        <dl class="grid-container">
           <div class="card">
             <dt><a href="./callstats.html">Callstats</a></dt>
             <dd>Visualize and compare runtime call stats.</dd>
@@ -110,7 +110,7 @@ dt {
             <dt><a href="https://v8.dev">V8.Dev</a></dt>
             <dd>Check out the V8 website for more information.</dd>
           </div>
-        </div>
+        </dl>
       </div>
     </div>
   </body>