[wwwdocs] Revamp formatting markup of bugs/management.html

Index: gcc.css
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc.css,v
retrieving revision 1.58
diff -u -r1.58 gcc.css
--- gcc.css	2 Sep 2018 13:20:18 -0000	1.58
+++ gcc.css	2 Sep 2018 17:23:57 -0000
@@ -17,6 +17,8 @@ 
 
 .left     { text-align:left; }
 .right    { text-align:right; }
+.center   { text-align:center; }
+.top      { vertical-align:top; }
 
 .no-margin-top { margin-top:0; }
 .twocolumns { column-counts:2; -moz-column-count:2; }

Index: bugs/management.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/bugs/management.html,v
retrieving revision 1.38
diff -u -r1.38 management.html
--- bugs/management.html	1 Sep 2018 23:42:01 -0000	1.38
+++ bugs/management.html	2 Sep 2018 17:28:56 -0000
@@ -86,57 +86,65 @@ 
 <p>The following two fields describe how serious a bug is from a user's
 perspective (Severity) and what Priority we assign to it in fixing it:</p>
 
-<table border="1" cellpadding="4"><tr>
-<td valign="top">
+<table class="padding5" border="1"><tr>
+<td class="top">
 
-<h3 align="center" id="severity">Severity</h3>
+<h3 class="center" id="severity">Severity</h3>
 This field describes the impact of a bug.
+
 <table>
-<tr><th>Critical</th><td>crashes, memory leaks and similar problems on code
-that is written in a common enough style to affect a significant fraction of
-users</td></tr>
-<tr><th>Normal</th><td>major loss of functionality </td></tr>
-<tr><th>Minor</th><td>minor loss of functionality, misspelled word, or other
-problem where an easy workaround exists </td></tr>
-<tr><th>Enhancement</th><td>Request for enhancement</td></tr>
+<tr><th class="right">Critical</th>
+<td>crashes, memory leaks and similar problems on code that is written
+in a common enough style to affect a significant fraction of users</td>
+</tr>
+<tr><th class="right">Normal</th>
+<td>major loss of functionality </td>
+</tr>
+<tr><th class="right">Minor</th>
+<td>minor loss of functionality, misspelled word, or other
+problem where an easy workaround exists </td>
+</tr>
+<tr><th class="right">Enhancement</th>
+<td>Request for enhancement</td>
+</tr>
 </table> 
 
-</td><td valign="top">
+</td><td class="top">
 
-<h3 align="center" id="priority">Priority</h3>
+<h3 class="center" id="priority">Priority</h3>
 For <a href="#regression">regressions</a> this field describes the importance
 and order in which a bug should be fixed.  Priorities are set by
 the release management team only.  If you think a priority is wrong,
 set it to P3 and add a note.
 The available priorities are:
 
-<table cellspacing="3">
+<table>
 <tr>
-  <th valign="top">P1</th>
+  <th>P1</th>
   <td>Most important.  This generally labels a regression which the
     release manager feels should be addressed for the next release
     including wrong-code regressions.<br />
     A P1 regression blocks the release.
   </td>
 </tr><tr>
-  <th valign="top">P2</th>
+  <th>P2</th>
   <td>This generally indicates a regression users will notice on a
     major platform, which is not severe enough to block a release though.
     This includes bugs that were already present in a previous release.
   </td>
 </tr><tr>
-  <th valign="top">P3</th>
+  <th>P3</th>
   <td>The default priority for new PRs which have not been prioritized
     yet.  Priorities below P3 are not on the radar of release management.</td>
 </tr><tr>
-  <th valign="top">P4</th>
+  <th>P4</th>
   <td>An important regression on a platform that is not in the list of
       primary or secondary targets or a regression that users
       will not see for release builds.
       This includes bugs with error-recovery or ice-checking keywords.
   </td>
 </tr><tr>
-  <th valign="top">P5</th>
+  <th>P5</th>
   <td>A less important regression on a platform that is not in the list of
       primary or secondary targets.</td>
 </tr>