diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -10,7 +10,7 @@
     'core.pkg.css' => 'fb144113',
     'core.pkg.js' => 'd3fecc57',
     'darkconsole.pkg.js' => 'ca8671ce',
-    'differential.pkg.css' => 'cc216438',
+    'differential.pkg.css' => '331c38d9',
     'differential.pkg.js' => '11a5b750',
     'diffusion.pkg.css' => '3783278d',
     'diffusion.pkg.js' => '5b4010f4',
@@ -55,7 +55,7 @@
     'rsrc/css/application/countdown/timer.css' => '86b7b0a0',
     'rsrc/css/application/diff/inline-comment-summary.css' => '14a91639',
     'rsrc/css/application/differential/add-comment.css' => 'c478bcaa',
-    'rsrc/css/application/differential/changeset-view.css' => 'd1951f43',
+    'rsrc/css/application/differential/changeset-view.css' => 'df93fa84',
     'rsrc/css/application/differential/core.css' => '7ac3cabc',
     'rsrc/css/application/differential/results-table.css' => '239924f9',
     'rsrc/css/application/differential/revision-comment.css' => '48186045',
@@ -505,7 +505,7 @@
     'conpherence-notification-css' => '403cf598',
     'conpherence-update-css' => '1099a660',
     'conpherence-widget-pane-css' => '87b12e0c',
-    'differential-changeset-view-css' => 'd1951f43',
+    'differential-changeset-view-css' => 'df93fa84',
     'differential-core-view-css' => '7ac3cabc',
     'differential-inline-comment-editor' => 'f2441746',
     'differential-results-table-css' => '239924f9',
diff --git a/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php b/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
@@ -31,6 +31,15 @@
     }
 
     $html = array();
+    $html[] = phutil_tag('colgroup', array(), array(
+      phutil_tag('col', array('class' => 'num')),
+      phutil_tag('col', array('class' => 'left')),
+      phutil_tag('col', array('class' => 'num')),
+      phutil_tag('col', array('class' => 'copy')),
+      phutil_tag('col', array('class' => 'right')),
+      phutil_tag('col', array('class' => 'cov')),
+    ));
+
     $old_lines = $this->getOldLines();
     $new_lines = $this->getNewLines();
     $gaps = $this->getGaps();
diff --git a/webroot/rsrc/css/application/differential/changeset-view.css b/webroot/rsrc/css/application/differential/changeset-view.css
--- a/webroot/rsrc/css/application/differential/changeset-view.css
+++ b/webroot/rsrc/css/application/differential/changeset-view.css
@@ -16,12 +16,30 @@
 .differential-diff {
   background: #fff;
   width: 100%;
+  min-width: 780px;
   border-top: 1px solid {$lightblueborder};
   border-bottom: 1px solid {$lightblueborder};
+  table-layout: fixed;
+}
+
+.differential-diff col.num {
+  width: 45px;
+}
+
+.differential-diff col.left,
+.differential-diff col.right {
+  width: 49.25%;
+}
+
+.differential-diff col.copy {
+  width: 0.5%;
+}
+
+.differential-diff col.cov {
+  width: 1%;
 }
 
 .differential-diff td {
-  min-width: 320px;
   /*
     Disable ligatures in Firefox. Firefox 3 has fancypants ligature support, but
     it gets applied to monospaced fonts, which sucks because it means that the
@@ -35,6 +53,7 @@
   letter-spacing:     0.0083334px;
   vertical-align:     top;
   white-space:        pre-wrap;
+  word-wrap:          break-word;
   padding:            0 8px 1px;
   line-height:        16px;
 }
@@ -42,9 +61,6 @@
 .differential-diff th {
   text-align:         right;
   padding:            2px 6px 0px 0px;
-  width:              4%;
-  min-width:          45px;
-  max-width:          4%;
   vertical-align:     top;
   background:         {$lightbluebackground};
   color:              {$bluetext};
@@ -59,21 +75,6 @@
   -ms-user-select:      none;
   user-select:          none;
 }
-.differential-diff td.left {
-  width: 45%;
-}
-
-.differential-diff td.right,
-.differential-diff td.right1 {
-  width: 43.5%;
-}
-
-.differential-diff td.right2 {
-  width: 44.5%;
-}
-.differential-diff td.right3 {
-  width: 45%;
-}
 
 .differential-changeset-immutable .differential-diff th {
   cursor: auto;
@@ -126,8 +127,6 @@
 }
 
 .differential-diff td.cov {
-  min-width: 1%;
-  width: 1%;
   padding: 0;
 }
 
@@ -252,6 +251,7 @@
   width:              100%;
   -moz-box-sizing:    border-box;
   -webkit-box-sizing: border-box;
+  box-sizing:         border-box;
   overflow:           hidden;
   white-space:        normal;
 }