diff --git a/course/format/lams/format.php b/course/format/lams/format.php
index c312c9dac86..056003be8f7 100644
--- a/course/format/lams/format.php
+++ b/course/format/lams/format.php
@@ -65,7 +65,7 @@ echo '<table id="layout-table" cellspacing="0"><tr>';
 /// The left column ...
 
 if (blocks_have_content($pageblocks, BLOCK_POS_LEFT) || $editing) {
-    echo '<td width="'.$preferred_width_left.'" id="left-column">';
+    echo '<td style="width:'.$preferred_width_left.'px" id="left-column">';
     blocks_print_group($PAGE, $pageblocks, BLOCK_POS_LEFT);
     echo '</td>';
 }
@@ -331,7 +331,7 @@ echo '</td>';
 
 // The right column
 if (blocks_have_content($pageblocks, BLOCK_POS_RIGHT) || $editing) {
-    echo '<td width="'.$preferred_width_right.'" id="right-column">';
+    echo '<td style="width:'.$preferred_width_right.'px" id="right-column">';
     blocks_print_group($PAGE, $pageblocks, BLOCK_POS_RIGHT);
     echo '</td>';
 }
diff --git a/course/format/scorm/format.php b/course/format/scorm/format.php
index 2ca446d5648..64ae5afe47d 100644
--- a/course/format/scorm/format.php
+++ b/course/format/scorm/format.php
@@ -25,7 +25,7 @@
     echo '<tr>';
 
     if (blocks_have_content($pageblocks, BLOCK_POS_LEFT) || $editing) {
-        echo '<td width="'.$preferred_width_left.'" id="left-column">';
+        echo '<td style="width:'.$preferred_width_left.'px" id="left-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_LEFT);
         echo '</td>';
     }
@@ -41,7 +41,7 @@
 
     // The right column
     if (blocks_have_content($pageblocks, BLOCK_POS_RIGHT) || $editing) {
-        echo '<td width="'.$preferred_width_right.'" id="right-column">';
+        echo '<td style="width:'.$preferred_width_right.'px" id="right-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_RIGHT);
         echo '</td>';
     }
diff --git a/course/format/social/format.php b/course/format/social/format.php
index f97c50347ef..f917e08e651 100644
--- a/course/format/social/format.php
+++ b/course/format/social/format.php
@@ -23,7 +23,7 @@
     echo '<tr>';
 
     if (blocks_have_content($pageblocks, BLOCK_POS_LEFT) || $editing) {
-        echo '<td width="'.$preferred_width_left.'" id="left-column">';
+        echo '<td style="width:'.$preferred_width_left.'px" id="left-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_LEFT);
         echo '</td>';
     }
@@ -51,7 +51,7 @@
 
     // The right column
     if (blocks_have_content($pageblocks, BLOCK_POS_RIGHT) || $editing) {
-        echo '<td width="'.$preferred_width_right.'" id="right-column">';
+        echo '<td style="width:'.$preferred_width_right.'px" id="right-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_RIGHT);
         echo '</td>';
     }
diff --git a/course/format/topics/format.php b/course/format/topics/format.php
index 6862b009745..92616da7beb 100644
--- a/course/format/topics/format.php
+++ b/course/format/topics/format.php
@@ -70,7 +70,7 @@
 /// The left column ...
 
     if (blocks_have_content($pageblocks, BLOCK_POS_LEFT) || $editing) {
-        echo '<td width="'.$preferred_width_left.'" id="left-column">';
+        echo '<td style="width:'.$preferred_width_left.'px" id="left-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_LEFT);
         echo '</td>';
     }
@@ -263,7 +263,7 @@
 
     // The right column
     if (blocks_have_content($pageblocks, BLOCK_POS_RIGHT) || $editing) {
-        echo '<td width="'.$preferred_width_right.'" id="right-column">';
+        echo '<td style="width:'.$preferred_width_right.'px" id="right-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_RIGHT);
         echo '</td>';
     }
diff --git a/course/format/weeks/format.php b/course/format/weeks/format.php
index b6b3657c059..112fc1f9e02 100644
--- a/course/format/weeks/format.php
+++ b/course/format/weeks/format.php
@@ -56,7 +56,7 @@
 /// The left column ...
 
     if (blocks_have_content($pageblocks, BLOCK_POS_LEFT) || $editing) {
-        echo '<td width="'.$preferred_width_left.'" id="left-column">';
+        echo '<td style="width:'.$preferred_width_left.'px" id="left-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_LEFT);
         echo '</td>';
     }
@@ -260,7 +260,7 @@
 
     // The right column
     if (blocks_have_content($pageblocks, BLOCK_POS_RIGHT) || $editing) {
-        echo '<td width="'.$preferred_width_right.'" id="right-column">';
+        echo '<td style="width: '.$preferred_width_right.'px;" id="right-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_RIGHT);
         echo '</td>';
     }