diff --git a/IPython/html/static/base/less/flexbox.less b/IPython/html/static/base/less/flexbox.less
index a032198..510e27b 100644
--- a/IPython/html/static/base/less/flexbox.less
+++ b/IPython/html/static/base/less/flexbox.less
@@ -128,22 +128,22 @@
 }
 
 .align-start {
-	-webkit-box-align: start;
-	-moz-box-align: start;
-	box-align: start;
+    -webkit-box-align: start;
+    -moz-box-align: start;
+    box-align: start;
     align-content: flex-start;
 }
 
 .align-end {
-	-webkit-box-align: end;
-	-moz-box-align: end;
-	box-align: end;
+    -webkit-box-align: end;
+    -moz-box-align: end;
+    box-align: end;
     align-content: flex-end;
 }
 
 .align-center {
-	-webkit-box-align: center;
-	-moz-box-align: center;
-	box-align: center;
+    -webkit-box-align: center;
+    -moz-box-align: center;
+    box-align: center;
     align-content: center;
 }