Make Print Preview elements transitions smoother.

chrome/browser/resources/print_preview/print_preview.css

Index: chrome/browser/resources/print_preview/print_preview.css
diff --git a/chrome/browser/resources/print_preview/print_preview.css b/chrome/browser/resources/print_preview/print_preview.css
index eb7d94ca2ee15a1af593da37a1ff6c007a612781..1bbb36d239bd3b87c8710a140a2f01d76c39f7a1 100644
--- a/chrome/browser/resources/print_preview/print_preview.css
+++ b/chrome/browser/resources/print_preview/print_preview.css
@@ -78,21 +78,34 @@ header {
   width: 13px;
 }
 
-.two-column h1 {
+.left-column {
   -webkit-padding-end: 20px;
   -webkit-padding-start: 20px;
-  color: #646464;
   display: table-cell;
-  font-size: 12px;
   min-width: 70px;
+  vertical-align: middle;
 }
 
-.two-column.visible h1,
+.left-column h1 {
+  -webkit-margin-after: 0;
+  -webkit-margin-before: 0;
+  color: #646464;
+  font-size: 12px;
+}
+
+.two-column.visible .left-column,
 .two-column.visible .right-column {
   padding-bottom: 5px;
   padding-top: 5px;
 }
 
+.two-column:not(.visible) .left-column,
+.two-column:not(.visible) .right-column {
+  -webkit-transition: padding-bottom 150ms, padding-top 150ms;
+  padding-bottom: 0;
+  padding-top: 0;
+}
+
 .two-column:not(.visible) select {
   border-top-width: 0;
   margin-top: 0;
@@ -174,6 +187,7 @@ span.hint.closing {
 
 .collapsible {
   height: 0;
+  position: relative;
 }
 
 .collapsible.visible {
@@ -189,6 +203,10 @@ span.hint.closing {
   overflow: hidden;
 }
 
+.collapsible.closing > * {
+  position: absolute;
+}
+
 select {
   width: 100%;
 }