wip fix vertical alignment

Author: gnprice

lib/widgets/message_list.dart

@@ -481,6 +481,10 @@ class DateSeparator extends StatelessWidget {
   Widget build(BuildContext context) {
     final zulipLocalizations = ZulipLocalizations.of(context);
 
+    // This makes the small-caps text vertically centered,
+    // to align with the vertically centered divider lines.
+    const textBottomPadding = 2.0;
+
     return ColoredBox(color: Colors.white,
       child: Padding(
         padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 2),
@@ -493,17 +497,14 @@ class DateSeparator extends StatelessWidget {
                     bottom: BorderSide(
                       width: 0,
                       color: Colors.black)))))),
-          Padding(padding: const EdgeInsets.symmetric(horizontal: 2),
+          Padding(padding: const EdgeInsets.fromLTRB(2, 0, 2, textBottomPadding),
             // TODO dedupe with RecipientHeaderDate
             child: Text(
               style: TextStyle(
                 color: _textColor,
                 fontFamily: 'Source Sans 3',
                 fontSize: 16,
-                // In Figma this has a line-height of 19, but using 18
-                // here to match the stream/topic text widgets helps
-                // to align all the text to the same baseline.
-                height: (18 / 16),
+                height: (16 / 16),
                 // This is equivalent to css `all-small-caps`, see:
                 //   https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-caps#all-small-caps
                 fontFeatures: const [FontFeature.enable('c2sc'), FontFeature.enable('smcp')],