update packages and add valign

scripts/reveal.js/css/theme/serif.scss

@@ -0,0 +1,44 @@
+/**
+ * A simple theme for reveal.js presentations, similar
+ * to the default theme. The accent color is brown.
+ *
+ * This theme is Copyright (C) 2012-2013 Owen Versteeg, http://owenversteeg.com - it is MIT licensed.
+ */
+
+// Load utils
+@use 'sass:color';
+@use 'template/mixins' as mixins;
+
+$active-color: #51483d;
+
+// Inject theme variables (with some overrides)
+@use 'template/settings' with (
+	$background-color: #f0f1eb,
+
+	$main-font: "'Palatino Linotype', 'Book Antiqua', Palatino, FreeSerif, serif",
+	$main-font-size: 42px,
+	$main-color: #000,
+
+	$heading-color: #383d3d,
+	$heading-font: "'Palatino Linotype', 'Book Antiqua', Palatino, FreeSerif, serif",
+	$heading-font-weight: 600,
+	$heading-text-transform: none,
+
+	$link-color: $active-color,
+	$link-color-hover: color.scale($active-color, $lightness: 25%),
+	$selection-color: #fff,
+	$selection-background-color: $active-color,
+
+	$overlay-element-bg-color: '0 0 0',
+	$overlay-element-fg-color: '240 240 240'
+);
+
+// Inject the theme template
+@use 'template/theme';
+
+// Change text colors against light slide backgrounds
+@include mixins.dark-bg-text-color(#fff);
+
+.reveal a {
+	line-height: 1.3em;
+}