Fix some colors in light theme (mastodon#10754)

* Fix typo in light theme

* Fix background color of empty column

Author: nzws

app/javascript/styles/mastodon-light/diff.scss

@@ -293,7 +293,7 @@ html {
 .actions-modal ul li:not(:empty) a:focus button,
 .actions-modal ul li:not(:empty) a:hover,
 .actions-modal ul li:not(:empty) a:hover button,
-.admin-wrapper .sidebar ul .simple-navigation-active-leaf a,
+.admin-wrapper .sidebar ul li .simple-navigation-active-leaf a,
 .simple_form .block-button,
 .simple_form .button,
 .simple_form button {