diff --git a/Themes/default/css/admin.css b/Themes/default/css/admin.css
index 0b21abce68..beed01452f 100644
--- a/Themes/default/css/admin.css
+++ b/Themes/default/css/admin.css
@@ -421,7 +421,7 @@ fieldset.qa_fieldset {
 span.search_weight {
 	width: 40px;
 	padding: 0 0.5em;
-	text-align: right;
+	text-align: end;
 }
 .search_settings {
 	width: 47%;
diff --git a/Themes/default/css/calendar.css b/Themes/default/css/calendar.css
index 45053d1a74..36c3aad52b 100644
--- a/Themes/default/css/calendar.css
+++ b/Themes/default/css/calendar.css
@@ -21,7 +21,7 @@ td.days:hover {
 }
 #month_grid {
 	width: 214px;
-	float: left;
+	float: inline-start;
 	text-align: center;
 	overflow: hidden;
 	margin-right: 10px;
@@ -85,7 +85,7 @@ td.days:hover {
 #main_grid th.days {
 	width: 14%;
 	padding: 5px 10px;
-	text-align: left;
+	text-align: start;
 	background: var(--calendar-th-bg);
 }
 #main_grid td.weeks {
@@ -135,7 +135,7 @@ td.days:hover {
 #main_grid td.days,
 #month_grid td.days {
 	vertical-align: top;
-	text-align: left;
+	text-align: start;
 	border-right: 1px solid var(--window-border-color);
 	border-bottom: 1px solid var(--window-border-color);
 }
diff --git a/Themes/default/css/calendar.rtl.css b/Themes/default/css/calendar.rtl.css
index 976b0be219..692550c25a 100644
--- a/Themes/default/css/calendar.rtl.css
+++ b/Themes/default/css/calendar.rtl.css
@@ -4,7 +4,6 @@
 	margin: 0 0 0 2px;
 }
 #month_grid {
-	float: right;
 	margin: 0 0 0 1%;
 }
 #main_grid table.weeklist td.windowbg {
diff --git a/Themes/default/css/index.css b/Themes/default/css/index.css
index 32c170b33c..0c2ec345b6 100644
--- a/Themes/default/css/index.css
+++ b/Themes/default/css/index.css
@@ -1255,7 +1255,7 @@ html[lang="el-GR"] .inline_mod_check {
 	height: 18px;
 	width: 18px;
 	margin: 2px 5px 0 0;
-	float: left;
+	float: inline-start;
 }
 #pm_menu_top .main_icons,
 #alerts_menu_top .main_icons {
@@ -1532,7 +1532,7 @@ ul li.greeting {
 }
 .mark_read {
 	margin: -5px 0 16px 0;
-	float: right;
+	float: inline-end;
 }
 .mark_read .buttonlist {
 	margin: 0;
@@ -1787,7 +1787,7 @@ ul li.greeting {
 .move_topic {
 	width: 710px;
 	margin: auto;
-	text-align: left;
+	text-align: start;
 }
 div.move_topic fieldset {
 	margin-top: 1ex;
@@ -1854,7 +1854,7 @@ fieldset.merge_options {
 	padding: 1px;
 }
 .login dt {
-	float: left;
+	float: inline-start;
 	clear: both;
 	text-align: right;
 	font-weight: bold;
@@ -1862,7 +1862,7 @@ fieldset.merge_options {
 .login dd {
 	width: 54%;
 	float: right;
-	text-align: left;
+	text-align: start;
 }
 .login p {
 	text-align: center;
@@ -1890,7 +1890,7 @@ dl.register_form {
 }
 dl.register_form dt {
 	font-weight: normal;
-	float: left;
+	float: inline-start;
 	clear: both;
 	width: 50%;
 	margin: 6px 0 0 0;
@@ -2378,7 +2378,7 @@ a.main_icons.feed::before {
 .errorbox p.alert {
 	padding: 0;
 	margin: 0 4px 0 0;
-	float: left;
+	float: inline-start;
 	width: 12px;
 	font-size: 1.5em;
 }
@@ -2497,14 +2497,14 @@ dl {
 
 /* View posts */
 .topic .time {
-	float: right;
+	float: inline-end;
 }
 .counter {
 	padding: 5px 6px 1px 2px;
 	font-size: 2.2em;
 	font-weight: bold;
 	color: var(--counter-color);
-	float: left;
+	float: inline-start;
 }
 .topic_details {
 	padding: 0 4px 4px 4px;
@@ -2605,7 +2605,7 @@ dl {
 /* Pick theme */
 #pick_theme {
 	width: 100%;
-	float: left;
+	float: inline-start;
 }
 #pick_theme .selected {
 	background: var(--picktheme-selected-bg);
@@ -2620,7 +2620,7 @@ dl {
 }
 dl.stats dt {
 	width: 50%;
-	float: left;
+	float: inline-start;
 	margin: 0 0 4px 0;
 	line-height: 1.5em;
 	clear: both;
@@ -2646,12 +2646,12 @@ dl.stats {
 	text-align: center;
 }
 #stats tr.windowbg th.lefttext {
-	text-align: left;
+	text-align: start;
 }
 #stats tr.windowbg th.stats_month {
 	width: 25%;
 	padding: 0 2em;
-	text-align: left;
+	text-align: start;
 }
 #stats tr.windowbg td.stats_day {
 	padding: 0 3.5em;
@@ -2716,7 +2716,7 @@ dl.addrules dt.floatleft {
 	clear: both;
 }
 #to_item_list_container div, #bcc_item_list_container div {
-	float: left;
+	float: inline-start;
 	margin-right: 10px;
 }
 .unread_pm {
@@ -2789,7 +2789,7 @@ dl.addrules dt.floatleft {
 /* Styles for the search section.
 ------------------------------------------------- */
 #searchform fieldset {
-	text-align: left;
+	text-align: start;
 	padding: 0;
 	border: none;
 }
@@ -2817,15 +2817,15 @@ dl.addrules dt.floatleft {
 }
 #advanced_search dt {
 	padding: 2px;
-	text-align: right;
+	text-align: end;
 	width: 20%;
 }
 #advanced_search dd {
 	width: 75%;
-	float: left;
+	float: inline-start;
 	padding: 2px;
 	margin: 0 0 0 6px;
-	text-align: left;
+	text-align: start;
 }
 #search_results {
 	margin-bottom: 5px;
@@ -3079,7 +3079,7 @@ div#manage_boards dl dd textarea[name=desc] {
 	margin-bottom: 15px;
 }
 h3 .collapse {
-	float: right;
+	float: inline-end;
 	margin: 4px 4px 0 0;
 }
 .board_icon a {
@@ -3338,7 +3338,7 @@ span.postby {
 	padding: 4px 0;
 	width: 30%;
 	max-width: 30em;
-	float: left;
+	float: inline-start;
 	clear: left;
 }
 #poll_options dl.options .voted {
@@ -3347,9 +3347,9 @@ span.postby {
 #poll_options dl.options dd {
 	width: 60%;
 	max-width: 45em;
-	float: left;
+	float: inline-start;
 	margin: 0 0 4px 0;
-	text-align: right;
+	text-align: end;
 }
 
 /* Poll notices */
@@ -3406,7 +3406,7 @@ div#pollmoderation {
 }
 /* poster details and list of items */
 .poster {
-	float: left;
+	float: inline-start;
 	/* Don't set this in em.It will eat too much space if people need to set large text sizes. */
 	width: 160px;
 	-webkit-hyphens: auto;
@@ -3620,7 +3620,15 @@ form#postmodify .roundframe {
 	padding: 6px;
 	overflow: hidden;
 }
-#post_header dt,
+#post_header dt {
+	float: inline-start;
+	padding: 0;
+	width: 15%;
+	margin: 6px 0 0 0;
+	font-weight: bold;
+}
+/* The event editor is not mirrored for right-to-left yet, so this half of
+   the pair keeps a physical float until it is. */
 #event_options dt {
 	float: left;
 	padding: 0;
@@ -3628,7 +3636,14 @@ form#postmodify .roundframe {
 	margin: 6px 0 0 0;
 	font-weight: bold;
 }
-#post_header dd,
+#post_header dd {
+	float: inline-start;
+	padding: 0;
+	width: 83%;
+	margin: 4px 0;
+}
+/* The event editor is not mirrored for right-to-left yet, so this half of
+   the pair keeps a physical float until it is. */
 #event_options dd {
 	float: left;
 	padding: 0;
@@ -3751,7 +3766,7 @@ form#postmodify .roundframe {
 	float: left;
 }
 #moderationbuttons_strip {
-	float: left;
+	float: inline-start;
 	margin: 4px 0 4px;
 }
 #moderationbuttons ul li {
diff --git a/Themes/default/css/profile.css b/Themes/default/css/profile.css
index 8a43434043..4c89a3c779 100644
--- a/Themes/default/css/profile.css
+++ b/Themes/default/css/profile.css
@@ -14,12 +14,12 @@
 /* The basic user info on the left */
 #basicinfo {
 	width: 20%;
-	float: left;
+	float: inline-start;
 }
 
 #detailedinfo {
 	width: 79.5%;
-	float: right;
+	float: inline-end;
 }
 
 #basicinfo > * {
@@ -47,7 +47,7 @@
 
 #basicinfo .icon_fields li {
 	display: block;
-	float: left;
+	float: inline-start;
 	margin-right: 5px;
 	height: 20px;
 }
@@ -96,7 +96,7 @@
 }
 
 #avatar_server_stored div {
-	float: left;
+	float: inline-start;
 }
 
 #avatar_upload {
@@ -122,7 +122,7 @@
 
 .activity_stats li {
 	width: 4.16%;
-	float: left;
+	float: inline-start;
 	text-align: center;
 }
 
@@ -155,7 +155,7 @@
 .profile_pie {
 	background: url(../images/stats_pie.png);
 	background-size: auto 20px;
-	float: left;
+	float: inline-start;
 	height: 20px;
 	width: 20px;
 	margin: 0 12px 0 0;
diff --git a/Themes/default/css/rtl.css b/Themes/default/css/rtl.css
index 1be7dec6ad..24f83dca31 100644
--- a/Themes/default/css/rtl.css
+++ b/Themes/default/css/rtl.css
@@ -106,7 +106,6 @@ img#smflogo {
 
 /* Profile drop it needs reverse on RTL */
 #profile_menu_top > img.avatar {
-	float: right;
 	margin: 2px 0 0 5px;
 }
 #profile_menu .profile_user_info {
@@ -125,34 +124,14 @@ img#smflogo {
 	text-align: left;
 }
 
-/* the posting icons */
-#postbuttons_upper ul li a span {
-	line-height: 19px;
-	padding: 0 6px 0 0;
-}
-
-.mark_read {
-	float: left;
-}
-
 /* Poll results */
 #poll_options dl.options {
 	padding: 1em 2em 1em 2.5em;
 	margin: 0 0 1em 1em;
 }
 #poll_options dl.options dt {
-	float: right;
 	clear: right;
 }
-#poll_options dl.options dd {
-	float: right;
-	text-align: left;
-}
-
-/* poster and postarea + moderation area underneath */
-.poster {
-	float: right;
-}
 .postarea, .moderatorbar {
 	margin: 0 175px 0 0;
 }
@@ -213,15 +192,6 @@ ul.quickbuttons li {
 #forumposts .modified {
 	float: right;
 }
-#forumposts .reportlinks {
-	margin-left: 1.5em;
-	text-align: left;
-	clear: left;
-}
-
-#moderationbuttons_strip {
-	float: right;
-}
 #moderationbuttons_strip ul {
 	margin: 0 0.2em 0 0;
 	padding: 0 1em 0 0;
@@ -239,38 +209,6 @@ ul.quickbuttons li {
 	width: 80px;
 }
 
-/* Styles for edit post section
----------------------------------------------------- */
-#post_header dt {
-	float: right;
-}
-#post_header dd {
-	float: right;
-}
-
-/* Styles for edit event section
----------------------------------------------------- */
-#post_event div.event_options {
-	float: left;
-}
-#post_event #event_main input {
-	margin: 0 0 1em 0;
-	float: right;
-}
-#post_event #event_main div.smalltext {
-	float: left;
-}
-#post_event ul.event_main li {
-	float: left;
-}
-#post_event ul.event_options {
-	padding: 0 .7em .7em 0;
-}
-#post_event #event_main select, #post_event ul.event_options li select,
-#post_event ul.event_options li input[type="checkbox"] {
-	margin: 0 0 0 1em;
-}
-
 /* Styles for edit poll section.
 ---------------------------------------------------- */
 #edit_poll fieldset input {
@@ -297,36 +235,14 @@ ul.quickbuttons li {
 
 /* Styles for the personal messages section.
 ------------------------------------------------- */
-#personal_messages h3 span#author, #personal_messages h3 span#topic_title {
-	float: right;
-}
-#personal_messages h3 span#author {
-	margin: 0 0.5em 0 0;
-}
-#personal_messages h3 span#topic_title {
-	margin: 0 9em 0 0;
-}
 #personal_messages .labels {
 	padding: 0 0 0 1em;
 }
 #to_item_list_container div, #bcc_item_list_container div {
-	float: right;
 	margin: 0;
 }
-
-/* Styles for the move topic section. */
-.move_topic {
-	text-align: right;
-}
-
-/* Styles for the login areas.
-------------------------------------------------------- */
-.login dt {
-	float: right;
-}
 .login dd {
 	float: right;
-	text-align: right;
 }
 .login h3 img {
 	margin: 0 0 0.5em;
@@ -337,10 +253,6 @@ dl.register_form {
 	clear: left;
 }
 
-dl.register_form dt {
-	float: right;
-}
-
 /* Styles for maintenance mode.
 ------------------------------------------------------- */
 #maintenance_mode img.floatleft {
@@ -380,28 +292,15 @@ div#admin_menu {
 }
 .errorbox p.alert {
 	margin: 0 0 0 4px;
-	float: right;
 }
 .errorbox, .noticebox, .infobox {
 	padding: 7px 35px 7px 10px;
 }
 
-/* Styles for the profile section.
-------------------------------------------------- */
-#basicinfo {
-	float: right;
-}
-#detailedinfo {
-	float: left;
-}
 #basicinfo .icon_fields li {
-	float: right;
 	margin-right: 0;
 	margin-left: 5px;
 }
-#avatar_server_stored div {
-	float: right;
-}
 #detailedinfo dt, #tracking dt {
 	float: right;
 }
@@ -409,10 +308,6 @@ div#admin_menu {
 	margin: 0 5px 0 0 !important;
 }
 /* h3 HD Icons */
-h3.search_hd {
-	padding: 8px 45px 6px;
-	background-position: 99% 50%;
-}
 h3.profile_hd {
 	padding: 8px 50px 8px 0;
 	background-position: 99% 50%;
@@ -422,9 +317,6 @@ h3.profile_hd {
 #activitytime {
 	clear: right;
 }
-.activity_stats li {
-	float: right;
-}
 .activity_stats li span {
 	border-width: 1px 0 0 1px;
 }
@@ -433,31 +325,11 @@ h3.profile_hd {
 }
 .profile_pie {
 	background-image: url(../images/stats_pie_rtl.png);
-	float: right;
 	margin-right: 0;
 	margin-left: 1em;
 }
-
-/* Most popular boards by posts and activity */
-#popularposts {
-	float: right;
-}
-#popularactivity {
-	float: left;
-}
-
-/* View posts */
-.topic .time {
-	float: left;
-}
 .counter {
 	padding: 0.2em 0.2em 0.1em 0.5em;
-	float: right;
-}
-.topic .mod_icons {
-	text-align: left;
-	margin-right: 0;
-	margin-left: 1em;
 }
 
 #ip_list li.header, #ip_list li.ip {
@@ -476,29 +348,13 @@ h3.profile_hd {
 .ignoreboards li {
 	float: right;
 }
-
-#pick_theme {
-	float: right;
-}
 .infolinks {
 	min-width: 95%;
 	float: right;
 }
-
-/* Styles for the statistics center.
-------------------------------------------------- */
-.stats_icon {
-	margin: 2px 3px -1px 6px;
-}
-dl.stats dt {
-	float: right;
-}
 dl.stats dd {
 	margin: 0 2% 4px 0;
 }
-#stats tr.windowbg th.stats_month {
-	text-align: right;
-}
 .generic_bar .bar, .progress_bar .bar {
 	left: unset;
 	right: 0;
@@ -506,38 +362,25 @@ dl.stats dd {
 tr.windowbg th.stats_month, tr.windowbg td.stats_day {
 	text-align: right;
 }
-#stats tr.windowbg th.lefttext, #stats tr.titlebg th.lefttext {
+/* Only the windowbg half of this pair has a left-to-right rule to mirror;
+   the titlebg half is aligned by .lefttext, so it still needs flipping here. */
+#stats tr.titlebg th.lefttext {
 	text-align: right;
 }
 
-/* Styles for the advanced search section.
-------------------------------------------------- */
-#searchform fieldset {
-	text-align: right;
-}
 #advanced_search dt {
 	float: right;
-	text-align: left;
 }
 #advanced_search dd {
-	float: right;
 	margin: 0 0.5em 0 0;
-	text-align: right;
 }
 /* Boards picker */
 #searchform fieldset p {
 	text-align: right;
 }
 
-.search_results_posts .buttons {
-	padding: 5px 0 0 1em;
-}
-
 /* Styles for the help section.
 ------------------------------------------------- */
-#helpmain h3.section {
-	padding: 0 0.5em 0.5em 0;
-}
 /* put back the bullets please */
 #helpmain ul {
 	margin: 0 25px 0 0;
@@ -579,10 +422,6 @@ tr.windowbg th.stats_month, tr.windowbg td.stats_day {
 	padding: 0 0 0 13px;
 }
 
-span.search_weight {
-	text-align: left;
-}
-
 /* Manage Bans */
 .ban_restriction {
 	margin: 0.2em 2.2em 0.2em 0;
@@ -603,21 +442,11 @@ ul.moderation_notes li {
 	padding: 4px 4px 4px 0;
 }
 
-h3 .collapse {
-	float: left;
-}
-
 .pages {
 	margin-left: 0;
 	margin-right: 7px;
 }
 
-/* Styles for the calendar.
------------------------------ */
-#main_grid th.days, #main_grid td.days {
-	text-align: right;
-}
-
 /* Code is a code do it LTR */
 code.bbc_code, pre.file_content {
 	text-align: left;