diff --git a/toolkit/content/aboutTelemetry.css b/toolkit/content/aboutTelemetry.css
index 16969254e825..ee9273a03f13 100644
--- a/toolkit/content/aboutTelemetry.css
+++ b/toolkit/content/aboutTelemetry.css
@@ -241,7 +241,7 @@ section:not(.active) {
 }
 
 .histogram {
-  float: left;
+  float: inline-start;
   white-space: nowrap;
   padding: 10px;
   position: relative; /* required for position:absolute of the contained .copy-node */
@@ -253,11 +253,6 @@ section:not(.active) {
   min-height: 17.5em;
 }
 
-
-body:dir(rtl) .histogram {
-  float: right;
-}
-
 .histogram-title {
   text-overflow: ellipsis;
   width: 100%;
@@ -294,14 +289,10 @@ body:dir(rtl) .histogram {
   width: 2em;
   margin: 2px;
   text-align: center;
-  float: left;
+  float: inline-start;
   font-family: monospace;
 }
 
-body:dir(rtl) .bar {
-  float: right;
-}
-
 .bar-inner {
   background-color: #0a84ff;
   border: 1px solid #0060df;
diff --git a/toolkit/themes/osx/global/dirListing/dirListing.css b/toolkit/themes/osx/global/dirListing/dirListing.css
index de881a5e4bb0..1a5eee9cd012 100644
--- a/toolkit/themes/osx/global/dirListing/dirListing.css
+++ b/toolkit/themes/osx/global/dirListing/dirListing.css
@@ -42,20 +42,12 @@ p {
 
 #UI_goUp {
   margin-top: 0;
-  float: left;
-}
-
-#UI_goUp:dir(rtl) {
-  float: right;
+  float: inline-start;
 }
 
 #UI_showHidden {
   margin-top: 0;
-  float: right;
-}
-
-#UI_showHidden:dir(rtl) {
-  float: left;
+  float: inline-end;
 }
 
 table {
diff --git a/toolkit/themes/shared/aboutNetworking.css b/toolkit/themes/shared/aboutNetworking.css
index 82bf4b1df529..dd40610f68aa 100644
--- a/toolkit/themes/shared/aboutNetworking.css
+++ b/toolkit/themes/shared/aboutNetworking.css
@@ -15,11 +15,7 @@ body {
 }
 
 #sectionTitle {
-  float: left;
-}
-
-#sectionTitle:dir(rtl) {
-  float: right;
+  float: inline-start;
 }
 
 #refreshDiv {
diff --git a/toolkit/themes/shared/aboutProfiles.css b/toolkit/themes/shared/aboutProfiles.css
index 5949032b09cb..60e6599a861a 100644
--- a/toolkit/themes/shared/aboutProfiles.css
+++ b/toolkit/themes/shared/aboutProfiles.css
@@ -19,14 +19,10 @@ button {
 }
 
 #action-box {
-  float: right;
+  float: inline-end;
   margin-top: 2em;
   margin-bottom: 20px;
   margin-inline-start: 20px;
   margin-inline-end: 0;
   width: 30%;
 }
-
-#action-box:dir(rtl) {
-  float: left;
-}
diff --git a/toolkit/themes/shared/aboutSupport.css b/toolkit/themes/shared/aboutSupport.css
index d7a97cf99063..c894bb2273e8 100644
--- a/toolkit/themes/shared/aboutSupport.css
+++ b/toolkit/themes/shared/aboutSupport.css
@@ -64,7 +64,7 @@ td.integer {
 }
 
 #action-box {
-  float: right;
+  float: inline-end;
   margin-top: 2em;
   margin-bottom: 20px;
   margin-inline-start: 20px;
@@ -78,10 +78,6 @@ td.integer {
   display: none;
 }
 
-#action-box:dir(rtl) {
-  float: left;
-}
-
 #reset-box > h3 {
   margin-top: 0;
 }
diff --git a/toolkit/themes/windows/global/dirListing/dirListing.css b/toolkit/themes/windows/global/dirListing/dirListing.css
index 8677caf306b9..7accc2e5254a 100644
--- a/toolkit/themes/windows/global/dirListing/dirListing.css
+++ b/toolkit/themes/windows/global/dirListing/dirListing.css
@@ -42,20 +42,12 @@ p {
 
 #UI_goUp {
   margin-top: 0;
-  float: left;
-}
-
-#UI_goUp:dir(rtl) {
-  float: right;
+  float: inline-start;
 }
 
 #UI_showHidden {
   margin-top: 0;
-  float: right;
-}
-
-#UI_showHidden:dir(rtl) {
-  float: left;
+  float: inline-end;
 }
 
 table {