diff --git a/layout/style/res/forms.css b/layout/style/res/forms.css
index 88c26e4ea3820248044d9b217ace5fe61085431f..70aaf63e933530c8cd5bf1da3e5ef3f167f4c77d 100644
--- a/layout/style/res/forms.css
+++ b/layout/style/res/forms.css
@@ -274,7 +274,7 @@ select[size="1"] {
   background-color: -moz-Combobox;
   color: -moz-ComboboxText;
   vertical-align: baseline;
-  padding: 0;
+  padding: unset;
   -moz-appearance: menulist;
 }
 
@@ -331,9 +331,9 @@ select:empty {
   padding-block-end: 1px;
   padding-inline-start: 4px;
   padding-inline-end: 0;
-  color: inherit;
+  color: unset;
   white-space: nowrap;
-  text-align: inherit;
+  text-align: unset;
   -moz-user-select: none;
   /* Make sure to size correctly if the combobox has a non-auto block-size. */
   block-size: 100% ! important;
@@ -380,7 +380,7 @@ optgroup {
   line-height: normal !important;
   font-style: italic;
   font-weight: bold;
-  font-size: inherit;
+  font-size: unset;
   -moz-user-select: none;
   text-indent: 0;
   white-space: nowrap !important;
@@ -432,7 +432,7 @@ select:disabled:disabled /* Need the pseudo-class twice to have the specificity
 {
   color: GrayText;
   background-color: ThreeDLightShadow;
-  cursor: inherit;
+  cursor: unset;
 }
 
 input:disabled,
@@ -449,7 +449,7 @@ optgroup:disabled {
 input[type="hidden"] {
   -moz-appearance: none;
   display: none !important;
-  padding: 0;
+  padding: unset;
   border: 0;
   cursor: auto;
   -moz-user-focus: ignore;
@@ -459,7 +459,7 @@ input[type="hidden"] {
 /* image buttons */
 input[type="image"] {
   -moz-appearance: none;
-  padding: 0;
+  padding: unset;
   border: none;
   background-color: transparent;
   font-family: sans-serif;
@@ -469,7 +469,7 @@ input[type="image"] {
 }
 
 input[type="image"]:disabled {
-  cursor: inherit;
+  cursor: unset;
 }
 
 input[type="image"]:-moz-focusring {
@@ -483,7 +483,7 @@ input[type="file"] {
   white-space: nowrap;
   overflow: hidden;
   overflow-clip-box: padding-box;
-  color: inherit;
+  color: unset;
 
   /* Revert rules which apply on all inputs. */
   -moz-appearance: none;
@@ -492,7 +492,7 @@ input[type="file"] {
 
   border: none;
   background-color: transparent;
-  padding: 0;
+  padding: unset;
 }
 
 input[type="file"] > xul|label {
@@ -500,9 +500,9 @@ input[type="file"] > xul|label {
   padding-inline-start: 5px;
   text-align: match-parent;
 
-  color: inherit;
-  font-size: inherit;
-  letter-spacing: inherit;
+  color: unset;
+  font-size: unset;
+  letter-spacing: unset;
 
   /*
    * Force the text to have LTR directionality. Otherwise filenames containing
@@ -514,9 +514,9 @@ input[type="file"] > xul|label {
 /* button part of file selector */
 input[type="file"] > button[type="button"] {
   block-size: inherit;
-  font-size: inherit;
-  letter-spacing: inherit;
-  cursor: inherit;
+  font-size: unset;
+  letter-spacing: unset;
+  cursor: unset;
 }
 
 /* colored part of the color selector button */
@@ -582,7 +582,7 @@ input[type="checkbox"]:disabled,
 input[type="checkbox"]:disabled:active,
 input[type="checkbox"]:disabled:hover,
 input[type="checkbox"]:disabled:hover:active {
-  cursor: inherit;
+  cursor: unset;
 }
 
 % On Mac, the native theme takes care of this.
@@ -649,7 +649,7 @@ input[type="color"] {
 
 button {
   /* Buttons should lay out like "normal" html, mostly */
-  white-space: inherit;
+  white-space: unset;
   text-indent: 0;
   /* But no text-decoration reaching inside, by default */
   display: inline-block;
@@ -767,7 +767,7 @@ input[type="submit"]:disabled {
   padding-block-end: 0px;
   padding-inline-start: 8px;
   border: 2px outset ThreeDLightShadow;
-  cursor: inherit;
+  cursor: unset;
 }
 
 button:disabled:active, button:disabled,
@@ -1058,12 +1058,12 @@ input[type=number]::-moz-number-text {
    * above. We want to inherit its value from its <input type=number>
    * ancestor, not have that general CSS rule reset it.
    */
-  text-align: inherit;
+  text-align: unset;
   text-decoration: inherit;
   ime-mode: inherit;
   flex: 1;
   min-inline-size: 0;
-  padding: 0;
+  padding: unset;
   border: 0;
   margin: 0;
 }
diff --git a/layout/style/res/html.css b/layout/style/res/html.css
index 2f553d3391b549f1e8da89fc88ab16ad457fe7cd..8a74108b89c9fd9da98aafa9901ef2d6ff0533c3 100644
--- a/layout/style/res/html.css
+++ b/layout/style/res/html.css
@@ -472,7 +472,7 @@ table > tr {
 td { 
   display: table-cell;
   vertical-align: inherit;
-  text-align: inherit; 
+  text-align: unset; 
   padding: 1px;
 }
 
@@ -729,7 +729,7 @@ area {
 iframe:fullscreen {
   /* iframes in full-screen mode don't show a border. */
   border: none !important;
-  padding: 0 !important;
+  padding: unset !important;
 }
 
 /* media elements */
@@ -899,7 +899,7 @@ rtc:lang(zh-TW), rt:lang(zh-TW) {
   -moz-min-font-size-ratio: 30%;
 }
 rtc > rt {
-  font-size: inherit;
+  font-size: unset;
 }
 ruby, rb, rt, rtc {
   unicode-bidi: isolate;
diff --git a/layout/style/res/quirk.css b/layout/style/res/quirk.css
index ba9e6d4acee9762f08a870da8366ed800dded434..daf01098fa295fd3b14720d217f266e123b1d980 100644
--- a/layout/style/res/quirk.css
+++ b/layout/style/res/quirk.css
@@ -22,7 +22,7 @@ li ul, li ol, li dir, li menu {
   ol ul,   ol ol,   ol dir,   ol menu,   ol li,
  dir ul,  dir ol,  dir dir,  dir menu,  dir li,
 menu ul, menu ol, menu dir, menu menu, menu li {
-  list-style-position: inherit;
+  list-style-position: unset;
 }