diff --git a/browser/components/newtab/.stylelintrc.yaml b/browser/components/newtab/.stylelintrc.yaml
index f1b816961d2b..922bba93d3f3 100644
--- a/browser/components/newtab/.stylelintrc.yaml
+++ b/browser/components/newtab/.stylelintrc.yaml
@@ -22,6 +22,7 @@ rules:
   declaration-block-no-duplicate-properties:
     - true
     - severity: error
+  declaration-block-no-redundant-longhand-properties: null
   declaration-no-important:
     - true
     - severity: error
diff --git a/browser/components/newtab/content-src/components/DiscoveryStreamBase/_DiscoveryStreamBase.scss b/browser/components/newtab/content-src/components/DiscoveryStreamBase/_DiscoveryStreamBase.scss
index 623c2b5532c0..015cb57a8b57 100644
--- a/browser/components/newtab/content-src/components/DiscoveryStreamBase/_DiscoveryStreamBase.scss
+++ b/browser/components/newtab/content-src/components/DiscoveryStreamBase/_DiscoveryStreamBase.scss
@@ -6,12 +6,14 @@ $ds-width: 936px;
   --gridRowGap: 24px;
 
   grid-template-columns: repeat($columns, 1fr);
-  grid-gap: var(--gridRowGap) var(--gridColumnGap);
+  grid-column-gap: var(--gridColumnGap);
+  grid-row-gap: var(--gridRowGap);
   margin: 0 auto;
 
   @while $columns > 0 {
     .ds-column-#{$columns} {
-      grid-column: auto span $columns;
+      grid-column-start: auto;
+      grid-column-end: span $columns;
     }
 
     $columns: $columns - 1;
diff --git a/browser/components/newtab/content-src/styles/_activity-stream.scss b/browser/components/newtab/content-src/styles/_activity-stream.scss
index f1823f398889..1261b6e91647 100644
--- a/browser/components/newtab/content-src/styles/_activity-stream.scss
+++ b/browser/components/newtab/content-src/styles/_activity-stream.scss
@@ -67,7 +67,8 @@ h2 {
 .actions {
   border-top: $border-secondary;
   display: flex;
-  flex-flow: row wrap;
+  flex-direction: row;
+  flex-wrap: wrap;
   justify-content: flex-start;
   margin: 0;
   padding: 15px 25px 0;
diff --git a/browser/components/newtab/css/activity-stream-linux.css b/browser/components/newtab/css/activity-stream-linux.css
index 4b1dc2f20a7f..0d95750e919c 100644
--- a/browser/components/newtab/css/activity-stream-linux.css
+++ b/browser/components/newtab/css/activity-stream-linux.css
@@ -318,7 +318,8 @@ h2 {
 .actions {
   border-top: 1px solid var(--newtab-border-color);
   display: flex;
-  flex-flow: row wrap;
+  flex-direction: row;
+  flex-wrap: wrap;
   justify-content: flex-start;
   margin: 0;
   padding: 15px 25px 0;
@@ -2531,44 +2532,57 @@ main.has-snippet {
   --gridColumnGap: 48px;
   --gridRowGap: 24px;
   grid-template-columns: repeat(12, 1fr);
-  grid-gap: var(--gridRowGap) var(--gridColumnGap);
+  grid-column-gap: var(--gridColumnGap);
+  grid-row-gap: var(--gridRowGap);
   margin: 0 auto;
 }
 .discovery-stream.ds-layout .ds-column-12 {
-  grid-column: auto span 12;
+  grid-column-start: auto;
+  grid-column-end: span 12;
 }
 .discovery-stream.ds-layout .ds-column-11 {
-  grid-column: auto span 11;
+  grid-column-start: auto;
+  grid-column-end: span 11;
 }
 .discovery-stream.ds-layout .ds-column-10 {
-  grid-column: auto span 10;
+  grid-column-start: auto;
+  grid-column-end: span 10;
 }
 .discovery-stream.ds-layout .ds-column-9 {
-  grid-column: auto span 9;
+  grid-column-start: auto;
+  grid-column-end: span 9;
 }
 .discovery-stream.ds-layout .ds-column-8 {
-  grid-column: auto span 8;
+  grid-column-start: auto;
+  grid-column-end: span 8;
 }
 .discovery-stream.ds-layout .ds-column-7 {
-  grid-column: auto span 7;
+  grid-column-start: auto;
+  grid-column-end: span 7;
 }
 .discovery-stream.ds-layout .ds-column-6 {
-  grid-column: auto span 6;
+  grid-column-start: auto;
+  grid-column-end: span 6;
 }
 .discovery-stream.ds-layout .ds-column-5 {
-  grid-column: auto span 5;
+  grid-column-start: auto;
+  grid-column-end: span 5;
 }
 .discovery-stream.ds-layout .ds-column-4 {
-  grid-column: auto span 4;
+  grid-column-start: auto;
+  grid-column-end: span 4;
 }
 .discovery-stream.ds-layout .ds-column-3 {
-  grid-column: auto span 3;
+  grid-column-start: auto;
+  grid-column-end: span 3;
 }
 .discovery-stream.ds-layout .ds-column-2 {
-  grid-column: auto span 2;
+  grid-column-start: auto;
+  grid-column-end: span 2;
 }
 .discovery-stream.ds-layout .ds-column-1 {
-  grid-column: auto span 1;
+  grid-column-start: auto;
+  grid-column-end: span 1;
 }
 .discovery-stream.ds-layout .ds-column-grid {
   display: grid;
diff --git a/browser/components/newtab/css/activity-stream-mac.css b/browser/components/newtab/css/activity-stream-mac.css
index 934256f27dfe..d57796e28fc5 100644
--- a/browser/components/newtab/css/activity-stream-mac.css
+++ b/browser/components/newtab/css/activity-stream-mac.css
@@ -322,7 +322,8 @@ h2 {
 .actions {
   border-top: 1px solid var(--newtab-border-color);
   display: flex;
-  flex-flow: row wrap;
+  flex-direction: row;
+  flex-wrap: wrap;
   justify-content: flex-start;
   margin: 0;
   padding: 15px 25px 0;
@@ -2535,44 +2536,57 @@ main.has-snippet {
   --gridColumnGap: 48px;
   --gridRowGap: 24px;
   grid-template-columns: repeat(12, 1fr);
-  grid-gap: var(--gridRowGap) var(--gridColumnGap);
+  grid-column-gap: var(--gridColumnGap);
+  grid-row-gap: var(--gridRowGap);
   margin: 0 auto;
 }
 .discovery-stream.ds-layout .ds-column-12 {
-  grid-column: auto span 12;
+  grid-column-start: auto;
+  grid-column-end: span 12;
 }
 .discovery-stream.ds-layout .ds-column-11 {
-  grid-column: auto span 11;
+  grid-column-start: auto;
+  grid-column-end: span 11;
 }
 .discovery-stream.ds-layout .ds-column-10 {
-  grid-column: auto span 10;
+  grid-column-start: auto;
+  grid-column-end: span 10;
 }
 .discovery-stream.ds-layout .ds-column-9 {
-  grid-column: auto span 9;
+  grid-column-start: auto;
+  grid-column-end: span 9;
 }
 .discovery-stream.ds-layout .ds-column-8 {
-  grid-column: auto span 8;
+  grid-column-start: auto;
+  grid-column-end: span 8;
 }
 .discovery-stream.ds-layout .ds-column-7 {
-  grid-column: auto span 7;
+  grid-column-start: auto;
+  grid-column-end: span 7;
 }
 .discovery-stream.ds-layout .ds-column-6 {
-  grid-column: auto span 6;
+  grid-column-start: auto;
+  grid-column-end: span 6;
 }
 .discovery-stream.ds-layout .ds-column-5 {
-  grid-column: auto span 5;
+  grid-column-start: auto;
+  grid-column-end: span 5;
 }
 .discovery-stream.ds-layout .ds-column-4 {
-  grid-column: auto span 4;
+  grid-column-start: auto;
+  grid-column-end: span 4;
 }
 .discovery-stream.ds-layout .ds-column-3 {
-  grid-column: auto span 3;
+  grid-column-start: auto;
+  grid-column-end: span 3;
 }
 .discovery-stream.ds-layout .ds-column-2 {
-  grid-column: auto span 2;
+  grid-column-start: auto;
+  grid-column-end: span 2;
 }
 .discovery-stream.ds-layout .ds-column-1 {
-  grid-column: auto span 1;
+  grid-column-start: auto;
+  grid-column-end: span 1;
 }
 .discovery-stream.ds-layout .ds-column-grid {
   display: grid;
diff --git a/browser/components/newtab/css/activity-stream-windows.css b/browser/components/newtab/css/activity-stream-windows.css
index fb27b4b67a57..f60b71516ff7 100644
--- a/browser/components/newtab/css/activity-stream-windows.css
+++ b/browser/components/newtab/css/activity-stream-windows.css
@@ -318,7 +318,8 @@ h2 {
 .actions {
   border-top: 1px solid var(--newtab-border-color);
   display: flex;
-  flex-flow: row wrap;
+  flex-direction: row;
+  flex-wrap: wrap;
   justify-content: flex-start;
   margin: 0;
   padding: 15px 25px 0;
@@ -2531,44 +2532,57 @@ main.has-snippet {
   --gridColumnGap: 48px;
   --gridRowGap: 24px;
   grid-template-columns: repeat(12, 1fr);
-  grid-gap: var(--gridRowGap) var(--gridColumnGap);
+  grid-column-gap: var(--gridColumnGap);
+  grid-row-gap: var(--gridRowGap);
   margin: 0 auto;
 }
 .discovery-stream.ds-layout .ds-column-12 {
-  grid-column: auto span 12;
+  grid-column-start: auto;
+  grid-column-end: span 12;
 }
 .discovery-stream.ds-layout .ds-column-11 {
-  grid-column: auto span 11;
+  grid-column-start: auto;
+  grid-column-end: span 11;
 }
 .discovery-stream.ds-layout .ds-column-10 {
-  grid-column: auto span 10;
+  grid-column-start: auto;
+  grid-column-end: span 10;
 }
 .discovery-stream.ds-layout .ds-column-9 {
-  grid-column: auto span 9;
+  grid-column-start: auto;
+  grid-column-end: span 9;
 }
 .discovery-stream.ds-layout .ds-column-8 {
-  grid-column: auto span 8;
+  grid-column-start: auto;
+  grid-column-end: span 8;
 }
 .discovery-stream.ds-layout .ds-column-7 {
-  grid-column: auto span 7;
+  grid-column-start: auto;
+  grid-column-end: span 7;
 }
 .discovery-stream.ds-layout .ds-column-6 {
-  grid-column: auto span 6;
+  grid-column-start: auto;
+  grid-column-end: span 6;
 }
 .discovery-stream.ds-layout .ds-column-5 {
-  grid-column: auto span 5;
+  grid-column-start: auto;
+  grid-column-end: span 5;
 }
 .discovery-stream.ds-layout .ds-column-4 {
-  grid-column: auto span 4;
+  grid-column-start: auto;
+  grid-column-end: span 4;
 }
 .discovery-stream.ds-layout .ds-column-3 {
-  grid-column: auto span 3;
+  grid-column-start: auto;
+  grid-column-end: span 3;
 }
 .discovery-stream.ds-layout .ds-column-2 {
-  grid-column: auto span 2;
+  grid-column-start: auto;
+  grid-column-end: span 2;
 }
 .discovery-stream.ds-layout .ds-column-1 {
-  grid-column: auto span 1;
+  grid-column-start: auto;
+  grid-column-end: span 1;
 }
 .discovery-stream.ds-layout .ds-column-grid {
   display: grid;