diff --git a/apps/theming/css/default.css b/apps/theming/css/default.css
index 5ed4b5b2739c3..34bf225109509 100644
--- a/apps/theming/css/default.css
+++ b/apps/theming/css/default.css
@@ -49,6 +49,9 @@
   --default-font-size: 15px;
   --animation-quick: 100ms;
   --animation-slow: 300ms;
+  /** Border width for input elements such as text fields and selects */
+  --border-width-input: 1px;
+  --border-width-input-focused: 2px;
   --border-radius: 3px;
   --border-radius-large: 10px;
   --border-radius-rounded: 28px;
diff --git a/apps/theming/lib/Themes/DefaultTheme.php b/apps/theming/lib/Themes/DefaultTheme.php
index 38b76d158b4d8..19d1f2834281f 100644
--- a/apps/theming/lib/Themes/DefaultTheme.php
+++ b/apps/theming/lib/Themes/DefaultTheme.php
@@ -186,6 +186,9 @@ public function getCSSVariables(): array {
 			'--animation-slow' => '300ms',
 
 			// Default variables --------------------------------------------
+			// Border width for input elements such as text fields and selects
+			'--border-width-input' => '1px',
+			'--border-width-input-focused' => '2px',
 			'--border-radius' => '3px',
 			'--border-radius-large' => '10px',
 			'--border-radius-rounded' => '28px',