Add fallback for constrained content width

Support browsers that do not support registering properties yet and,
thus, won't use the global default value.

Author: tf

entry_types/scrolled/package/src/frontend/layouts/Center.module.css

@@ -20,7 +20,7 @@
 
 .box {
   --content-max-width: min(var(--layout-inline-content-max-width),
-                           var(--constrained-content-max-width));
+                           var(--constrained-content-max-width, 100%));
   margin-left: auto;
   margin-right: auto;
   max-width: var(--content-max-width);
@@ -32,7 +32,7 @@
 
 .box-lg {
   --content-max-width: min(var(--layout-inline-lg-content-max-width),
-                           var(--constrained-content-max-width));
+                           var(--constrained-content-max-width, 100%));
 }
 
 .box-xl {

entry_types/scrolled/package/src/frontend/layouts/TwoColumn.module.css

@@ -26,12 +26,12 @@
 
 .inline {
   --content-max-width: min(var(--layout-inline-content-max-width),
-                           var(--constrained-content-max-width));
+                           var(--constrained-content-max-width, 100%));
 }
 
 .inline.width-lg {
   --content-max-width: min(var(--layout-inline-lg-content-max-width),
-                           var(--constrained-content-max-width));
+                           var(--constrained-content-max-width, 100%));
 }
 
 .inline.width-xl {
@@ -123,7 +123,7 @@
 
 .constrainContentWidth .side {
   position: relative;
-  --side-offset: calc((min(var(--layout-inline-content-max-width), var(--constrained-content-max-width)) -
+  --side-offset: calc((min(var(--layout-inline-content-max-width), var(--constrained-content-max-width, 100%)) -
                        var(--content-max-width)) / 2);
   right: var(--side-offset);
 }