Add borders-4.vim

https://www.w3.org/TR/2025/WD-css-borders-4-20250722/#border-radius

This commit also moves some keywords from backgrounds-4 to brders-4.

after/syntax/css/backgrounds-4.vim

@@ -1,2 +1,2 @@
-syn keyword cssFontProp contained background-position-x background-position-y background-position-inline background-position-block corners corner-shape border-limit border-clip border-clip-top border-clip-right border-clip-bottom border-clip-left
-syn keyword cssFontAttr contained x-start x-end y-start y-end bevel scoop notch
+syn keyword cssFontProp contained background-position-x background-position-y background-position-inline background-position-block
+syn keyword cssFontAttr contained x-start x-end y-start y-end

after/syntax/css/borders-4.vim

@@ -0,0 +1,3 @@
+syn keyword cssFontProp contained border-top-radius border-right-radius border-bottom-radius border-left-radius border-block-start-radius border-block-end-radius border-inline-start-radius border-inline-end-radius corner-top-left-shape corner-top-right-shape corner-bottom-right-shape corner-bottom-left-shape corner-start-start-shape corner-start-end-shape corner-end-start-shape corner-end-end-shape corner-top-shape corner-right-shape corner-bottom-shape corner-left-shape corner-block-start-shape corner-block-end-shape corner-inline-start-shape corner-inline-end-shape corner-shape corners border-limit border-clip border-clip-top border-clip-right border-clip-bottom border-clip-left box-shadow-color box-shadow-offset box-shadow-blur box-shadow-spread box-shadow-position border-shape
+syn keyword cssFontAttr contained squircle bevel scoop notch sides corners
+syn region cssFunction contained matchgroup=cssFunctionName start="\<superellipse\s*(" end=")" oneline keepend

after/syntax/css/webvtt1.vim

@@ -1,2 +1,2 @@
-syn match cssPseudoClassId contained "::\<cue\(-region\)\=\>"
+syn keyword cssPseudoClassId contained cue cue-region
 syn region cssPseudoClassLang matchgroup=cssPseudoClassId start="::cue\(-region\)\=(" end=")" oneline

test/test.css

@@ -84,6 +84,37 @@
   background-position-y: auto;
   background-position-inline: auto;
   background-position-block: auto;
+  display: x-start;
+  display: x-end;
+  display: y-start;
+  display: y-end;
+}
+
+.borders-4 {
+	border-top-radius: auto;
+	border-right-radius: auto;
+	border-bottom-radius: auto;
+	border-left-radius: auto;
+	border-block-start-radius: auto;
+	border-block-end-radius: auto;
+	border-inline-start-radius: auto;
+	border-inline-end-radius: auto;
+	corner-top-left-shape: auto;
+	corner-top-right-shape: auto;
+	corner-bottom-right-shape: auto;
+	corner-bottom-left-shape: auto;
+	corner-start-start-shape: auto;
+	corner-start-end-shape: auto;
+	corner-end-start-shape: auto;
+	corner-end-end-shape: auto;
+	corner-top-shape: auto;
+	corner-right-shape: auto;
+	corner-bottom-shape: auto;
+	corner-left-shape: auto;
+	corner-inline-start-shape: auto;
+	corner-inline-end-shape: auto;
+	corner-block-start-shape: auto;
+	corner-block-end-shape: auto;
   corner-shape: auto;
   corners: auto;
   border-limit: auto;
@@ -92,13 +123,19 @@
   border-clip-right: auto;
   border-clip-bottom: auto;
   border-clip-left: auto;
-  display: x-start;
-  display: x-end;
-  display: y-start;
-  display: y-end;
+	box-shadow-color: auto;
+	box-shadow-offset: auto;
+	box-shadow-blur: auto;
+	box-shadow-spread: auto;
+	box-shadow-position: auto;
+	border-shape: auto;
+	display: squircle;
   display: bevel;
   display: scoop;
   display: notch;
+	display: superellipse(1);
+	display: sides;
+	display: corners;
 }
 
 .box-3 {