Update anchor-position-1.vim

https://www.w3.org/TR/2024/WD-css-anchor-position-1-20240326/

after/syntax/css/anchor-position-1.vim

@@ -1,3 +1,4 @@
 syn keyword cssFontProp contained anchor-name anchor-scope inset-area position-anchor position-try position-try-options position-try-order
-syn keyword cssFontAttr contained span-left span-right span-x-start span-x-end x-self-start x-self-end span-x-self-start span-x-self-end span-all span-top span-bottom span-y-start span-y-end y-self-start y-self-end span-y-self-start span-y-self-end block-start block-end span-block-start span-block-end self-block-start self-block-end span-self-block-start span-self-block-end inline-start inline-end span-inline-start span-inline-end self-inline-start self-inline-end span-self-inline-start span-self-inline-end span-start span-end self-start self-end span-self-start span-self-end implicit most-width most-height most-block-size most-inline-size flip-block flip-inline flip-start
+syn keyword cssFontAttr contained span-left span-right span-x-start span-x-end x-self-start x-self-end span-x-self-start span-x-self-end span-all span-top span-bottom span-y-start span-y-end y-self-start y-self-end span-y-self-start span-y-self-end block-start block-end span-block-start span-block-end self-block-start self-block-end span-self-block-start span-self-block-end inline-start inline-end span-inline-start span-inline-end self-inline-start self-inline-end span-self-inline-start span-self-inline-end span-start span-end self-start self-end span-self-start span-self-end implicit anchor-center most-width most-height most-block-size most-inline-size flip-block flip-inline flip-start
+syn region cssFunction contained matchgroup=cssFunctionName start="\<anchor\(-size\)\=\s*(" end=")" oneline keepend
 syn match cssFontDescriptor "@position-try\>" nextgroup=cssFontDescriptorBlock skipwhite skipnl

test/test.css

@@ -52,13 +52,16 @@
 	display: span-self-start;
 	display: span-self-end;
 	display: implicit;
+	display: anchor-center;
 	display: most-width;
 	display: most-height;
 	display: most-block-size;
 	display: most-inline-size;
 	display: flip-block;
 	display: flip-inline;
-	display: flip-start
+	display: flip-start;
+	display: anchor(--x 50%);
+	display: anchor-size(--foo height);
 }
 
 .animations-1 {