[css-scroll-snap] Use <length-percentage>, fix linking errors.

Author: tabatkins

css-scroll-snap-1/Overview.bs

@@ -28,6 +28,9 @@ Status Text:
 
 <pre class=link-defaults>
 spec: selectors-4; type: selector; text: :target
+spec: css-pseudo-4; type: selector;
+    text: ::first-line
+    text: ::first-letter
 </pre>
 
 Introduction {#intro}
@@ -400,7 +403,7 @@ Scroll Snapport: the 'scroll-padding' property {#scroll-padding}
 
     <pre class="propdef">
     Name: scroll-padding
-    Value: [ <<length>> | <<percentage>> ]{1,4}
+    Value: <<length-percentage>>{1,4}
     Initial: 0
     Applies to: <a>scroll containers</a>
     Inherited: no
@@ -945,7 +948,7 @@ Physical Longhands for 'scroll-padding' {#padding-longhands-physical}
 
     <pre class="propdef">
     Name: scroll-padding-top, scroll-padding-right, scroll-padding-bottom, scroll-padding-left
-    Value: <<length>> | <<percentage>>
+    Value: <<length-percentage>>
     Initial: 0
     Applies to: <a>scroll containers</a>
     Inherited: no
@@ -964,7 +967,7 @@ Flow-relative Longhands for 'scroll-padding'  {#padding-longhands-logical}
 
     <pre class="propdef">
     Name: scroll-padding-inline-start, scroll-padding-block-start, scroll-padding-inline-end, scroll-padding-block-end
-    Value: <<length>> | <<percentage>>
+    Value: <<length-percentage>>
     Initial: 0
     Applies to: <a>scroll containers</a>
     Inherited: no
@@ -980,7 +983,7 @@ Flow-relative Longhands for 'scroll-padding'  {#padding-longhands-logical}
 
     <pre class="propdef">
     Name: scroll-padding-block, scroll-padding-inline
-    Value: [ <<length>> | <<percentage>> ]{1,2}
+    Value: <<length-percentage>>{1,2}
     Initial: 0
     Applies to: all elements
     Inherited: no