Fix link errors

Author: Jihye Hong

css-nav-1/Overview.bs

@@ -35,10 +35,10 @@ spec: html; urlPrefix: https://html.spec.whatwg.org/multipage/;
 spec: dom; urlPrefix: https://dom.spec.whatwg.org/
     type: dfn;
         text: document element
-spec: feature-policy; urlPrefix: https://wicg.github.io/feature-policy/
+spec: feature-policy; urlPrefix: https://w3c.github.io/webappsec-feature-policy/
     type: dfn;
         text: is enabled; url: is-feature-enabled
-spec: overscroll-behavior; urlPrefix: https://wicg.github.io/overscroll-behavior/;
+spec: overscroll-behavior; urlPrefix: https://drafts.csswg.org/css-overscroll-behavior-1/;
     type: dfn;
         text: scroll boundary
 spec: css2; urlPrefix: https://drafts.csswg.org/css2/
@@ -497,7 +497,7 @@ Note: the {{focusableAreas()}} and {{getSpatialNavigationContainer()}} methods a
 <div class=example id=focusAreas-visible>
     The following code shows how to get all the visible focusable elements in the current page using {{Element/focusableAreas()}}.
     If the method finds a <a>spatial navigation container</a>, it recursively finds focusable areas inside it.
-	However, <code>'visible'</code> is given to the {{FocusableAreasOptions/mode}} attribute of this method, 
+	However, <code>visible</code> is given to the {{FocusableAreasOptions/mode}} attribute of this method, 
     the focusable element which isn’t inside the <a>scrollport</a> is excluded from the result.
 
     <pre><code highlight=markup>
@@ -1054,7 +1054,7 @@ run the following steps:
 2. The User Agent should <a spec=infra for=set>remove</a> from <var>focusables</var> items that have a [=DOM anchor=] whose <a element-attr spec=html><code>tabindex</code></a> attribute is set to a negative value.
 
     Note: This is a "SHOULD" in order to mirror the exclusion of elements with negative tabindex
-    from the <a>sequential focus navigation order</a> as defined in [[HTML#the-tabindex-attribute]].
+    from the <a>sequential focus navigation order</a> as defined in [[HTML#attr-tabindex]].
 3. If <var>visibleOnly</var> is <code>false</code>,
     return <var>focusables</var>.
 
@@ -1078,7 +1078,7 @@ run the following steps:
     authors should use make these elements unreachable to spatial navigation
     using the same best practices as for making elements unreachable to sequential navigation,
     such as using <code>tab-index="-1"</code>
-    or the <a href="https://github.com/WICG/inert"><code>inert</code></a> attribute.
+    or the <a href="https://html.spec.whatwg.org/multipage/interaction.html#inert"><code>inert</code></a> attribute.
     </div>
 
 6. Return <var>visibles</var>.