docs: fix API docs sidebar overscroll from topbar offset (#49)

Scalar's --scalar-y-offset shifts the sidebar's top position below
the WarpTopbar, but doesn't reduce the sidebar's total height. This
caused the sidebar to extend past the viewport bottom by exactly
the topbar height (3.5rem mobile / 4rem desktop), producing a
slight overscroll at the top and bottom of the main scroll area.

Fix: add max-height: calc(100vh - var(--warp-topbar-height)) to the
.sidebar class in the Scalar customCss block.

Co-authored-by: Oz <oz-agent@warp.dev>

Author: rachaelrenk

src/pages/api.astro

@@ -292,6 +292,14 @@ const specJson = JSON.stringify(specObject);
             --scalar-sidebar-item-active-background: #fafafa;
             --scalar-sidebar-item-hover-background: #fafafa;
           }
+          /* Fix sidebar height: Scalar's --scalar-y-offset shifts the
+             sidebar's top position below the topbar, but doesn't reduce
+             the sidebar's total height. Without this, the sidebar extends
+             past the viewport bottom by the topbar height, causing a
+             slight overscroll at the top and bottom. */
+          .sidebar {
+            max-height: calc(100vh - var(--warp-topbar-height)) !important;
+          }
           /* Hide Developer Tools toolbar */
           .references-developer-tools,
           .api-reference-toolbar { display: none !important; }