diff --git a/web/src/App.tsx b/web/src/App.tsx
index b52261c..58dace1 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -16,6 +16,7 @@ import { BlockTicker } from './components/BlockTicker'
 import { ChainSwitcher } from './components/ChainSwitcher'
 import { Leaderboard } from './components/Leaderboard'
 import { MinerPanel } from './components/MinerPanel'
+import { RuntimePanel } from './components/RuntimePanel'
 import { StatBar } from './components/StatBar'
 import { seconds, windowSpan } from './lib/format'
 import { href, parse, WINDOWS } from './lib/routes'
@@ -67,12 +68,6 @@ export default function App() {
     [chain, navigate],
   )
 
-  /** Back to the standings, keeping the window the panel was opened from. */
-  const closePanel = useCallback(
-    () => navigate(href({ chain, window: route.window })),
-    [chain, route.window, navigate],
-  )
-
   const interval =
     state.summary?.block_interval_seconds ?? state.summary?.target_block_time_seconds ?? 6
   const activeWindow = WINDOWS.find((w) => w.id === route.window) ?? WINDOWS[1]!
@@ -143,7 +138,6 @@ export default function App() {
           block={route.block}
           targetSeconds={info?.target_block_time_seconds ?? 6}
           onResolved={blockResolved}
-          onClose={closePanel}
         />
       )}
 
@@ -163,13 +157,14 @@ export default function App() {
         <MinerPanel chain={chain} miner={route.miner} windowName={route.window} />
       )}
 
-      {/* A miner and an account are pages, not things opened over the board.
-          Each is somebody's own record and the whole subject of the URL that
-          reached it; leaving eleven other miners' rows underneath is the site
-          failing to notice which page it is on. A block keeps the board,
-          because a block is read *against* it — who won this one, and where do
-          they sit — and the ticker below is the row you clicked to get here. */}
-      {!route.account && !route.miner && (
+      {/* Every one of these is a page, not something opened over the board. A
+          URL that names one thing has that thing as its whole subject, and
+          leaving eleven unrelated mining rows underneath is the site failing to
+          notice which page it is on. The board is what `/:chain/:window` is
+          for. */}
+      {route.runtime !== null && chain && <RuntimePanel chain={chain} spec={route.runtime} />}
+
+      {!route.account && !route.miner && !route.block && route.runtime === null && (
         <div className="two-col">
           <section className="panel">
             <div className="panel-head">
@@ -215,6 +210,22 @@ export default function App() {
           is the only identity the chain itself asserts. An <code>elsewhere</code> tag means the
           name was earned by the same reward preimage on another chain, not observed on this one.
         </span>
+        {state.summary?.spec_version !== null && state.summary?.spec_version !== undefined && (
+          <span>
+            {/* "Decoded how?" has an answer, and it is a page. Every event and
+                reward on this site was read against this runtime's own type
+                registry rather than against anything written here, so the
+                runtime is a load-bearing part of the explanation and not a
+                footnote. */}
+            Rewards and transfers are decoded against the chain's own metadata — the type registry
+            the node produces by running the runtime WASM in each block's state, not a schema
+            written here. This chain is on{' '}
+            <Link to={href({ chain, runtime: state.summary.spec_version })}>
+              {state.summary.spec_name ?? 'runtime'} v{state.summary.spec_version}
+            </Link>
+            .
+          </span>
+        )}
         <span className="colophon">
           {/* Its own line rather than a fourth item in the `space-between`
               flow: the three above are caveats about the numbers, this is
diff --git a/web/src/components/BlockPanel.tsx b/web/src/components/BlockPanel.tsx
index 8a8c556..ad7f8da 100644
--- a/web/src/components/BlockPanel.tsx
+++ b/web/src/components/BlockPanel.tsx
@@ -56,7 +56,6 @@ export function BlockPanel({
   block,
   targetSeconds,
   onResolved,
-  onClose,
 }: {
   chain: string
   /** Height or hash, as it appeared in the URL. */
@@ -65,7 +64,6 @@ export function BlockPanel({
   targetSeconds: number
   /** Called with the canonical hash once a height has resolved to one. */
   onResolved: (hash: string) => void
-  onClose: () => void
 }) {
   const [detail, setDetail] = useState<BlockDetail | null>(null)
   const [error, setError] = useState<string | null>(null)
@@ -122,21 +120,9 @@ export function BlockPanel({
             {detail?.hash ?? ''}
           </div>
         </div>
-        <button
-          className="segmented"
-          style={{
-            padding: '7px 13px',
-            font: 'inherit',
-            fontSize: 12,
-            letterSpacing: '0.1em',
-            textTransform: 'uppercase',
-            color: 'var(--text-secondary)',
-            cursor: 'pointer',
-          }}
-          onClick={onClose}
-        >
-          Close
-        </button>
+        {/* No close button: this is a URL somebody navigated to, not a dialog
+            that opened over something they were reading. The back button and
+            the chain chip both already do what it would. */}
       </div>
 
       {error && <p className="empty">{error}</p>}