Improve accessibility and polish page styling

app/polish.css

@@ -1,4 +1,21 @@
 /* Responsive corrections shared by both languages. */
+.skip-link {
+  position: fixed;
+  inset-block-start: 12px;
+  inset-inline-start: 12px;
+  z-index: 1000;
+  padding: 10px 14px;
+  transform: translateY(calc(-100% - 16px));
+  border: 1px solid var(--line);
+  border-radius: var(--radius-control);
+  color: var(--text);
+  background: var(--panel);
+  box-shadow: 0 4px 14px #03060a55;
+  white-space: nowrap;
+}
+.skip-link:focus-visible {
+  transform: translateY(0);
+}
 .language-switcher {
   display: inline-flex;
   align-items: center;
@@ -107,6 +124,22 @@ html[lang="ru"] .mode-row h3 span {
   display: flex;
   flex-direction: column;
 }
+.desktop-download-card {
+  margin-bottom: 40px;
+}
+.desktop-download-version {
+  margin-top: 16px;
+}
+.download-build-link {
+  margin-inline-end: 8px;
+  margin-block-end: 8px;
+}
+.tool-card-note {
+  font-size: 11px;
+}
+.tool-card-note-spaced {
+  margin-top: 20px;
+}
 .tool-card pre,
 .token-box code {
   max-width: 100%;