fix: reduce padding and spacing for mobile

Main: px-4 py-6 on mobile (was px-8 py-12). Section accordion:
mb/py on inactive links tightened to 1/1 on mobile, space-y-0
between sections. Active title text-xl on mobile to prevent
wrapping at ~400px, matches inactive title size.

src/widgets/SectionsAccordion/ui/SectionsAccordion/SectionsAccordion.tsx

@@ -28,7 +28,7 @@ export function SectionsAccordion({ sections, activeSlug, children }: Props) {
   const slots = Children.toArray(children);
 
   return (
-    <div className="space-y-2">
+    <div className="space-y-0 sm:space-y-2">
       {sections.map((section, i) => (
         <SectionAccordion
           key={section.slug}