fix: mobile UX across all 19 themes

Audit found universal mobile issues in every theme + shared CSS:

- body/overlay height:100vh had no 100dvh dynamic-viewport fallback on any theme
- @media(max-width:640px) was too minimal; 3 themes had no .content/.modal-inner reduction
- .modal-close buttons had zero padding → tap target well below 44×44px
- .transmit-btn and .page-nav a vertical height too small on most themes

Fixes applied:

Go/CSS common (shared.css):
- Add .modal-close padding + min 44×44px touch target
- Add overflow:hidden to #sno-wild-banner to prevent wild-mode banner overflow
- Add mobile @media override block with !important for .modal-inner padding,
  .transmit-btn, and .page-nav a min-height to guarantee 44px touch targets

All 19 themes:
- Add height:100dvh fallback after height:100vh on body and .overlay
- Expand @media(max-width:640px) with missing .content/.modal-inner padding,
  .transmit-btn min-height, and .modal-close touch-target padding where absent

Specific themes:
- DOS: enlarge .transmit-btn base padding from 4px to 8px
- Spaceage: bump .post-text from 0.86rem (~13.8px) to 0.9rem (~14.4px)
- Brutalist / Retrofuture / Synthwave: these previously had no .content or
  .modal-inner reduction in their media queries; now filled in

0 files changed, 0 insertions, 0 deletions