Quick Responsive Webpage Fix

I have an existing HTML / CSS / JavaScript page whose desktop layout is fine, but it falls apart on smartphones and tablets. Margins slip, elements overlap, and one button refuses to respond on both desktop and mobile browsers. I need the page tightened up without touching the overall look and feel.

What I need you to do
• Tidy the mobile and tablet breakpoints so the layout matches the current desktop design
• Correct spacing and alignment wherever they drift
• Restore the malfunctioning button’s original behaviour (it should simply work the way it already does on desktop once the issue is fixed)
• Run quick checks in Chrome, Firefox, Safari and the main mobile browsers to confirm everything is clean and that no new console errors appear

Deliverables
• Updated source files (HTML, CSS, JS)
• A fully responsive page with no layout glitches on smartphones or tablets
• A short changelog explaining what you adjusted and where
• Zero new console errors in any tested browser

Please add your estimated turnaround time and link to one live example of a similar fix you have done. I expect this to be a small, quick job for an experienced frontend developer and will review bids as they arrive so we can get started right away.