The current BigCommerce storefront shows layout distortions on every screen size—mobile, tablet, and even large desktop monitors. Menus overlap hero images, product grids wrap unpredictably, and some banners disappear below the fold. The underlying content and theme files are intact; the problem lies purely in the responsive breakpoints, CSS overrides, and possibly a few theme-level handlebars that now output extra wrappers. Scope of work – Audit the theme’s CSS/SCSS, Stencil templates, and any custom JavaScript that touches layout. – Correct or refine breakpoints so the site scales cleanly from 320 px wide phones through full-width desktop. – Ensure flex/grid alignment of product cards, navigation, banner sliders, and the checkout header on all modern browsers. – Leave page speed unaffected (or improved) by avoiding heavy libraries. Acceptance criteria 1. No horizontal scrolling at common widths (320 px, 375 px, 768 px, 1024 px, 1366 px). 2. Navigation, cart icon, and search bar remain visible and tappable without overlap. 3. Product grid holds consistent three-column tablet view and four-column desktop view without gaps. 4. Google Mobile-Friendly Test returns a pass on key URLs. 5. All edits delivered via a Git commit or clearly documented file list so future theme updates remain conflict-free. Access provided: Stencil theme files in a private Git repo and store-level admin credentials for preview. Feel free to suggest minor UI tweaks if they simplify the responsive fix, but the visual style must stay on-brand. Turnaround: an initial audit within 24 hours and full fixes ready for review in three business days.