Migration from Bootstrap3.3.7 to Bootstrap 5.3.8

[MuhammadAashirAslam]

• Upgraded Bootstrap from 3.3.7 to 5.3.8 CDN bundle (CSS & JS) in head layouts and removed obsolete IE8/9 compatibility layers.
• Simplified HTML layouts by deleting nested row/column wrappers ("div-soup") around section headers, paragraph tags, and obsolete caret helper elements.
• Replaced custom CSS classes with modern native Bootstrap 5 grid, flexbox, and alignment utilities (e.g., col-flex -> d-flex flex-column, vertical-align -> d-flex align-items-center, no-margin -> m-0).
• Consolidated main styles by deleting modern-business.css and merging rules into customstyles.css.
• Purged duplicate CSS rules, legacy browser vendor prefixes, and obsolete panel/card dual-class selectors from stylesheets.
• Compensated for spacing changes by shifting the 20px bottom-margin from the removed headers globally to the .section-header class.
• Realigned page footer components, custom workshops, and team grids using standard Bootstrap 5 container, rounding, and spacing parameters.

Documentation:

• BS5 Migration: https://getbootstrap.com/docs/5.3/migration/
• Grid System: https://getbootstrap.com/docs/5.3/layout/grid/
• Cards (replacing Panels): https://getbootstrap.com/docs/5.3/components/card/
• Spacing: https://getbootstrap.com/docs/5.3/utilities/spacing/
• Flexbox: https://getbootstrap.com/docs/5.3/utilities/flex/
• Dropdowns: https://getbootstrap.com/docs/5.3/components/dropdowns/