What changed, and why
- Header: 13 top-level dropdowns wrapping onto two rows (the reason the live CSS has three separate media queries just to shrink the nav font) are collapsed into 5 grouped mega-menus. One row, at every width.
- Header: darker, higher-contrast bar with a sticky position so it stays available while scrolling long calculator pages.
- Footer: the ~17-column link wall is grouped into the same categories as the header, with a "+N more" disclosure per column so deep links still exist for search engines without dominating the page visually.
- Ad placement: professional B2B ads run in sticky rails to the left/right of the content on wide screens โ never inside the reading column. Below the width where rails would squeeze the content, a single inline unit is used instead, since there's no gutter to put a rail in.
Ad โ inline unit (mobile/narrow only)
Jet Fuel Head Calculator
Placeholder calculator card to show link/button styling under the new header.
Compression Spring Calculator
Placeholder calculator card.
O-Ring Size Finder
Placeholder calculator card.