Son Blue is the blue member of a matched theme family, and it now comes in two appearances: Firefox picks the light or the dark one to match your system setting, and switches with it. In the light appearance a pale sky-blue tab strip sits under a near-white toolbar; in the dark one the same layout is built on deep navy surfaces. In both, the active tab is a solid blue pill with white text — so the tab you are on is unmistakable at a glance, even across a crowded tab bar. The address bar is a clean field with a soft blue hairline, and the same blue marks focus, selection, and attention states. Inactive tab labels are kept genuinely readable rather than faded out. Every text and icon pairing was checked against WCAG contrast targets. There are no background images, no gradients, and no neon. Pairs with Son Light and Son Dark.
