40%
faster largest contentful paint
380kB
of CSS & JS removed
0
build-step failures since launch
9
days to full rollout
How Meridian Pay's platform team replaced a 400kB component library with CSS Vars Framework and cut their dashboard's load time by 40% in a single quarter.
Client
Meridian Pay
Industry
Financial Services
Timeline
Q1 2026 · 11 weeks
Team size
4 engineers
40%
faster largest contentful paint
380kB
of CSS & JS removed
0
build-step failures since launch
9
days to full rollout
Meridian Pay's internal dashboard had grown around a component library that shipped its own runtime theme engine. Every dark-mode toggle, every density setting, meant recomputing styles in JavaScript on every render. As the dashboard grew past 200 screens, interaction latency crept past 300ms on mid-range laptops.
The team replaced the runtime theme engine with CSS Vars
Framework's :root token
layer. Dark mode became a single data-theme
attribute swap — no JavaScript recalculation, no layout thrash.
"We deleted our theming library entirely. Every color, spacing value, and shadow now lives in one stylesheet, and switching themes is a single attribute change the browser handles natively."
— Dana Whitfield, Staff Engineer, Meridian Pay
Migration happened screen-by-screen behind a feature flag over nine working days, verified against Lighthouse budgets on every merge.
data-theme attribute toggle