Every frontend developer has been there. You're in the middle of building a component, and you need a box shadow that looks just right . So you write box-shadow: 5px 5px 10px rgba(0,0,0,0.3) and it looks wrong. You tweak the numbers. Still wrong. You open a random generator site, it's covered in ads, asks you to sign up, and crashes on mobile. That frustration is why I built CSS Toolkit — a free collection of 8 CSS tools that run entirely in your browser with no login, no ads, and no nonsense. Here's what's in it and why each tool exists. 1. PX to REM Converter The most common task no one wants to do manually. If your root font size is 16px, then 24px becomes 1.5rem . Simple enough. But what about when you're migrating a legacy stylesheet with 200 pixel values? Doing that math one by one is a waste of time. The PX to REM converter supports bulk input — paste a list of pixel values, set your base font size, and get all rem equivalents at once. 2. PX to EM Converter Em works differently from rem.…