CSP for Cotiless: From Inline Chaos to Strict Control

Cotiless had the kind of frontend stack I see all the time: marketing scripts, analytics, consent tooling, a couple of “just paste this snippet” integrations, and a team that wanted security without breaking the site. That’s exactly where CSP gets messy. The goal wasn’t to build the most academic Content Security Policy. The goal was to ship a policy that reduced XSS risk, survived real production traffic, and didn’t turn every release into a blame game between security and frontend. ...

May 19, 2026 · 6 min · headertest.com

CSP for MathJax: Common Mistakes and Fixes

MathJax is one of those libraries that looks harmless until you lock down your CSP and everything explodes. You ship a clean policy, reload the page, and suddenly your equations stay as raw TeX, inline styles get blocked, fonts don’t load, and the console turns into a crime scene. I’ve seen teams blame MathJax, blame CSP, then quietly add 'unsafe-inline' everywhere just to make the pain stop. That works, but it’s a bad trade. ...

May 18, 2026 · 6 min · headertest.com

CSP for MapLibre GL JS: A Real-World Before and After

I’ve seen this pattern a lot: a team adds MapLibre GL JS to an otherwise locked-down site, ships to staging, and the map quietly explodes under Content Security Policy. No tiles. No markers. Maybe the page itself works, but the console fills up with CSP errors about workers, styles, images, and network requests. Then somebody reaches for 'unsafe-inline' or loosens connect-src to https: and calls it a day. That’s how good CSPs die. ...

May 16, 2026 · 7 min · headertest.com

CSP for StackBlitz Embeds: A Before-and-After Fix

I’ve seen this exact failure more than once: a docs page ships with a pretty strict Content Security Policy, someone drops in a StackBlitz embed for an interactive demo, and suddenly the page shows a blank box or a browser console full of CSP errors. The frustrating part is that nothing feels obviously broken. The iframe markup looks fine. The StackBlitz project URL loads directly in a new tab. But embedded inside your site? Dead. ...

May 15, 2026 · 6 min · headertest.com

CSP for Fabric UI: What Works, What Breaks

If you’ve ever tried to lock down a frontend with Content Security Policy and then dropped in Fabric UI, you already know the pattern: the CSP gets stricter, the UI gets weird, and somebody says “just add unsafe-inline” like that doesn’t defeat half the point. Fabric UI sits in an awkward spot for CSP. Some parts play nicely enough. Other parts push you toward looser policies, especially around styles. If your goal is a hardened CSP without turning your app into a pile of exceptions, you need to know where Fabric UI helps and where it fights you. ...

May 13, 2026 · 7 min · headertest.com

CSP for NeoMagic.css: Lock It Down Without Breaking Styles

NeoMagic.css is the kind of CSS framework people pick because they want speed, tiny bundles, and fewer moving parts. Good call. But once you start shipping a real app with analytics, fonts, icons, and maybe a little JavaScript sugar, your CSP usually turns into a weird mix of good intentions and emergency exceptions. I’ve seen this a lot: the app starts with a nice strict policy, then somebody adds a tag manager, then a consent banner, then inline styles sneak in, and now style-src 'unsafe-inline' is hanging around forever like a bad temporary fix. ...

May 11, 2026 · 7 min · headertest.com

CSP for Phosphor Icons: CDN, SVG, React, and Webfont

Phosphor Icons are easy to love: clean set, multiple weights, works fine in React, and the SVG output is usually painless. The annoying part starts when you lock down Content Security Policy and realize your icon strategy has security consequences. I’ve run into this a lot. Teams pick an icon package early, then add CSP later, and suddenly a harmless-looking icon library turns into a debate about style-src, font-src, inline SVG, third-party CDNs, and whether someone really needs a runtime script to paint a caret. ...

May 10, 2026 · 6 min · headertest.com

CSP for Loom Embeds: Common Mistakes and Fixes

Loom embeds look simple: paste an iframe, ship it, move on. Then CSP blocks it, the video area goes blank, and somebody “fixes” it by slapping https: into frame-src or loosening half the policy. I’ve seen this happen more than once. Loom is exactly the kind of third-party embed that exposes weak CSP habits: developers guess at directives, over-allow sources, or forget that an iframe usually pulls in more than one origin. ...

May 9, 2026 · 6 min · headertest.com

CSP for Stripe Pricing Table: A Real-World Fix

I’ve seen this exact failure more than once: marketing drops in a Stripe pricing table, everything looks fine locally, then production CSP quietly blocks it and the page ships half-broken. The annoying part is that Stripe’s pricing table is simple to embed, but CSP rarely is. If your site already has Google Tag Manager, analytics, consent tooling, and a reasonably locked-down policy, adding one more third-party script can turn into a guessing game fast. ...

May 8, 2026 · 6 min · headertest.com

CSP for Typekit: A Practical Setup Guide

Adobe Typekit — now usually called Adobe Fonts — is one of those services that looks simple until CSP enters the room. You paste the embed code, the fonts load, everyone is happy. Then you lock down your site with Content Security Policy and suddenly your typography falls back to Arial. I’ve had this break in production more than once. The annoying part is that Typekit needs more than one CSP directive, and the exact domains matter. If you only allow scripts, the stylesheet gets blocked. If you allow styles but forget fonts, the CSS loads and the fonts still fail. Classic. ...

May 5, 2026 · 6 min · headertest.com