Kilian Valkhof

Front-end & user experience developer, Jedi.

How I built my own browser

CSS & HTML, Design, 10 February 2020

Building your own browser sounds like a terrible idea, especially if you’re a front-end developer by trade and don’t know any C++ or other native language. Even so a couple of years ago I decided to see if I could and by now my browser has developed into a serious project.

Design tokens 101

Design, 7 February 2020

Yesterday, I gave a ⚡ lightning talk on design tokens at the @ReactAmsterdam meetup. I’ve been to a few React Amsterdam meetups and there’s always a really good vibe so I was really happy I got to do a lightning talk on a subject I care about. There were about 200 people in the room and it was again a really nice crowd.

Using easing for more than just CSS transitions

CSS & HTML, 6 January 2020

We can define easing curves for the transitions and animations on our websites to give them a more natural and subtle feel. But it’s not just animations that benefit from easing curves. Any time there is a transition between two states an easing curve will make that feel more natural and less harsh.

Make Your Electron App Feel at Home Everywhere

Electron, 16 December 2019

I got invited to talk about Electron at QCon San Francisco in November and the video and transcript of the presentation are now available. Electron gives you the power to write a single application for Windows, MacOS and Linux. But Electron apps can easily feel out of place among other applications, exactly because you have so much freedom in designing your UI.

The box model is not layout

Design, 8 October 2019

One term that keeps coming up in the design community as a stand-in for layout is “box model”, for example in “Why don’t design tools have the box model?” The CSS Box model is a well-defined term though, and it does not do layout.

If we keep referring to our imaginary perfect layout system in design tools as “box model”, we risk getting the wrong thing.

Polypane browser for responsive web development and design Hi, I'm Kilian. I make Polypane, the browser for responsive web development and design. If you're reading this site, that's probably interesting to you. Try it out!

I develop more software and tools:


Use the design system you already have


A cross-platform, simple and smart autosaving scratchpad.

A Messenger Adventure!

Go on a text adventure in Facebook Messenger.


The latest Electron news, articles, apps and interviews.


Drag-and-drop lossless compression of PNG and JPG images for web.

Messenger Demo Viewer

Demo your (bot) interactions on Messenger.