Simon Willison’s Weblog

viewport-preview (via) I built a tiny tool which lets you preview a URL in a bunch of different common browser viewport widths, using iframes.

Posted 26th July 2022 at 12 am

Recent articles

Hacking the WiFi-enabled color screen GitHub Universe conference badge - 28th October 2025
Video: Building a tool to copy-paste share terminal sessions using Claude Code for web - 23rd October 2025
Dane Stuckey (OpenAI CISO) on prompt injection risks for ChatGPT Atlas - 22nd October 2025

css 229 iframes 21 mobile 40 projects 500 testing 64

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