When comparing GroundworkCSS vs Flutter, the Slant community recommends GroundworkCSS for most people. In the question“What is the best CSS framework?” GroundworkCSS is ranked 16th while Flutter is ranked 25th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Responsive text
Pro GroundworkCSS uses Autoprefixer
Autoprefixer is a postprocessor that allows writing code without vendor prefixes.
Pro Sass and CoffeeScript components
Pro Accessibility focused
Pro Semantic
Pro Grid system
Pro Open source
Pro Great developer tools debug/hotreload/analyser
Pro Based on Dart language
Dart is a Java like language, easy to learn and startup fast for millions of Java developers.
Pro A single codebase for iOS AND Android
Pro Fast
The developer's goal is to allow people to make apps running at 120 FPS.
Cons
Con Still in development
According to the website, Flutter is still in its early stages of development.
Con Based on Dart language
Dart is a Java like language, easy to learn and startup fast for millions of Java developers. BUT if you have to learn it ... it's a con.
Con Dart is unpopular and never gained serious community traction like Kotlin or Java
Con Does not support 32-bit iOS devices
If you plan on targeting iPhone 5, 5C or earlier, you can forget about Flutter.