When comparing Spectre vs Cirrus, the Slant community recommends Spectre for most people. In the question“What is the best CSS framework?” Spectre is ranked 11th while Cirrus is ranked 23rd.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lightweight
Pro Clean
Very clean design compared to bootstrap.
Pro Responsive
Works well on any device.
Pro Mobile ready
Spectre can be used to create mobile websites easily. With all the regular built in elements (buttons, menus, grids etc).
Pro Simple
Contains only the basics, no extra fluff.
Pro Open source
Spectre is used through Github, and is open source.

Pro Supports Flexbox and CSS Grid
Supports both Flexbox and CSS grid making it a great modern choice for designing web apps.

Pro CSS Only
No additional JS/jQuery required to use.

Pro Mobile Responsive
Extremely responsive and supports many smaller screens.

Pro Open Source
Open source and quite actively maintained on Github.

Pro Lightweight
Much smaller than Bootstrap with just as much flexibility.
Cons
Con Not actively developed
