Top 20 NuGet CSS Packages

Created and designed by Google, Material Design is a design language that combines the classic principles of successful design along with innovation and technology. Google's goal is to develop a system of design that allows for a unified user experience across all their products on any platform.
Material Design Lite (MDL) lets you add a Material Design look and feel to your static content websites. It doesn't rely on any JavaScript frameworks or libraries. Optimized for cross-device use, gracefully degrades in older browsers, and offers an experience that is accessible from the get-go.
Some web useful extension methods for .NET 4.0 or above
Right to left and left to right Bootstrap Less Source
Angular Bootstrap TimePicker directive
Enables you to work with animate.css class more easily and conveniently.
Lesshint is a tool to aid you in writing clean and consistent Less.
Font Awesome Bootstrap Checkboxes and Radios. Pure css way to make inputs look prettier for mvc
Effortlessly create, manage and style text in Xamarin.Android and Xamarin.iOS using HTML and CSS style sheets
A simple set of best practices to get HTML5 projects off on the right foot.
FSharp DSL for CSS
Effortlessly create, manage and style text in Android and iOS using HTML and CSS style sheets
Library for working with Color on iOS and Android
The core implementation library for Frappe. Frappe is a compile time bundler for JavaScript, Css, and Less for high volume, high performance ASP.NET sites.
AngleSharp is the ultimate angle brackets parser library. It parses HTML5, CSS3, and XML to construct a DOM based on the official W3C specification.
A subset of CSS's flexbox layout algorithm and box model.
LibSass .Net wrapper that implements Sass compilation to CSS.
The goal of a reset stylesheet is to reduce browser inconsistencies in things like default line heights, margins and font sizes of headings, and so on.
Extension for NancyFx