Web developers constantly need to be aware of the emergence of new libraries and tools. I found and selected some of the best tools for developing both CSS and JavaScript. This is not just copy-paste - it is a sample based on both recommendations and personal experience.
Frontend development is tricky. And although it is not too difficult to master, it will also not hurt to master some subtleties. Excellent resources appear daily on the net. They can give impetus to your skills and help you better accomplish your task.
Top CSS and Javascript Tools
1) Fileicone')
Collection of 100% -CSS file icons. May be useful for page design.
2) MarxElegant null CSS without any javascript.
3) TransformiconsStunning and well-done animated icons, buttons and symbols made through CSS and SVG.
4) Sanitize.cssProvides sequential rendering of elements, adds the ability to use styles with updates.
5) Loader.cssAmazing set of fast animations on pure CSS
6) SassyFlagsA simple library that adds flags to the site.
7) PrimerCSS framework used in GitHub.
8) FlickityCSS library for creating galleries and sliders without any effort on your part.
9) PushyAdaptive navigation menu. Uses CSS transforms and transits.
10) CSS StatsDisplays statistics about your CSS
11) FlexboxCreate flexbox in 5 minutes using the most common CSS features.
12) FlexbugsSupported and updated by the public list of problems and errors that arise when creating a flexbox.
13) cssPlusA well-working, fast cross-browser layout, based mainly on Flexbox.
14) Flexible.gsAdaptive and easy to use CSS framework for creating grids.
15) RinTemplate library for HTML and SASS based on gulp.
16) WeeAnother easy frontend framework. Helps create complex web page design options.
17) SpaceBaseAnother responsive CSS framework.
18) DecoratorFramework immediately for HTML, JavaScript and CSS.
19) RebarSass / Stylus Mesh Framework
20) LostAnother Stylus-based grid system that works with calc ().
21) RWDGRIDSystem for creating adaptive grids, based on 960grid.
22) ManhattannSimple and clear customizable system for creating meshes on CSS.
23) MaterialHTML5 UI framework using Material Design.
24) LumXOne of the first frontend frameworks, based simultaneously on the specifications of AngularJS and Material Design.
25) MUILightweight framework based on Material Designs.

Any different
26) iconoExcellent set of icons on pure CSS
27) CSS Gradient AnimatorCreates beautiful animated gradients, while you can work with it through a web form.
28) LocalFontHelps to work with fonts in localStorage local storage.
29) Web Font LoadEasy way to install Google Web Fonts on OSX.
30) ai2htmlAn open source script that turns Adobe Illustrator documents into HTML with CSS.

JavaScript libraries and frameworks
31) MarxCSS Reset.
32) SprintA small jQuery-like library with an emphasis on speed and minimal resource consumption (especially for smartphones and tablets)
33) Svidget.jsSVG widget framework
34) Challenger.jsLibrary to add to the page tasks in JavaScript.
35) Verlon.JSPlatform for remote debugging and testing JavaScript. Uses node.js and socket.io.
36) Layzr.JSA small independent library for lazy loading.
37) Clusterize.jsA small plugin for convenient output to the page of large data sets.
38) Elevator.jsA fun plugin to scroll back to the beginning.
39) egg.jsPlugin for adding Easter eggs to pages.
41) epicGridA small library for creating adaptive grids.
42) ramjet.jsA tool for smoothly converting DOM elements to each other.
43) ItemSlide.jsTouch-screen carousel, easy to implement.
44) Plumin.jsCreating and using fonts.
45) smiley.jsThe library rotates all text emoticons by 90 degrees for comfortable viewing.
46) vivus.jsSVG animation library.
47) RimgA set of tools for smoothly creating responsive pages with support for media queries.
48) AnimsitionjQuery plugin for CSS transitions animated pages.
49) Unicoder.jsThe plugin converts text into an unusual form using Unicode characters.
50) Space.jsHTML and JavaScript library for three-dimensional scrolling.
