Hey i am Sahil Popli describing some useful links for web designing for learning HTML5 & CSS3 and for make some goofy things even without knowing the code.
This website contain four Topics HTML5, CSS3, Code Generators, Responsive Design and some other things
Check HTML5 tags Compatibility at CanIUse.com
CSS3 is the 3rd Draft of Cascading style sheet at W3C
Check CSS3 Compatibility at CanIUse.com , quirksmode, fmbip and Campaign Monitor.
Some online playgrounds for ease Dabblet, CodePen, JsFiddle, CssDeck and 2 online photo editor Live photoshop and pixlr.
Some useful color Generators are Color Picker, Color Density, RGBA Generator, Coloratum, Color Scheme, Color Combos, Color Blender, Gradient For CSS3, Brand Colors and Website Color Grabber.
Genrate texture and Background pattrens at patternify, Noise Texture, Stripe Generator and you can download backgrounds from ava7 and Subtle Patterns .
Some Great CSS3 Codes Generator CSS3 Maker, Ribbon Generator, Css3 Generator, CSS-Text and 10 more .
Sprite Generator with CSS3 and HTML5 Code with Sprite Pad, Sprite Gen.
Shorthand CSS3 and HTMl5 with Zen Coding and Emmet and links for learning Zen Coding and Emmet.
Famous Frameworks to use in your next project Bootstrap, HTML5 Boilerplate Responsive Boilerplate and the final is Ratchet
and some more Genrators Drawter, CSS Menu Maker, CSS3 Generator.IN, Border-Radius.
Responsive web design is a web design approach aimed at crafting sites to provide an optimal viewing experience—easy reading and navigation with a minimum of resizing, panning, and scrolling—across a wide range of devices (from desktop computer monitors to mobile phones) from WIKIPEDIA.
First check your previous projects responsiveness on responsive.is, Responsinator
You can use CSSGRID, 960, CSS Wizardry or you can make your own at Gridpak and Grid Calculator
Some useful Stuff Respond.js, Style Tiles, Masonry, FitText.js and FitVids.js
This section contains all links that not fall in previous categories but important in product development like Wireframing and Balsamiq and you can download Balsamiq on your system.
Tooltip i used in this example
And sample data to fillin your project for text HTML-Ipsum and Ipsum Genrator for images Lorempixel and Placehold.it and you can also use creative commons images at creativecommons.org
You can also download some freebies from WebdesginerDepot and some others and 28 jquery sliders
Convert Your Code to post to webpage at Postable and minify css at CSS Covert and a great tool i found is Convert your Image to CSS at CodePen.io
Before all this read the ABC of web standards at Web Do's and Dont's and 1st Web Designer
Last but not the least i am giving you some Websites to follow to stay update about the web standards.Just bookmark these on your system Web Designer Wall, Web Resources Depot, Spoon Graphics, Web Designe Ledger, 1st Web Designer, Tree House and CSS-Tricks.