HTML & CSS are easy. Grid & Flex I am still learning.
You will find that there is no standard as it seems you can accomplish the samething multiple ways.
Try NoteTab. Much more then just a text editor or in helping in creating webpages. Open and along the bottom click on the HTML-CSS tab then click on from the left side: New HTML5 page so you can see a simplae layout.
Get the Lite version or Pro
https://www.notetab.com/download-now
Go here and use their Tryit editor from examples.
https://www.w3schools.com
Example of a layout. Modify then click on the Run button. Resize the browser window or move the center divider to see changes.
https://www.w3schools.com/css/tryit.asp?filename=tryresponsive_breakpoints
CSS Grid Layout Module
https://www.w3schools.com/css/css_grid.asp
Terminology to start with:
HTML - CSS - Grid - Flex
Stay away from bootstrap. A big headache.
Learn HTML/CSS
http://html.net
HTML Codes, Editors, and Generators
https://www.html.am
Website Creation Process
https://www.quackit.com/create-a-website
A Complete Guide to Grid
https://css-tricks.com/snippets/css/complete-guide-grid
A Complete Guide to Flexbox
https://css-tricks.com/snippets/css/a-guide-to-flexbox
Help sites:
Quackit
https://www.quackit.com
Online HTML Editor
https://www.quackit.com/html/online-html-editor
CSSPortal
https://www.cssportal.com
Post questions:
https://htmlforums.net
CSS Navigation Bar
https://www.w3schools.com/css/css_navbar.asp
CSS Dropdown menu
https://www.w3schools.com/css/css_dropdowns.asp
Creating Fluid Layouts & Images with CSS
https://blog.adobe.com/en/publish/2015/12/07/creating-fluid-layouts-images-with-css.html#gs.zzpxqt
All About Floats
https://css-tricks.com/all-about-floats
Media Queries for Standard Devices
https://css-tricks.com/snippets/css/media-queries-for-standard-devices
Centering in CSS: A Complete Guide
https://css-tricks.com/centering-css-complete-guide
Styling Tables with CSS
https://www.elated.com/styling-tables-with-css
View this example instead. Much simplier. I edit the 2nd link below to do away with most of the col- widths so instead of 12 I have 3 instead.
https://www.w3schools.com/css/tryit.asp?filename=tryresponsive_breakpoints
Nice list
I am replying to bookmark for future reference