This is a no-brainer guide to installation of Solidity computer language that allows you to write something called "smart contract". And Remix IDE is a really handy development tool to assist the development of solidity smart contract programs. Skipping to the conclusion, we can use a code as follows suggested in this Wordpress trac issue.
Install Solidity using brew
Easy. There need only 2 lines in your terminal.
brew tap ethereum/ethereum brew install solidity
Then you have the environment to get started with the smart contract programming.
Install Remix IDE
You are now going to use node.js. Install node's web server globally if you have not yet.
npm install -g http-server
Then install remix ide.
npm install remix-ide -g
Run the remix ide.
Open the web browser and access to http://localhost:8080. You might have a conflict of the port which prevents the remix IDE from launching. You will need to change either node web server or that of another service using the port.
Thank you for reading!