redesigned warning alert

[ShreshthaKriti]

FIN-21: #21

[benjaminaaron]

I get Module not found: Can't resolve '@material-ui/lab/Alert'. Did you forget to commit your changes in package.json?

[benjaminaaron]

Looks nice, cool choice with the Alert package 👍

Can you make the content of the alert box centered? This is how it looks for me and there is empty space on the right side:

Also, as written on the Trello card, it would be great if the box is not in the TopBar but below it. That requires moving it out of TopBar.jsx and somewhere else where it can always be displayed not matter on which subsite the user is. Probably the right place is in App.jsx below <TopBar /> 🤔

[benjaminaaron]

🔹 The addition to package.json is still missing
🔹 Please center the content of the alert box, there is too much empty space on the right side of it
🔹 You forgot to bring along the condition for showing the alert box or not (props.defaultAccount === null). It is now always shown, even when MetaMask is connected to the right network.