How to apply custom animation effect @keyframes in MUI?

I have learnt to use animation in CSS using @keyframe. I however want to write my custom animation code to my React project (using MUI). My challenge is how I can write the Javascript code to custom my animations using the makeStyle() in MUI.

I want to be able to custom the transitions processes in percentages this time around in MUI. I need to be able to write codes like this in makeStyle() but I don't seem to know how to.

@keyframes myEffect {
 0%{
  opacity:0;
  transform: translateY(-200%); 
 }

100% {
  opacity:1;
  transform: translateY(0);
 }
}

Here is an example demonstrating the keyframes syntax within makeStyles:

import React from "react";
import ReactDOM from "react-dom";

import { makeStyles } from "@material-ui/core/styles";
import Button from "@material-ui/core/Button";
import clsx from "clsx";

const useStyles = makeStyles(theme => ({
  animatedItem: {
    animation: `$myEffect 3000ms ${theme.transitions.easing.easeInOut}`
  },
  animatedItemExiting: {
    animation: `$myEffectExit 3000ms ${theme.transitions.easing.easeInOut}`,
    opacity: 0,
    transform: "translateY(-200%)"
  },
  "@keyframes myEffect": {
    "0%": {
      opacity: 0,
      transform: "translateY(-200%)"
    },
    "100%": {
      opacity: 1,
      transform: "translateY(0)"
    }
  },
  "@keyframes myEffectExit": {
    "0%": {
      opacity: 1,
      transform: "translateY(0)"
    },
    "100%": {
      opacity: 0,
      transform: "translateY(-200%)"
    }
  }
}));

function App() {
  const classes = useStyles();
  const [exit, setExit] = React.useState(false);
  return (
    <>
      <div
        className={clsx(classes.animatedItem, {
          [classes.animatedItemExiting]: exit
        })}
      >
        <h1>Hello CodeSandbox</h1>
        <h2>Start editing to see some magic happen!</h2>
        <Button onClick={() => setExit(true)}>Click to exit</Button>
      </div>
      {exit && <Button onClick={() => setExit(false)}>Click to enter</Button>}
    </>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Documentation: https://cssinjs.org/jss-syntax/?v=v10.0.0#keyframes-animation

---

For those who have started using Material-UI v5 and want to know how to do this using Emotion rather than makeStyles, below is an example of one way to do the equivalent styles using Emotion.

/** @jsxImportSource @emotion/react */
import React from "react";
import ReactDOM from "react-dom";

import { css, keyframes } from "@emotion/react";
import { useTheme } from "@mui/material/styles";
import Button from "@mui/material/Button";

const myEffect = keyframes`
  0% {
    opacity: 0;
    transform: translateY(-200%);
  }
  100% {
    opacity: 1;
    transform: translateY(0);
  }
`;
const myEffectExit = keyframes`
  0% {
    opacity: 1;
    transform: translateY(0);
  }
  100% {
    opacity: 0;
    transform: translateY(-200%);
  }
`;

function App() {
  const theme = useTheme();
  const animatedItem = css`
    animation: ${myEffect} 3000ms ${theme.transitions.easing.easeInOut};
  `;
  const animatedItemExiting = css`
    animation: ${myEffectExit} 3000ms ${theme.transitions.easing.easeInOut};
    opacity: 0;
    transform: translateY(-200%);
  `;
  const [exit, setExit] = React.useState(false);
  return (
    <>
      <div css={exit ? animatedItemExiting : animatedItem}>
        <h1>Hello CodeSandbox</h1>
        <h2>Start editing to see some magic happen!</h2>
        <Button onClick={() => setExit(true)}>Click to exit</Button>
      </div>
      {exit && <Button onClick={() => setExit(false)}>Click to enter</Button>}
    </>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

Emotion keyframes documentation: https://emotion.sh/docs/keyframes

V5

In v5, you can use the keyframes function (which is re-exported from emotion by default) to generate the stylesheet for keyframe:

import { styled } from '@mui/material/styles';
import { keyframes } from '@mui/system';

const spin = keyframes`
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
`;

const RotatedBox = styled("div")({
  backgroundColor: "pink",
  width: 30,
  height: 30,
  animation: `${spin} 1s infinite ease`
});

Because both styled/sx prop use emotion internally, you can pass the same style object to the sx prop:

<Box
  sx={{
    backgroundColor: "pink",
    width: 30,
    height: 30,
    animation: `${spin} 1s infinite ease`
  }}
/>

V4

Just some notes on top of @Ryan's answer. If you define the keyframe using makeStyles. Remember to prefix the animation name with $. I missed this small detail the first time and my code didn't work, in the example below

const useStyles = makeStyles({
  "@keyframes fadeIn": {
    "0%": {
      opacity: 0,
      transform: "translateY(5rem)"
    },
    "100%": {
      opacity: 1,
      transform: "translateY(0)"
    }
  },
  selector: {
    animation: "$fadeIn .2s ease-in-out"
  }
});

Instead of

animation: "fadeIn .2s ease-in-out"

It should be

animation: "$fadeIn .2s ease-in-out"

But if you define the keyframe in global scope. The prefix is unnecessary here

const useStyles = makeStyles({
  "@global": {
    "@keyframes fadeIn": {
      "0%": {
        opacity: 0,
        transform: "translateY(5rem)"
      },
      "100%": {
        opacity: 1,
        transform: "translateY(0)"
      }
    }
  },
  selector: {
    animation: "fadeIn .2s ease-in-out" // --> this works
  }
});

Follow this issue on github for more discussion about this.