Front End Development Libraries Projects - Build a Markdown Previewer

Element not responding to the new classes added
I created the markdown app alright but I wanted to add some functionality like maximising the #editor element while hiding the #preview and vice versa.
My idea was to add or remove .full and .hidden based on the state of the react component and then mutate these states with some functions.
However, the elements are not responding correctly to the added class.
I tried useRef at first but it keeps breaking my app.

If there is a better way to accomplish this, please let me know.

My code so far

HTML
<div id='app'></div>

CSS

#first {
  display: flex;
  flex-direction: column;
  // justify-content: center;
  position: absolute;
  background-color: #122123;
  top: 10px;
  margin-top: 10px;
  margin-left: 10px;
  width: auto;
  height: auto;
  border: 2px solid black;
}
i {
  font-size: 2rem;
  color: brown;
}
button {
  margin-right: 10px;
  display: inline-block;
  background-color: inherit;
}
.title {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 0;
  height: 50px;
  background: black;
  color: brown;
  // padding: auto 20px;
  h2 {
    text-align: left;
    font-family: "Russo One" !important;
    font-style: oblique !important;
    font-weight: 700 !important;
    font-size: 2em !important;
    margin-left: 10px;
  }
}

#editor {
  border: none;
  width: 400px;
  height: 400px;
  overflow: auto;
  resize: none;
  background-color: #122123;
}

#second {
  position: absolute;
  background-color: #122123;
  top: 20px;
  right: 10px;
  min-height: 300px;
  max-height: auto;
  width: 700px;
  border: 2px solid black;
}

textarea:focus {
  outline: none;
}
#preview {
  padding: 0 1rem;

  blockquote {
    border-left: 3px solid #224b4b;
    color: #224b4b;
    padding-left: 5px;
    margin-left: 25px;
  }

  > p > code {
    padding: 3px;
  }

  code {
    background: white;
    font-size: 0.875rem;
    font-weight: bold;
  }

  pre {
    display: block;
    overflow: auto;
    background: white;
    padding: 5px;
    line-height: 1.2;
  }

  h1 {
    border-bottom: 2px solid black;
  }

  h2 {
    border-bottom: 1px solid black;
  }

  table {
    border-collapse: collapse;
  }

  td,
  th {
    border: 2px solid black;
    padding-left: 5px;
    padding-right: 5px;
  }

  img {
    display: block;
    max-width: 90%;
    margin: 2rem auto;
  }
}
.hidden {
  display: none;
}
.full {
  width: 95%;
  min-height: 80vh;
  max-height: auto;
}

JS(babel)

// marked.setOptions({
//   gfm: true,
//   breaks: true,
//   sanitize: true
// });
// const renderer = new marked.Renderer();
// renderer.link = function (href, title, text) {
//   return `<a target="_blank" href="${href}">${text}</a>`;
// };

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      editor: placeholder,
      maxEditor: false,
      maxPreview: false,
      hideEditor: false,
      hidePreview: false,
      minBtn: true,
      maxBtn: false
    };
    this.handleChange = this.handleChange.bind(this);
    this.maxEditor = this.maxEditor.bind(this);
    this.minEditor = this.minEditor.bind(this);
    this.maxPreview = this.maxPreview.bind(this);
    this.minPreview = this.minPreview.bind(this);
  }

  handleChange(event) {
    this.setState({
      editor: event.target.value
    });
    console.log(document.getElementById('first').classList)
    console.log(document.getElementById('second').classList)
  }
  maxEditor(event) {
    this.setState({
      maxEditor: !this.state.maxEditor,
      hidePreview: !this.state.hidePreview,
      minBtn: !this.state.minBtn,
      maxBtn: !this.state.maxBtn
    });
    console.log(document.getElementById('first').classList)
    console.log(document.getElementById('second').classList)
  }
  minEditor(event) {
    this.setState({
      maxEditor: false,
      hidePreview: false,
      minBtn: true,
      maxBtn: false
    });
    console.log(document.getElementById('first').classList)
    console.log(document.getElementById('second').classList)
  }
  maxPreview(event) {
    this.setState({
      maxPreview: true,
      hideEditor: true,
      minBtn: false,
      maxBtn: true
    });
    console.log(document.getElementById('first').classList)
    console.log(document.getElementById('second').classList)
  }
  minPreview(event) {
    this.setState({
      maxPreview: false,
      hideEditor: false,
      minBtn: true,
      maxBtn: false
    });
    console.log(document.getElementById('first').classList)
    console.log(document.getElementById('second').classList)
  }
  render() {
    return (
      <div className="app">
        <div
          className={`markup ${this.state.hideEditor ? "hidden" : ""} ${
            this.state.maxEditor ? "full" : ""
          }`}
          id="first"
        >
          <div className="title">
            <h2>Editor</h2>
            <button
              onClick={this.maxEditor}
              className={`markup-btn increase ${
                this.state.maxBtn ? "hidden" : ""
              }`}
            >
              <i className="fa-solid fa-maximize"></i>
            </button>
            <button
              onClick={this.minEditor}
              className={`markup-btn decrease ${
                this.state.minBtn ? "hidden" : ""
              }`}
            >
              <i className="fa-solid fa-minimize"></i>
            </button>
          </div>
          <textarea
            name="markup-text"
            id="editor"
            value={this.state.editor}
            onChange={this.handleChange}
          ></textarea>
        </div>
        <div
          className={`markup ${this.state.hidePreview ? "hidden" : ""} ${
            this.state.maxPreview ? "full" : ""
          }`}
          id="second"
        >
          <div className="title">
            <h2>Preview</h2>
            <button onClick={this.maxPreview} className={`markup-btn increase ${
                this.state.maxBtn ? "hidden" : ""
              }`}>
              <i
                className="fa-solid fa-maximize"
              ></i>
            </button>
            <button onClick={this.minPreview} className={`markup-btn decrease ${
                this.state.minBtn ? "hidden" : ""
              }`}>
              <i className="fa-solid fa-minimize"></i>
            </button>
          </div>
          <Preview markdown={this.state.editor} />
        </div>
      </div>
    );
  }
}
const renderer = new marked.Renderer();
renderer.link = function (href, title, text) {
  return `<a target="_blank" href="${href}">${text}</a>`;
};

const Preview = (props) => {
  return (
    <div
      dangerouslySetInnerHTML={{
        __html: marked(props.markdown, { renderer: renderer, breaks: true })
      }}
      id="preview"
    />
  );
};

const placeholder = `# Welcome to my React Markdown Previewer!

## This is a sub-heading...
### And here's some other cool stuff:

Heres some code, \`<div></div>\`, between 2 backticks.

\`\`\`
// this is multi-line code:

function anotherExample(firstLine, lastLine) {
  if (firstLine == '\`\`\`' && lastLine == '\`\`\`') {
    return multiLineCode;
  }
}
\`\`\`

You can also make text **bold**... whoa!
Or _italic_.
Or... wait for it... **_both!_**
And feel free to go crazy ~~crossing stuff out~~.

There's also [links](https://www.freecodecamp.org), and
> Block Quotes!

And if you want to get really crazy, even tables:

Wild Header | Crazy Header | Another Header?
------------ | ------------- | -------------
Your content can | be here, and it | can be here....
And here. | Okay. | I think we get it.

- And of course there are lists.
  - Some are bulleted.
     - With different indentation levels.
        - That look like this.


1. And there are numbered lists too.
1. Use just 1s if you want!
1. And last but not least, let's not forget embedded images:

![freeCodeCamp Logo](https://cdn.freecodecamp.org/testable-projects-fcc/images/fcc_secondary.svg)
`;

ReactDOM.render(<App />, document.getElementById("app"));

Link to my codepen
My Markdown Preview App

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

Challenge: Front End Development Libraries Projects - Build a Markdown Previewer

Link to the challenge:

You are styling using ids and then trying to overwrite the styles using a class, ids have higher specificity than classes.

Thank you. All problems solved.