What can we do get a layout like this using just flex?

I want a layout like this, how can I write the CSS code?

My HTML (I have moved my CSS in styles in HTML):

<div class="container" style={{ display: "flex", flexWrap: "wrap" }}><div class="orange" style={{ flex: 1 }}><div id="chart" /></div><div class="yellow" style={{ flex: 1 }}><LineChart        width={600}        height={300}        data={this.state.data2}        margin={{ top: 5, right: 30, left: 20, bottom: 5 }}><XAxis dataKey="name" /><YAxis /><CartesianGrid strokeDasharray="3 3" /><Tooltip /><Legend /><Line          type="monotone"          dataKey="pv"          stroke="#8884d8"          activeDot={{ r: 8 }}        /><Line type="monotone" dataKey="uv" stroke="#82ca9d" /></LineChart></div></div>