ant-design/components/collapse/demo/borderless.tsx

import React from 'react';
import { Collapse } from 'antd';

const { Panel } = Collapse;

const text = (
  <p style={{ paddingLeft: 24 }}>
    A dog is a type of domesticated animal. Known for its loyalty and faithfulness, it can be found
    as a welcome guest in many households across the world.
  </p>
);

const App: React.FC = () => (
  <Collapse bordered={false} defaultActiveKey={['1']}>
    <Panel header="This is panel header 1" key="1">
      {text}
    </Panel>
    <Panel header="This is panel header 2" key="2">
      {text}
    </Panel>
    <Panel header="This is panel header 3" key="3">
      {text}
    </Panel>
  </Collapse>
);

export default App;