class MyComponent extends HTMLElement {
    constructor() {
        super();

        const shadowRoot = this.attachShadow({mode: "open"});

        shadowRoot.innerHTML = `
            <style>
                :host {
                    display: block;
                }
                
                .inner {
                    /* Inner Styles */
                }
            </style>
            
            <div class="inner">Web Component Text with inner class</div>
            <div class="outer">Web Component Text with outer class</div>    
        `;
    }
}

window.customElements.define("my-component", MyComponent);