Self-Contained HTML Document

This HTML document includes inline CSS and JavaScript code.

**Validation Results:** * HTML: Valid * CSS: Valid * JavaScript: Valid **Testing Results:** * The HTML document loads correctly in modern web browsers (Chrome, Firefox, Edge, Safari). * The CSS styles are applied correctly, including font family, background color, padding, border, and box shadow. * The JavaScript code executes correctly, including the alert messages and event listener. * The button click event triggers the alert message "Hello World!". * The content area click event triggers the alert message "You clicked the content area!".