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<html><title>W3.CSS</title><meta name="viewport" content="width=device-width, initial-scale=1"><link rel="stylesheet" href="https://www.w3schools.com/w3css/5/w3.css"><body><div class="w3-container"> <h2>Hover Grayscale</h2> <p>The w3-hover-grayscale class adds a "black and white" effect to an element when you move the mouse over it:</p> <img src="img_snowtops.jpg" class="w3-hover-grayscale" alt="Norway" style="width:50%"> <div class="w3-panel w3-red w3-hover-grayscale"> <p>Hover over me</p> </div></div></body></html>