“If you just sit and observe, you will see how restless your mind is. If you try to calm it, it only makes it worse, but over time it does calm, and when it does, there’s room to hear more subtle things. You see so much more than you could see before. It’s a discipline; you have to practice it.”
Steve Jobs

<length>

The <length> CSS data type represents a distance value. Lengths can be used in numerous CSS properties, such as width, height, margin, padding, border-width, font-size, and text-shadow.
length#vmax css reference