5 Essential Steps to Create Folded Corners with CSS corner-shape
Folded corners add a tactile, paper-like feel to web designs. While clip-path is a popular approach (as demonstrated by Kitty Giraudel), the newer corner-shape property offers a more streamlined method—no clipping masks needed. In this guide, we’ll break down the technique into five manageable steps, from setting up CSS variables to animating the fold. Chrome’s experimental support for corner-shape makes this a cutting-edge effect you can start using today. Let’s fold!
1. Understand the corner-shape Property
Before diving into code, grasp what corner-shape does. It controls how a corner is drawn between the coordinates set by border-radius. By default, corners are rounded (corner-shape: round). But you can switch to bevel to draw a straight line between the two coordinates, creating a crisp fold. This property is supported in Chrome (behind a flag) and is perfect for mimicking paper folds without complex clipping. For a deeper dive, check out our next step on variables.
2. Set Up CSS Variables for Coordinates
Every corner has two coordinates: one along the x-axis and one along the y-axis. Storing them as CSS variables makes the effect reusable and animatable. For example, --x-coord: 9rem; and --y-coord: 5rem; define the fold size. These values are used in border-radius and later for the flip side. Variables also keep the code DRY and allow easy adjustments. In the next step, we’ll apply them to create the bevel.
3. Apply border-radius and corner-shape to Create the Fold
With variables ready, target the top-right corner using border-top-right-radius: var(--x-coord) var(--y-coord);. Then set corner-top-right-shape: bevel; to draw a straight line between those two points. This instantly transforms the rounded corner into a triangular fold. The rest of the element remains square. This combination is the core of the folded corners effect. For the flip side, see step 4.
4. Build the Flip Side with a Pseudo-Element
To complete the illusion, create a matching triangle that simulates the back of the fold. Use the ::before pseudo-element with content: "";. Set its width and height to the same x and y coordinates, inherit the background, and add a subtle box-shadow for depth. Position it behind the fold using negative margins or absolute positioning. This flip side gives the paper-like look. For animation tips, jump to step 5.
5. Animate the Fold for Interactive Appeal
Because we used CSS variables, animating the fold is straightforward. Transition the --x-coord and --y-coord values on hover or with scroll-driven animations. The flip side’s dimensions and shadow will update automatically, creating a smooth unfolding effect. Combine with transitions for a polished touch. Browser support for corner-shape is still limited to Chrome, so ensure a graceful fallback to rounded corners.
Folded corners add a delightful micro-interaction to UI elements. With CSS corner-shape and a few variables, you can achieve this effect without extra markup. Experiment with different coordinate ratios and shadow styles to match your design. As browser support grows, this technique will become a standard tool in every developer’s kit. Happy folding!