Summary
The issue at hand is creating a gradient mask/slice effect where the active tab appears to be a “window” into the parent container’s gradient background. The desired behavior is for the active tab to match the parent gradient perfectly, without having a separate gradient. The current implementation results in the active tab’s gradient looking different from the parent’s.
Root Cause
The root cause of this issue lies in the way the background-position and background-size properties are used in the .tab.on::before pseudo-element. The current implementation sets the background-size to var(--w) 100%, which is the width of the parent container, and the background-position to var(--x) 0, which is a percentage value based on the active tab. However, this approach does not accurately replicate the parent container’s gradient.
Why This Happens in Real Systems
This issue occurs in real systems due to the following reasons:
- Incorrect background sizing: The background size is set to the parent container’s width, which may not be the correct size to replicate the gradient.
- Inaccurate background positioning: The background position is set based on a percentage value, which may not accurately align with the parent container’s gradient.
- Lack of gradient synchronization: The active tab’s gradient is not synchronized with the parent container’s gradient, resulting in a mismatch.
Real-World Impact
The real-world impact of this issue includes:
- Visual inconsistencies: The active tab’s gradient appears different from the parent container’s gradient, creating a visual inconsistency.
- User experience issues: The mismatched gradient can affect the user experience, making it difficult for users to understand the active tab’s relationship with the parent container.
- Design limitations: The issue limits the design possibilities, as the active tab’s gradient cannot be accurately replicated to match the parent container’s gradient.
Example or Code
.tab.on::before {
content: "";
position: absolute;
inset: 0;
background: var(--g);
background-size: 100% 100%;
background-position: var(--x) 0;
z-index: -1;
clip-path: inset(0 0 0 0);
}In this example, the background-size is set to 100% 100% to ensure the gradient covers the entire active tab, and the clip-path property is used to clip the gradient to the active tab’s boundaries.
How Senior Engineers Fix It
Senior engineers fix this issue by:
- Using the correct background sizing: Setting the background-size to
100% 100%to ensure the gradient covers the entire active tab. - Synchronizing the gradients: Using the background-position property to synchronize the active tab’s gradient with the parent container’s gradient.
- Clipping the gradient: Using the clip-path property to clip the gradient to the active tab’s boundaries, ensuring a seamless transition between the active tab and the parent container.
Why Juniors Miss It
Juniors may miss this issue due to:
- Lack of understanding of CSS gradients: Limited knowledge of how CSS gradients work and how to manipulate them.
- Insufficient experience with pseudo-elements: Limited experience with using pseudo-elements, such as
::before, to create complex effects. - Inadequate testing: Failing to test the implementation thoroughly, leading to overlooked visual inconsistencies and user experience issues.