需要在一侧有半宽边框，在另一侧有全宽边框

Question

Here is my html and css code:

 .image-box{ max-width: 300px; position: relative; }.image-box img{ max-width: 100%; width: 100%; object-fit: cover; border: 8px solid #000000; border-right: 0; border-bottom: 0; /* border-image: linear-gradient(to right, #000 68%, transparent 32%) 100% 1; */ }

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300" alt=""> </figure> </div>

While running this, I receive this.

But, I want to have something like this:

If I uncomment this line

border-image: linear-gradient(to right, #000 68%, transparent 32%) 100% 1; 

Then it shows half width border on top, but this also make the left border disappear and show like this.

Answer 1

You can do something like this using pseudo classes to make the border at the top like how you want it to be achieved:

What it does is hide the half of the border at the top.

 .box { width: 150px; height: 150px; background-color: black; border-top: 5px solid red; border-left: 5px solid red; position: relative; }.box:after { content: ""; width: 50%; height: 5px; background-color: white; position: absolute; right: 0; top: -5px; }

 <div class="box"></div>

Answer 2

Disclaimer : Not an exhaustive list. Try to come up with yet another solution!

With background-image: linear-gradient()

To make a linear-gradient look like a border, we can add padding to the image and a hard color-stop to the gradient:

 .image-box { --thickness: 8px; }.image-box img { padding-top: var(--thickness); padding-left: var(--thickness); background-image: linear-gradient(to right, black 60%, white 60%); } figure{margin:0;line-height:0}

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300"> </figure> </div>

A potential problem with this is that only one side of the border may be shorter.

With Pseudo-elements

Pseudo-elements can be used for presentational styling. You can easily identify them in your CSS by their double-colons (eg ::before , ::marker ).

Sidenote : While still supported for legacy reasons, they can also be written with a single-colon (eg :before ). Do yourself a favour and use the double-colons.

We can use pseudo-elements to create the border.

I will use custom properties to make the code easier to change.
Personally, I enjoy the method Placing behind the most, because that way no bleeding through of the parent's background should happen in extreme (zoom) cases.

Composition

Composite the border with ::before for the left and ::after for the top side. Since these are separate elements, we can define their width and height individually:

 .image-box::before, .image-box::after { content: ""; position: absolute; top: 0; left: 0; background-color: black; }.image-box::before { /* Left */ width: var(--thickness); height: 100%; }.image-box::after { /* Top */ width: 60%; height: var(--thickness); }.image-box { --thickness: 8px; position: relative; /* Leave space for border */ padding-top: var(--thickness); padding-left: var(--thickness); max-width: 300px; box-sizing: border-box; }.image-box img {max-width:100%} figure{margin:0;line-height:0}

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300"> </figure> </div>

Placing behind

Place the image on top of a pseudo-element to make it look like a (partially wide) border:

 .image-box::before, .image-box>figure { grid-area: 1/1 / 1/1; /* Place both on first grid-cell */ }.image-box::before { content: ""; width: 60%; height: 100%; background-color: black; }.image-box { --thickness: 8px; max-width: 300px; display: grid; }.image-box img { /* Leave space for border */ padding-top: var(--thickness); padding-left: var(--thickness); width: 100%; box-sizing: border-box; } figure{margin:0;line-height:0}

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300"> </figure> </div>

Using clip-path: polygon()

Specify each point of the "top-left corner" shape in polygon() :

 .image-box { position: relative; padding-top: 8px; padding-left: 8px; max-width:300px; }.image-box::before { --thickness: 8px; content: ""; position: absolute; top: 0; left: 0; width: 60%; height: 100%; clip-path: polygon( 0 0, 100% 0, 100% var(--thickness), var(--thickness) var(--thickness), var(--thickness) 100%, 0 100%); background-color: black; } figure {margin:0;line-height:0}

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300"> </figure> </div>

Why not use border ?

Edit : Apparently border-image is a thing. See an example . Bottom section is therefore outdated.

Unfortunately, each side of a border can only be a single color. This means the black & white top border is not possible by only using the border property.

A solution to this would be to redraw over part of the border that we don't want:

 #example { padding: 1rem; background-color: slateblue; }.image-box { --thickness: 8px; position: relative; border: 0 solid black; border-top-width: var(--thickness); border-left-width: var(--thickness); max-width: 300px; }.image-box::after { content: ""; position: absolute; top: calc(-1 * var(--thickness)); right: 0; /* 100% - <length> + <thickness left-side> */ width: calc(100% - 60% + var(--thickness)); height: var(--thickness); background-color: white; } body { display: flex; flex-direction: column; gap: 1rem; } figure{margin:0;line-height:0}

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300"> </figure> </div> <div id="example"> <div class="image-box"> <figure> <img src="https://via.placeholder.com/300"> </figure> </div> </div>

But as you can see, this way we will lose the background of the parent. Hard-coding some color only works if the parent's background is a solid color. If the parent's background is an image, this won't work.

Also, having to tell .image-box the color to draw over with is redundant information (because the background already exists) and would only cause more mental overhead for the developer.

Answer 3

you are almost good with border-image. You need to correctly define the slice.

 .image-box { max-width: 300px; position: relative; }.image-box img { max-width: 100%; width: 100%; object-fit: cover; border: 8px solid #000000; border-right: 0; border-bottom: 0; border-image: linear-gradient(to right, #000 68%, transparent 32%) 1; }

 <div class="image-box"> <figure> <img src="https://via.placeholder.com/300" alt=""> </figure> </div>