100Vw Causing Horizontal Overflow, But Only If More Than One

100vw causing horizontal overflow, but only if more than one?

As already explained by wf4, the horizontal scroll is present because of the vertical scroll. which you can solve by giving max-width: 100%.

.box {
    width: 100vw;
    height: 100vh;
    max-width:100%;  /* added */
}

Working Fiddle

Prevent 100vw from creating horizontal scroll

Basically the answer is no, if you have a vertical scrollbar there is no way to make 100vw equal the width of the visible viewport. Here are the solutions that I have found for this issue.

warning: I have not tested these solutions for browser support

tl;dr

If you need an element to be 100% width of the visible viewport(viewport minus scrollbar) you will need to set it to 100% of the body. You can't do it with vw units if there is a vertical scrollbar.

1. Set all ancestor elements to position static

If you make sure that all of .box's ancestors are set to position: static; then set .box to width: 100%; so it will be 100% of the body's width. This is not always possible though. Sometimes you need one of the ancestors to be position: absolute; or position: relative;.

Example

2. Move the element outside of non-static ancestors

If you can't set the ancestor elements to position: static; you will need to move .box outside of them. This will allow you to set the element to 100% of the body width.

Example

3. Remove Vertical Scrollbar

If you don't need vertical scrolling you can just remove the vertical scrollbar by setting the <html> element to overflow-y: hidden;.

Example

4. Remove Horizontal Scrollbar
This does not fix the problem, but may be suitable for some situations.

Setting the <html> element to overflow-y: scroll; overflow-x: hidden; will prevent the horizontal scrollbar from appearing, but the 100vw element will still overflow.

Example

Viewport-Percentage Lengths Spec

The viewport-percentage lengths are relative to the size of the
initial containing block. When the height or width of the initial
containing block is changed, they are scaled accordingly. However,
when the value of overflow on the root element is auto, any scroll
bars are assumed not to exist. Note that the initial containing
block’s size is affected by the presence of scrollbars on the
viewport.

It appears that there is a bug because vw units should only include the scrollbar width when overflow is set to auto on the root element. But I've tried setting the root element to overflow: scroll; and it did not change.

Example

Best solution to remove horizontal scrollbar with img width of 100vw?

The horizontal scroll had come up because this is only an issue on windows. On Mac or Android the scrollbars are placed on top of the content and disappear once you're done scrolling so they don't affect the view width.

If max-width: 100% is the width of the viewport without scrollbars, then you didn't need 100vw in the first place.

You could just have use width: 100% because the element doesn't have any positioned ancestor, so its reference is the body.

A simple solution in your case is by giving max-width: 100%.

HTML would be like:

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

Use this CSS:

html, body {
    margin: 0;
    padding: 0
}
    .box {
        width: 100vw;
        max-width:100%; // This is very Important.
        height: 100vh;
    }

Why there is a scroll on x-axis when width is 100vw?

Because setting width to 100vw will give 100vw width to the element + any padding or margins which results in overflow

100vw element = 100vw width + padding + margin

which is not the case with 100%;

100% element = 100% width inclusve of margin + padding

Mostly the reason is body margin. So set body -> margin to 0 and see it working as 100%.

100vw image inside of 1024px container causing small horizontal scroll

The simplest answer would be to implement overflow-x: hidden; on your body tag itself. If you have no use case where the site should scroll horizontal then there shouldn't be any issue.

100Vw Causing Horizontal Overflow, But Only If More Than One