Create a "complex" background in CSS - html

Question

I would like to know if it is possible to create a background like this in CSS3.
The background should span a header div and the gradient should go from white to black independent of the screen width (always white on the left side and black on the right side).
Reason for not using the image is that it takes longer to load and that I can't get it to resize it's width when making the browser smaller than 1920px (the width of the image).
Have tried linear-gradient but I can't get it to work...
Regards,
Jens

Answer 1

If you also want the black bar at the top you should give dimensions to the background, stop the repeating and also position it where you want (treat it like a normal background image)
div {
background-color: black;
background-image: linear-gradient(to right, white, black);
background-repeat:no-repeat;
background-size:100% 20px; /*full width, 20px height*/
background-position:0 100%; /*gradient at bottom*/
/*just to give size to demo*/
min-height:50px;
}
<div></div>

Answer 2

Here's some CSS for you:
#grad {
background: gray; /* For browsers that do not support gradients */
background: -webkit-linear-gradient(left, white , black); /* For Safari 5.1 to 6.0 */
background: -o-linear-gradient(right, white, black); /* For Opera 11.1 to 12.0 */
background: -moz-linear-gradient(right, white, black); /* For Firefox 3.6 to 15 */
background: linear-gradient(to right, white , black); /* Standard syntax */
}
Source: http://www.w3schools.com/css/css3_gradients.asp

Answer 3

I know the OP's question was answered. But I'll comment here anyway to deliver some more information to create a really more "complex" background.
First is you really can create multiple backgrounds stack on each other:
https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Backgrounds_and_Borders/Using_multiple_backgrounds
Second is you can determine position, size, etc,... of a background-image. And here the concise syntax for it: https://www.w3schools.com/cssref/css3_pr_background.asp.
Why background-image? A basic (and important) theory of background in CSS is: A background of an element can have only 1 background-color, and multiple background-images sit on top of it (even if the background-color is declared after background-image, background-color will be still placed below the background-images), and you can resize, reposition those background-images. And an important thing is linear-gradient is count as a background-image, not background-color. The 2 links above do give all detailed information about it.
Here is a quick demo on a "more complex" background from the OP question using only 1 div HTML:
div {
background:
linear-gradient(to right, white, black) 0 100%/100% 20px no-repeat,
linear-gradient(to left, white, black) 0 0/100% 20px no-repeat,
black;
height: 100px;
}
<div></div>
I'm inspired writing this long comment because from a tutorial
https://levelup.gitconnected.com/how-to-implement-netflix-slider-with-react-and-hooks-bdb9b99d1ce4, there's a section from it there're verbose hacks in HTML and CSS to achieve what I'm able to do within just a single line of CSS background, and I think it's cool to share, isn't it?
/* simpler */
.box {
width: 100%;
height: 100px;
background: linear-gradient(to right,black 0%,black 30%,transparent 75%,transparent 100%), green;
}
/* more complex */
.content {
height: 100px;
position: relative;
}
.background {
display: flex;
height: 100%;
}
.left {
background: black;
width: 30%;
position: relative;
}
.left:before {
content: '';
position: absolute;
background-image: linear-gradient(to right,#000,transparent);
top: 0;
bottom: 0;
left: 100%;
width: 275px;
}
.right {
background: green;
width: 70%;
}
.content-container {
color: white;
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
padding: 30px
}
<!-- simpler -->
<div class="box">
<div class="content-container">content here...</div>
</div>
<hr>
<!-- more complex -->
<div class="content">
<div class="background">
<div class="left">left</div>
<div class="right">right</div>
</div>
<div class="content-container">content here...</div>
</div>