background image doesn't scale to fit the site - css

Live demo: http://leoaivy.github.io/projects/poster_inside/html/1_P.01_login.html
Questoin: ".login-bg-wrap a img" work well on desktop with max-width set to 100%. But on narrower devices like iphone 6, the background images just scale to fit the width of view port, which make their height become smaller. I set heihgt to just 1% or 100% but they scale to their original size. I don't know why? And is there a way to make the height of these images fit the height of the site?

You need to make sure that every element, down to the images, is set to have a width of 100%. And an extra min-width of whatever number you want to stop the shrinking at applied to the image itself.
And only the width, not the height.

You could remove the max-width, make the image's height and width 100%, and give it a object-fit: cover; Is that what you are trying to achieve?
You can also use 100vw on the width, and 100vh on the height, so that way the image will always have the viewport's size.

Related

how to make a div take full screen size and stop it from shrinking

I have a with a className container,
if I do this :
.container{
height:100vh
}
whenever I shrink my screen size, for example with dev-tools, the div shrinks as well, how do I stop it from happening? I want it to be full screen always, is that possible?
When I understand your question correctly, then the shrinking of the div when resizing the screen is the correct behaviour. vh stands for viewport height. That means the height stands to the exact relation of the height of your whole screen. If you want the size fixed you have to use px or rem.
the height being 100vh is the correct answer to have a fullscreen height, perhaps u have other properties in child elements that are causing the div to shrink.

Width and max-width (css)

I was reading an article explaining the css properties width and max-width and came across this example:
img {
width: 100%;
max-width:700px;}
This says that the fixed width of the image, should take up the entire size of the parent element — if the width of the parent element is explicitly stated, — all hundred percent of it, yet the image should never exceed 700px. It means that the image can be less than 700px, if that suits its situation better (e.g smaller window size) but it should never be more. So there are two conditions here, that the width of the image can be 100% of the parent element if it wants to but it must not never be more than 700px.
But isn't it unnecessary to add the width:100% here? Doesn't max-width:700px imply that the width will be 100% if the parent is less than 700px anyway?
First, width defines the width of a specific element while max-width define the maximum size the element is allowed to have.
Second, width:100% use the parent's width to calculate the current width value whereas max-width:100% use its own original width to calculate the maximum size. So, the image with width: 100% could be larger its original size (scaled base on its parent width). On the other hand, the image with max-width: 100% could be smaller but never be scaled larger its original size (maximum valid width = 100% x original width). That's why it's called fluid image.
Let's say you put width: 700px for an image. When you re-size your screen the image stays stably 700px. Let's say you on a mobile phone and its screen width is less then 700px the image will not fit in the screen. So it will stretch out your page and make it not mobile-friendly. At the same time, when you set max-width:700px it will re-size up to 700px but when the screen goes smaller and the images don't fit in the screen it will automatically re-size it to fit the screen.
As far I understand you want to get the image fit to the size of its parent container with the constraint of not exceeding the width of the image more than 700px.
Then I will say yes it is unnecessary to give "width: 100%;" either way default value for width will get selected i.e. "auto".
Because of this whenever your parent container will be smaller than 700px, your image will fit your container (since "width: auto;").
P.S.-Please refer "object-fit: contain" property of CSS, as that will also help.

Css image resize by height, keep aspect ratio and max-width

I've a big image and I want to resize it by height (fixed). Width has to keep the aspect ratio, but I want that only a max-width of the image is shown. Is it possible to do this with a single css div?
Yes put in max-height instead of height

CSS: Set an image as background, keep its size unchanged

I'm using a big image as background. However, it always resize automatically(Can't display full height of the img), How to deal with it?
One way is to set its height to the image's height. But when I'm reuse the class for other images, I have to change the height many times.
#HTML
div.img-bg
div.content
#CSS
.img-bg
background-image: .....
DEMO
Try background-size: auto; (the default value)
If you do not resize the background-image and use it's full size, your div.content should be as big as the image height.
So, as far as i understood, you set width to .content, now you can try to set height or min-height to fit the background-image's height.
Without height setted, I guess you have something like on the pic.
UPDATED DEMO

Resizing images based on their original size with CSS

I'm making a responsive blog for both mobile and desktop users (all in one). With respect to image resizing, I understand that I can use width:100%; height:100%; so that they scale proportionally depending on the page size, but I've noticed that smaller images upscale to fit the width of the DIV that it is in. Let's say my DIV has a max-width of 640px but an image I include within it in 500px.
What CSS can I use to keep the image at 500px and then scale down proportionally if the resolution width falls below 500px?
The reason I'm asking this is because not all images in posts may be 640px wide.
Set your image max-width property to the actual image size.
Why don't you just set max-width:100% and leave width off.

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