is there any guideline for making a true responsive modal windows?

I am making a modal windows,
However, I found that determine width,height of an object by using percentage is not suitable.
So, is there any guideline for making a true responsive modal windows?
I attached my work for your reference.
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Ares KurkluSoftware EngineerCommented:
Do you want to do it yourself? may be easier to use bootstrap or jquery
KNVB HKSITOAuthor Commented:
I am using jAlert, however it cannot accept a DOM object as content, therefore I want to build it by myself.

Any other jquery plugin can accept a DOM object as content are welcome also.
Ares KurkluSoftware EngineerCommented:
Not sure what you are trying to do exactly but how about the 2nd one jquery dialog?
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KNVB HKSITOAuthor Commented:
I need to set an unsorted list (i.e. ul) as content.
When each list item on click , I want to call my JavaScript object class, however, the inline on click handler cannot found my JavaScript object class, that is my problem.
Julian HansenCommented:
What you are probably needing to do is combine % height / width with media queries

Media queries enable you to change the style of an element depending on the metrics of the screen.

The general rule of thumb is to create your modal for mobile first
width 100% 

Open in new window

Then for the next size screen
@media (min-width: 768px) {
   .modal {
       width: 75%;
@media (min-width: 1024px) {
   .modal {
       width: 50%;

Open in new window

The above is for illustration purposes only - it is demonstrating how you can modify styles based on size of screen starting from a base (mobile) and then amending as the screen size increases. Obviously you can add other styles (other than width) to the above as required.
KNVB HKSITOAuthor Commented:
I solved the problem by using flexbox.
However, MS Edge browser seem does not support overflow css attribute.
Currently, I cannot solve this problem.
Please find attached my work.
KNVB HKSITOAuthor Commented:
Finally, I got what I want.

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KNVB HKSITOAuthor Commented:
That is what I want.
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