Develop Reference

How to center a play button on a responsive video element

I am making a video player using the HTML5 video element, I have a play button that will start the video. However my problem is how I can get the play button to sit in the centre of the video. Using position or margins to push the button into the centre of the video will not work, as when you resize the window and therefore the player, the play button will move out of place.
I've tried using positioning - left/top etc, and I've used to margins with the same concept, however these do not work with a responsive video player, I'm lost with how to deal with this and was wondering if anyone had suggestions.

For centering any thing (img, icon, text etc)
.parent_item{
position: relative;
}
.center_item {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
}
.parent_item is your video wrapper class while .center_item is you play icon or button, Also it's responsive.

You need to use media queries of CSS for adding padding and margins for a different size for different devices.
Following media queries will help you to code. Put your padding and margin CSS code inside it for varies device viewports.
<style>
/* Extra small devices (phones, 600px and down) */
#media only screen and (max-width: 600px) {
/* Your CSS Code for this device size */
}
/* Small devices (portrait tablets and large phones, 600px and up) */
#media only screen and (min-width: 600px) {
/* Your CSS Code for this device size */
}
/* Medium devices (landscape tablets, 768px and up) */
#media only screen and (min-width: 768px) {
/* Your CSS Code for this device size */
}
/* Large devices (laptops/desktops, 992px and up) */
#media only screen and (min-width: 992px) {
/* Your CSS Code for this device size */
}
/* Extra large devices (large laptops and desktops, 1200px and up) */
#media only screen and (min-width: 1200px) {
/* Your CSS Code for this device size */
}
/* According to Mobile Orientation */
#media only screen and (orientation: landscape) {
/* Your CSS Code for this device orientation */
}
</style>

Is there a way to know if the user is using a small device similar to flexbox using col-sm?

I was wondering if there is a way to know if the user is using a small device. I want my navigation menu to change if the user is using a small device or if he is using a desktop. I want it to be similar to col-sm

you can use CSS media queries for the responsive website or different size of devices. You can use CSS as according to mobile orientation also.
<style>
/* Extra small devices (phones, 600px and down) */
#media only screen and (max-width: 600px) {
/* Your CSS Code for this device size */
}
/* Small devices (portrait tablets and large phones, 600px and up) */
#media only screen and (min-width: 600px) {
/* Your CSS Code for this device size */
}
/* Medium devices (landscape tablets, 768px and up) */
#media only screen and (min-width: 768px) {
/* Your CSS Code for this device size */
}
/* Large devices (laptops/desktops, 992px and up) */
#media only screen and (min-width: 992px) {
/* Your CSS Code for this device size */
}
/* Extra large devices (large laptops and desktops, 1200px and up) */
#media only screen and (min-width: 1200px) {
/* Your CSS Code for this device size */
}
/* According to Mobile Orientation */
#media only screen and (orientation: landscape) {
/* Your CSS Code for this device orientation */
}
</style>

This is what #media queries are used for in CSS.
#media screen and (max-width:479px) {
.navbar {
// style of .navbar when screen is less than 479px
}
}
#media screen and (min-width:480px) {
.navbar {
// style of .navbar when screen is 480px or larger
}
}

convert two column lay out in slider on mobile view

in my project i am working on two column layout like col-lg-8 col-lg-4 , or col-lg-6 col-lg-6 but i want when it will open in mobile view it will convert in the slider what is best solution make a separate section for mobile view or any best way for doing this
Please help me

You need to look into using media queries. These will allow you to cater your design to the width and height of your screen.
/* Large Devices, Wide Screens */
#media only screen and (max-width : 1200px) {
}
/* Medium Devices, Desktops */
#media only screen and (max-width : 992px) {
}
/* Small Devices, Tablets */
#media only screen and (max-width : 768px) {
}
/* Extra Small Devices, Phones */
#media only screen and (max-width : 480px) {
}
/* Custom, iPhone Retina */
#media only screen and (max-width : 320px) {
}
Media Queries

preventing screen sizes to open a site

I was wondering if it is possible to prevent some screens of showing the contents of my site ?
#media only screen and (max-width: 600px) {
body {
/* Hide Content Or Whatever*/
}}

Yes, you can do that via
#media only screen and (max-width: 600px) {
body {
display: none
}}
Note: #media queries aren't supported by IE8 and below

stopping bootstrap template from shrinking after a certain point

I've been wondering if there is a way to stop bootstrap from shriking after a certain point. I like the way my website looks 700 px width. so is there a way to stop bootstrap from shirking my html after that point?

I think that, as mentioned in question Twitter bootstrap minimum width in responsive layout, you can set min-width CSS property to 700px for any element you don't want to be narrower than 700px.
Say you have a div called "wrapper" that wraps all of your page contents:
<div id="wrapper">
<!-- All contents in here -->
</div>
You can style it like this:
#wrapper {
min-width: 700px;
}
NOTE: If you are using responsive layout, you will also have to comment the styles you want to be disabled in bootstrap-responsive.css file.
So, when using responsive layout, if you want your site to be displayed 700px wide, you will also have to comment the styles under:
#media (min-width: 768px) and (max-width: 979px) {
#media (min-width: 1200px) {
#media (max-width: 480px) {
#media (max-width: 979px) {
#media (min-width: 980px) {
And leave the CSS rules (but removing the #media and the brackets) of styles under:
#media (max-width: 767px) {
Hope that helps!