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why I can not put button element while parent have height with percent?

I have a div with 15% height (height: 15%;)
I can not put set span button of this div. If I use height: 300px; it works well. but with percent height does not work. why?
#parent {
height: 15%;
position: relative;
}
span {
position: absolute;
bottom: 0;
}

You can fill the height of the body by using 100vh;
body {
height: 100vh;
}
#parent {
position: relative;
width: 15%;
height: 15%;
background-color: red;
}
span {
position: absolute;
color: white;
text-align: center;
width: 100%;
bottom: 0;
}
<div id="parent">
<span>Hello</span>
</div>

HTML/CSS Animation - JavaScript

I've been trying to animate a sliding door that is triggered on the click of a button.
Here is my fiddle
I've got two sides of the sliding door. Left side is blue, right side is red. The left side should slide to the left and the right door should slide to the right.
First of all, I'm trying to position the button to the middle of the door. I'm using
#button {
z-index: 2;
position: absolute;
top: 50%;
left: 50%;
}
but still the button appears kind of sideways
But secondly when the button is clicked, both sides of the door should slide out at the same time, but unfortunately only the red door functions correctly.
The blue door is stuck. What am I doing wrong?

You can use simple JQuery animation to do what you require.
FIDDLE
Here is the code:
$("button").click(function() {
$(".one").animate({
left: '0'
});
$(".three").animate({
left: '200px'
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="one" style="background:#98bf21;height:100px;width:100px;position:absolute;left:100px;"></div>
<div class="two" style="background:blue;height:100px;width:100px;position:absolute;left:100px;">
</div>
<div class="three" style="background:red;height:100px;width:100px;position:absolute;left:100px;"></div>
<button style="position:absolute;left:110px;top:50px;">
CLICK ME
</button>

It should be like this
function myMove() {
var elem = document.getElementById("myAnimationRight");
var elem_l = document.getElementById("myAnimationLeft");
var elem_R = document.getElementById("myAnimationRight");
elem_l.className += " opened";
elem_R.className += " opened";
}
#container {
width: 800px;
}
#button {
z-index: 2;
position: absolute;
top: 50%;
left: 50%;
}
#wrapper {
z-index: 1;
position: absolute;
display:inline-block;
width: 810px;
overflow:hidden;
}
#left {
display:inline-block;
width: 400px;
}
#right {
display:inline-block;
width: 400px;
}
#myContainer {
width: 400px;
height: 300px;
position: relative;
background: yellow;
}
#myAnimationLeft {
width: 400px;
height: 300px;
position: absolute;
background-color: blue;
transition:linear all 0.5s;
left:0;
}
#myAnimationRight {
width: 400px;
height: 300px;
position: absolute;
background-color: red;
transition:linear all 0.5s;
right:0;
}
#myAnimationRight.opened{
right:-100%;
transition:linear all 0.5s;
}
#myAnimationLeft.opened{
left:-100%;
transition:linear all 0.5s;
}
<div id="container">
<div id ="button">
<button onclick="myMove()">Click Me</button>
</div>
<div id="wrapper">
<div id ="left">
<div id ="myContainer">
<div id ="myAnimationLeft"></div>
</div>
</div>
<div id ="right">
<div id ="myContainer">
<div id ="myAnimationRight"></div>
</div>
</div>
</div>
</div>
You can handle animation via CSS and just add class opened to elements on button click.

You need to minus half the button width and height to bring it to the center.
If button's width is fixed, its correct to use calc(50% - 50px) as Icewine's answer.
For elements with dynamic widths and heights u can always use:
position: absolute;
top: 50%;
left: 50%;
transform:translateX(-50%) translateY(-50%);
The above code will center the element even if you dont know the height and width of the element.
Example:
body {
padding: 0px;
margin: 0px;
}
div {
width: 100px;
height: 100px;
position: absolute;
top: 50%;
left: 50%;
transform: translateX(-50%) translateY(-50%);
background: red;
}
<div></div>
As for animation, why not use classes and let the CSS handle the animation?
function myMove() {
document.getElementById("myAnimationLeft").className = "DoorOpenLeft";
document.getElementById("myAnimationRight").className = "DoorOpenRight";
}
* {
box-sizing: border-box;
}
body {
margin: 0px;
}
#container {
width: 100%;
}
#button {
z-index: 2;
position: absolute;
top: 50%;
left: 50%;
display: inline-block;
transform: translateX(-50%) translateY(-50%);
}
#wrapper {
z-index: 1;
position: absolute;
width: 100%;
overflow-x: hidden;
clear: both;
}
#left {
display: inline-block;
width: 50%;
float: left;
}
#right {
display: inline-block;
width: 50%;
float: right;
}
#myContainer {
width: 100%;
height: 300px;
position: relative;
background: yellow;
}
#myAnimationLeft {
width: 100%;
height: 300px;
left: 0px;
position: absolute;
background-color: blue;
transition: all 1s ease;
}
#myAnimationRight {
width: 100%;
height: 300px;
left: auto;
right: 0px;
position: absolute;
background-color: red;
transition: all 1s ease;
}
.DoorOpenLeft {
left: -100% !important;
}
.DoorOpenRight {
right: -100% !important;
}
<div id="container">
<div id="button">
<button onclick="myMove()">Click Me</button>
</div>
<div id="wrapper">
<div id="left">
<div id="myContainer">
<div id="myAnimationLeft"></div>
</div>
</div>
<div id="right">
<div id="myContainer">
<div id="myAnimationRight"></div>
</div>
</div>
</div>
</div>

Defining same vars causing issues and for the left door you need to decrease value _pos--
Solution for button
left: calc(50% - 38px);
#container {
width: 810px;
}
#button {
z-index: 2;
position: absolute;
top: 50%;
left: 50%;
}
#wrapper {
z-index: 1;
position: absolute;
display: inline-block;
width: 810px;
}
#left {
display: inline-block;
width: 400px;
}
#right {
display: inline-block;
width: 400px;
}
#myContainer {
width: 400px;
height: 300px;
position: relative;
background: yellow;
}
#myAnimationLeft {
width: 400px;
height: 300px;
position: absolute;
background-color: blue;
}
#myAnimationRight {
width: 400px;
height: 300px;
position: absolute;
background-color: red;
}
<div id="container">
<div id="button">
<button onclick="myMove()">Click Me</button>
</div>
<div id="wrapper">
<div id="left">
<div id="myContainer">
<div id="myAnimationLeft"></div>
</div>
</div>
<div id="right">
<div id="myContainer">
<div id="myAnimationRight"></div>
</div>
</div>
</div>
</div>
<script>
function myMove() {
var _elem = document.getElementById("myAnimationLeft");
var _pos = 0;
var _id = setInterval(_frame, 5);
function _frame() {
if (_pos == 410) {
clearInterval(_id);
} else {
_pos--;
_elem.style.right = _pos + 'px';
_elem.style.left = _pos + 'px';
}
}
var elem = document.getElementById("myAnimationRight");
var pos = 0;
var id = setInterval(frame, 5);
function frame() {
if (pos == 410) {
clearInterval(id);
} else {
pos++;
elem.style.left = pos + 'px';
elem.style.right = pos + 'px';
}
}
}
</script>
JQuery Solution created on #shubhamagrawal's answer.
$(document).ready(function() {
$('button').click(function() {
$("#myAnimationLeft").offset({
left: 0
})
$("#myAnimationRight").offset({
left: $("#myAnimationRight").width()
})
$("#myAnimationLeft").animate({
left: -$("#myAnimationLeft").width()
}, 2000);
$("#myAnimationRight").animate({
left: $("#myAnimationRight").width()
}, 2000);
})
})
body,
html {
margin: 0;
padding: 0;
}
#container {
width: 810px;
position:relative;
overflow:hidden;
height:300px;
}
#button {
z-index: 2;
position: absolute;
top: calc(50% - 11px);
left: calc(50% - 34px);
}
#wrapper {
z-index: 1;
position: absolute;
display: inline-block;
width: 810px;
}
#left {
display: inline-block;
width: 400px;
}
#right {
display: inline-block;
width: 400px;
}
#myContainer {
width: 400px;
height: 300px;
position: relative;
background: yellow;
}
#myAnimationLeft {
width: 400px;
height: 300px;
position: absolute;
background-color: blue;
}
#myAnimationRight {
width: 400px;
height: 300px;
position: absolute;
background-color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="container">
<div id="button">
<button>Click Me</button>
</div>
<div id="wrapper">
<div id="left">
<div id="myContainer">
<div id="myAnimationLeft"></div>
</div>
</div>
<div id="right">
<div id="myContainer">
<div id="myAnimationRight"></div>
</div>
</div>
</div>
</div>

For the button, you need to minus the width and height of the button to center it.
left: calc(50% - 50px); if button width is 100px;
Also, you need to set the parent div above button to position: relative; or the absolute wont work. You should also set a height of the parent div while you are at it.

Scrollbar handles not visible

The scroll-bar handles aren't visible in my page. I've tried setting overflow-x to auto and scroll for both the #cust1 and #cust2 div's.
I also need five div's to have their horizontal scrolling controlled from just one scroll-bar at the bottom of the page. (Div's #one, #two, #three, #four and #custTimeline)I don't want scroll-bars for each customer div.
Please help. https://jsfiddle.net/c71ytuxz/1/
var c = document.getElementById("custTimeline");
var ctx = c.getContext("2d");
ctx.font = "20px Georgia";
ctx.save();
ctx.rotate(-90*Math.PI/180);
var baseLoc = 130;
var hours = ["5AM","6AM", "7AM","8AM","9AM","10AM","11AM","12 NOON","1PM","2PM","3PM","4PM","5PM","6PM", "7PM", "8PM", "9PM", "10PM", "11PM", "12PM"];
for(i = 0; i < hours.length; i++) {
if (i == 0) {
ctx.fillText(hours[i], -120, baseLoc);
}
else {
baseLoc += 90;
ctx.fillText(hours[i], -120, baseLoc);
}
}
ctx.restore();
#header {
position: fixed;
top: 0px;
left: 0px;
width: 100%;
height: 100px;
background: lightgrey;
}
#cust1 {
position: fixed;
left: 0px;
top: 160px;
width: 1500px;
height: 150px;
background: lightgrey;
overflow-x: scroll;
overflow-y: hidden;
margin-bottom: 10px;
}
#one {
width: 8%;
height: 150px;
background: darkgrey;
float: left;
text-align: center;
}
#two {
margin-left: 25%;
width: 35px;
height: 150px;
background: green;
}
#cust2 {
position: fixed;
top: 320px;
left: 0px;
width: 1500px;
height: 150px;
background: lightgrey;
overflow-x: scroll;
overflow-y: hidden;
}
#three {
width: 8%;
height: 150px;
background: darkgrey;
float: left;
text-align: center;
}
#four {
margin-left: 15%;
width: 35px;
height: 150px;
background: green;
}
<canvas id="custTimeline"
width = "1900"
height = "130"
style = "border:3px solid #aaaaaa;">
</canvas>
<div id="cust1">
<div id="one"><p>
Customer 1
</p></div>
<div id="two"></div>
</div>
<div id="cust2">
<div id="three"><p>
Customer 2
</p></div>
<div id="four"></div>
</div>

Since the #cust1 has a width of 1500px, the scroll will only appear when its content gets wider than that, and at the moment it is only 8% (#one) + 25% + 35px (#two) in total.
If you want it to scroll, change this
#cust1 {
position: fixed;
left: 0px;
top: 160px;
width: 100vw; /* changed property */
height: 150px;
background: lightgrey;
overflow-x: scroll;
overflow-y: hidden;
margin-bottom: 10px;
}
#two {
margin-left: 25%;
width: 1000px; /* changed property */
height: 150px;
background: green;
}
Updated fiddle
Updated based on a comment
To have one scroll update another, here is one way, using jQuery.
$(document).ready(function(){
$( window ).scroll(function(){
var position = $( this ).scrollLeft();
$("#first").scrollLeft(position);
$("#second").scrollLeft(position);
});
});

Allow Scrolling in DIV when hovering a fixed element

I have a container div with a button and a car img inside of it. The car moves when the page is scrolled.
When the mouse is hovering over top of the button or img, the scroll wheel no longer works.
I tried adding a gray overlay div to block the hover on the button and car. But this prevents the button from being clicked.
Is there a way to make scrolling work even when the button or image is hovered?
$('#home').on('scroll', function() {
var dist = $(this).scrollTop();
$('#cars').css('left', dist / 2);
});
body {
position : absolute;
height: 90%;
width: 90%;
background: #fff;
}
#overlay {
height: 1200px;
background-color: rgba(255,255,255,0.7);
z-index: 999;
position: relative;
pointer-events: none;
}
#buttons {
width: 150px;
height: 40px;
background-color: yellow;
position: fixed;
text-align: center;
z-index: 5;
cursor: pointer;
}
#home {
position: relative;
top:0px;
width: calc(100% + 25px);
overflow-y: scroll;
background-image: url('images/movie_6.jpg');
height: 400px;
background-color: #000000;
margin-top: 40px;
}
#homeinner {
height: 1800px;
overflow: hidden;
}
#cars {
height: 50px;
position: fixed;
top: 100px;
left: 0;
}
#bar {
height: 80px;
width: calc(100% + 25px);
position: absolute;
background-color:red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<section id="home">
<div id="homeinner">
<button id="buttons" onclick="alert('Log in page!')">
button
</button>
<img id="cars" src="http://www.kindaholidays.com/hotel/img/travel_icon/512x512/car.png" />
<div id="overlay">
</div>
</div>
</section>
<div id="bar">
</div>

I think I realize now that your issue is that when the mouse is over top of the button or car image, mousewheel scrolling does not work. This is because the position of those elements is "fixed". I'm not sure if this is a bug or not. Anyways, you can simulate the fixed position with javascript to get around this issue.
$('#home').on('scroll', function() {
var dist = $(this).scrollTop();
$("#buttons").css("top", dist);
$("#cars").css("top", dist + 100);
$('#cars').css('left', dist / 2);
});
body {
position: absolute;
height: 90%;
width: 90%;
background: #fff;
}
#overlay {
height: 1200px;
background-color: rgba(255, 255, 255, 0.7);
z-index: 999;
position: relative;
pointer-events: none;
}
#buttons {
width: 150px;
height: 40px;
background-color: yellow;
position: absolute;
text-align: center;
z-index: 5;
cursor: pointer;
}
#home {
position: relative;
top: 0px;
width: calc(100% + 25px);
overflow-y: scroll;
background-image: url('images/movie_6.jpg');
height: 400px;
background-color: #000000;
margin-top: 40px;
}
#homeinner {
height: 1800px;
overflow: hidden;
}
#cars {
height: 50px;
position: absolute;
top: 100px;
left: 0;
}
#bar {
height: 80px;
width: calc(100% + 25px);
position: absolute;
background-color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<section id="home">
<div id="homeinner">
<button id="buttons" onclick="alert('Log in page!')">
button
</button>
<img id="cars" src="http://www.kindaholidays.com/hotel/img/travel_icon/512x512/car.png" />
</div>
</section>
<div id="bar">
</div>

How to centre <img> which has a z index?

I am having trouble centering an image, at the moment, it stays to the left. The concept is that when I click the image, the larger version of the image pops us.
HTML:
<div class="photoposition" style="cursor:pointer" onclick="showImage('imagesinsurgent/in21.jpg');">
<img src="imagesinsurgent/in21.jpg" class="scaledownlandscape"/>
<p class="photogalleryp"></p>
</div>
<div id="largeImgPanel" onclick="hideMe(this);">
<img id="largeImg" style="height: 100%; margin: 0; padding: 0;" />
</div>
CSS:
.photoposition{
width: 250px;
height: 250px;
margin-left: 53px;
float: left;
position: relative;
}
.scaledownlandscape{
width: 250px;
object-fit: scale-down;
display: block;
margin: 0 auto;
}
.divspan{
position: absolute;
width: 100%;
height: 100%;
top: 0;
left: 0;
z-index: 1;
}
#largeImgPanel {
visibility: hidden;
position: fixed;
z-index: 100;
top: 0;
left: 0;
width: 500px;
height: 400px;
background-color: rgba(100,100,100, 0.5);
margin-top: 141px;
}
Javascript:
function showImage(imgName) {
document.getElementById('largeImg').src = imgName;
showLargeImagePanel();
unselectAll();
}
function showLargeImagePanel() {
document.getElementById('largeImgPanel').style.visibility = 'visible';
}
function unselectAll() {
if(document.selection) document.selection.empty();
if(window.getSelection) window.getSelection().removeAllRanges();
}
function hideMe(obj) {
obj.style.visibility = 'hidden';
}

Give #largeImgPanel 100% width and center align the content
#largeImgPanel {
visibility: hidden;
position: fixed;
z-index: 100;
top: 0;
left: 0;
right: 0;
width: 500px;
height: 400px;
background-color: rgba(100,100,100, 0.5);
margin-top: 141px;
text-align: center;
}
DEMO