Z-index issue using transform scale - css

Question

I have a codepen below. Basically, I'm trying to show a popup on hover of the highlighted circles (red), however some highlighted circles are showing up above some of the popups, even when the popups are always given a higher z-index all the time.
http://codepen.io/Wolfmans55/pen/jPwKqZ
This is the animation used for the popup, which I believe maybe the culprit.
#-webkit-keyframes popup {
0% {
transform: scale(2.5);
}
100% {
transform: scale(0);
}
}

Answer 1

Take out the z-index setting on .white-popup and set a higher z-index on .white-popup:hover .popup and .white:hover.
see jsfiddle
#import url(http://fonts.googleapis.com/css?family=Roboto);
body,
html {
height: 100%;
}
body {
background: #343837;
transition: opacity .25s;
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=0)";
overflow: hidden;
}
.show-body {
opacity: 1;
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=100)";
}
.page {
background: #343837;
font-family: 'Roboto', sans-serif;
font-size: 100%;
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
transition: all 1s;
}
.page-2 {
left: auto;
right: -100%;
background: blue;
}
.prev-page,
.next-page {
position: absolute;
top: 50%;
width: 50px;
height: 50px;
background: red;
}
.next-page {
right: 20px;
}
.prev-page {
left: 20px;
}
.page-wrapper {
position: absolute;
top: 50%;
margin-top: -303px;
width: 100%;
}
.header_section {
text-shadow: 1px 1px 1px #000;
font-size: 2em;
}
h1 {
margin: 0;
}
.blue_title {
color: #54c8e7;
font-weight: normal;
}
.primary_title {
font-size: 4em;
margin-top: -34px;
margin-bottom: 20px;
}
.sub_title {
position: relative;
font-size: 1em;
background: #343837;
padding: 0 4px;
display: inline-block;
}
.sub_title_divider {
border-top: 1px solid #54c8e7;;
position: absolute;
top: 20px;
left: 0;
width: 100%;
}
.city-name {
font-size: 2em;
}
.emphasis {
font-weight: bold;
}
.inlineblock {
display: inline-block;
}
.centertxt {
text-align: center;
}
.pos_rel {
position: relative;
}
.overflow_hidden {
overflow: hidden;
}
.vert_mid {
vertical-align: middle;
}
table {
cursor: pointer;
margin: 0 auto;
border-spacing: 1px;
}
td {
width: 10px;
height: 10px;
border-radius: 50%;
}
.white,
.white-popup {
background: #000;
position: relative;
-webkit-animation: in .25s;
}
.white-popup {
background: red;
}
/*.plan-to {
background: #018c9e;
z-index: 2;
}*/
.white-popup .popup {
cursor: auto;
-webkit-animation: popup .25s forwards;
z-index: 10;
}
.popup {
position: absolute;
width: 100px;
height: 100px;
font-size: 5px;
overflow: hidden;
background: #54c8e7;
z-index:10;
top: -45px;
left: -45px;
padding: 8px;
border: 1px solid #343837;
border-radius: 3px;
box-sizing: border-box;
}
.white-popup:hover .popup {
-webkit-animation: out .25s forwards;
z-index: 50;
}
.white:hover {
-webkit-animation: out .25s forwards;
z-index: 50;
}
#-webkit-keyframes in {
from {background:#fff; transform: scale(1);}
to {background: #54c8e7; transform: scale(2.5);}
}
#-webkit-keyframes out {
0% {background:#fff; transform: scale(1);}
100% {background: #54c8e7; transform: scale(2.5);}
}
#-webkit-keyframes popup {
0% {
transform: scale(2.5);
}
100% {
transform: scale(0);
}
}
.key {
height: 15px;
width: 15px;
border-radius: 50%;
border: 1px solid #ccc;
margin-right: 2px;
}
.key_1 {
background: #54c8e7;
}
.key_2 {
background: #018c9e;
}
.key_3 {
background: #fff;
}
.legend {
text-transform:uppercase;
font-size: 12px;
color: #fff;
margin-bottom: 30px;
}
.legend_item {
margin-left: 15px;
}
#media screen and (min-width: 768px) {
.page-wrapper {
margin-top: -388px;
}
td {
width: 15px;
height: 15px;
}
}

Answer 2

I added the following CSS:
td:hover {
z-index: 1;
}
And inside .white-popup selector, I removed:
z-index: 2;
line.
Seems to work for me.