Animation CSS3: display + opacity

Question

Based on Michaels answer this is the actual CSS code to use

.parent:hover .child
{
    display: block;

    -webkit-animation: fadeInFromNone 0.5s ease-out;
    -moz-animation: fadeInFromNone 0.5s ease-out;
    -o-animation: fadeInFromNone 0.5s ease-out;
    animation: fadeInFromNone 0.5s ease-out;
}

@-webkit-keyframes fadeInFromNone {
    0% {
        display: none;
        opacity: 0;
    }

    1% {
        display: block;
        opacity: 0;
    }

    100% {
        display: block;
        opacity: 1;
    }
}

@-moz-keyframes fadeInFromNone {
    0% {
        display: none;
        opacity: 0;
    }

    1% {
        display: block;
        opacity: 0;
    }

    100% {
        display: block;
        opacity: 1;
    }
}

@-o-keyframes fadeInFromNone {
    0% {
        display: none;
        opacity: 0;
    }

    1% {
        display: block;
        opacity: 0;
    }

    100% {
        display: block;
        opacity: 1;
    }
}

@keyframes fadeInFromNone {
    0% {
        display: none;
        opacity: 0;
    }

    1% {
        display: block;
        opacity: 0;
    }

    100% {
        display: block;
        opacity: 1;
    }
}

If possible - use visibility instead of display

For instance:

.child {
    visibility: hidden;
    opacity: 0;
    transition: opacity 0.3s, visibility 0.3s;
}

.parent:hover .child {
    visibility: visible;
    opacity: 1;
    transition: opacity 0.3s, visibility 0.3s;
}

You can do with CSS animations:

0% display:none ; opacity: 0;
1% display: block ; opacity: 0;
100% display: block ; opacity: 1;

This workaround works:

1. define a “keyframe”:

   @-webkit-keyframes fadeIn { 
     0% { opacity: 0; }
     20% { opacity: 0; }
     40% { opacity: 0.3; }
     60% { opacity: 0.5; }
     80% { opacity: 0.9; }
     100% { opacity: 1; }
   }
   
   @keyframes fadeIn {
     0% { opacity: 0; }
     20% { opacity: 0; }
     40% { opacity: 0.3; }
     60% { opacity: 0.5; }
     80% { opacity: 0.9; }
     100% { opacity: 1; }
   }
   

2. Use this “keyframe” on “hover”:

   div a span { 
     display: none;
   }
   
   div a:hover span {
     display: block;
   
     -webkit-animation-name: fadeIn;
     -webkit-animation-duration: 1s;
     animation-name: fadeIn;
     animation-duration: 1s;
   }
   

I used this to achieve it. They fade on hover but take no space when hidden, perfect!

.child {
    height: 0px;
    opacity: 0;
    visibility: hidden;
    transition: all .5s ease-in-out;
}

.parent:hover .child {
    height: auto;
    opacity: 1;
    visibility: visible;
}

I changed a bit but the result is beautiful.

.child {
    width: 0px;
    height: 0px;
    opacity: 0;
}

.parent:hover child {
    width: 150px;
    height: 300px;
    opacity: .9;
}

Thank you to everyone.

There is another good method to get this done by using pointer-events:

.child {
    opacity: 0;
    pointer-events: none;

    -webkit-transition: opacity 0.5s ease-in-out;
    -moz-transition: opacity 0.5s ease-in-out;
    transition: opacity 0.5s ease-in-out;
}

.parent:hover .child {
    opacity: 0.9;
    pointer-events: all;
}

Unfortunately, this is not supported in IE10 and below.