transition not working on opacity

Question

So I have a header with two buttons, login and join, and I have it so that when the user hovers over one of the buttons, and drops a container with a few inputs and a button. I want the dropdown to fade in with css opacity but I can't get it to work Maybe there is some other better way. Thanks, and here's a fiddle.

HTML:

<div id="membership_container">
    <div id="login_button">
        <span id="login_text">Login</span>
        <div class="form_containers" id="login_box">
            <div class="form_inner_containers">
                <form action="/login" method="POST">
                    <input class="inputs" placeholder="Email" type="text" name="login_email"/>
                    <input class="inputs" placeholder="Password" type="password" name="login_password"/>
                    <input class="buttons" type="submit" value="Login"/>
                </form>
            </div>
        </div>
    </div><!--
    --><div id="join_button">
        <span id="join_text">Join</span>
        <div class="form_containers" id="join_box">
            <div class="form_inner_containers">
                <form action="/join" method="POST">
                    <input class="inputs" placeholder="Your Name" type="text" name="name"/>
                    <input class="inputs" placeholder="Email" type="text" name="email"/>
                    <input class="inputs" placeholder="Password" type="password" name="password"/>
                    <input class="buttons" type="submit" value="Join"/>
                </form>
            </div>
        </div>
    </div>
</div>

CSS:

#membership_container {
    float: right;
    position: relative;
    vertical-align: top;
    display: inline-block;
    height: 100%;
    margin: 0px;
    padding: 0px;
    background-color: #444444;
    text-align: center;
}
#login_button {
    position: relative;
    vertical-align: top;
    display: inline-block;
    float: left;
    height: 100%;
    margin: 0px;
    padding: 0px 10px;
    background-color: #444444;
    border-left: 2px solid #7B7B7B;
    border-right: 2px solid #7B7B7B;
    cursor: pointer;
    cursor: hand;
}
#login_button:hover {
background-color: #696969;
}
#login_button #login_box {
display: none;
opacity: 0.0;
}
#login_button:hover #login_box {
display: block;
opacity: 1;
}
#login_text {
    position: relative;
    margin: 9px 0px 0px;
    text-align: center;
    color: white;
    display: inline-block;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 13px;
}
#join_button {
    position: relative;
    vertical-align: top;
    display: inline-block;
    float: left;
    height: 100%;
    margin: 0px;
    background-color: #444444;
    padding: 0px 10px;
    border-right: 2px solid #7B7B7B;
    cursor: pointer;
    cursor: hand;
}
#join_button:hover {
background-color: #696969;
}
#join_button:hover #join_box {
display: block;
opacity: 1.0;
}
#join_text {
    position: relative;
    margin: 9px 0px 0px;
    text-align: center;
    color: white;
    display: inline-block;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 13px;
}

.button_blur {
    background-color: #444444;
}
.button_blur:hover {
    background-color: #696969;
}
.button_focus {
    background-color: #696969;
}
.form_containers {
    z-index: 10;
    position: absolute;
    display: none;
    opacity: 0.0;
    border: 5px solid #888888;
    border-radius: 10px 0px 10px 10px;
    background-color: #F1F1F1;
    -o-transition: opacity .8s linear;
    -ms-transition: opacity .8s linear;
    -moz-transition: opacity .8s linear;
    -webkit-transition: opacity .8s linear;
    transition: opacity .8s linear;
}
#login_box {
    top: 35px;
    right: -2px;
    /*left: -115px;*/
}
#join_box {
    top: 35px;
    right: -2px;
    /*left: -73px;*/
}
.form_inner_containers {
    position: relative;
    margin: auto auto;
    display: block;
    background-color: #F1F1F1;
    border-radius: 10px;
    border: 0px;
}
.form_hidden {
    display: none;
}
.form_shown {
    display: block;
}
.inputs {
    border-radius: 8px;
    background-color: white !important;
    outline: none;
    border: 0px;
    font-size: 22px;
    padding: 10px;
    margin: 10px;
    box-shadow: 0px 0px 0px grey;
}
.inputs:focus {
    box-shadow: 3px 3px 3px grey;
}
.buttons {
    position: relative: 
    display: block;
    background-color: #00ADEF;
    margin: 10px;
    border-radius: 8px;
    padding: 10px 15px 8px;
    width: 269px;
    outline: none;
    font-size: 22px;
    border: 0px;
    cursor: pointer;
    cursor: hand;
    color: #F1F1F1;
}
.buttons:hover {
    background-color: #18B4EF;
}
.buttons:active {
    background-color: #91D6F0;
    color: #F1F1F1;
    outline: none;
}

Answer 1

If you set the max-height to 0px with overflow hidden it will be as if it is display none and will not show.

Then when the state changes set max-height to something large (big enough to contain the area) like 400px. It will then appear as if it was hidden none to hidden block.

.form_before_state_change {
max-height:0px;
overflow:hidden;
opacity: 0;
-o-transition: opacity .8s linear;
-ms-transition: opacity .8s linear;
-moz-transition: opacity .8s linear;
-webkit-transition: opacity .8s linear;
transition: opacity .8s linear;
}

.form_after_state_change {
    max-height:400px;
    opacity: 1;
}

Answer 2

Okay, thanks to this link that someone commented, I've come up with the following css which works great. I've decided I like it better if there is no fade in and out, but simply a delay, but I still use the css transition for it:

#membership_container {
    float: right;
    position: relative;
    vertical-align: top;
    display: inline-block;
    height: 100%;
    margin: 0px;
    padding: 0px;
    background-color: #444444;
    text-align: center;

}
#login_button {
    position: relative;
    vertical-align: top;
    display: inline-block;
    float: left;
    height: 100%;
    margin: 0px;
    padding: 0px 10px;
    background-color: #444444;
    border-left: 2px solid #7B7B7B;
    border-right: 2px solid #7B7B7B;
    cursor: pointer;
    cursor: hand;
}
#login_button:hover {
    background-color: #696969;
}
#login_button:hover #login_box {
    visibility: visible;
    opacity: 1;
    transition-delay: .5s;
}
#login_text {
    position: relative;
    margin: 9px 0px 0px;
    text-align: center;
    color: white;
    display: inline-block;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 13px;
}
#join_button {
    position: relative;
    vertical-align: top;
    display: inline-block;
    float: left;
    height: 100%;
    margin: 0px;
    background-color: #444444;
    padding: 0px 10px;
    border-right: 2px solid #7B7B7B;
    cursor: pointer;
    cursor: hand;
}
#join_button:hover {
    background-color: #696969;
}
#join_button:hover #join_box {
    visibility: visible;
    opacity: 1.0;
    transition-delay: .5s;
}
#join_text {
    position: relative;
    margin: 9px 0px 0px;
    text-align: center;
    color: white;
    display: inline-block;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 13px;
}

.button_blur {
    background-color: #444444;
}
.button_blur:hover {
    background-color: #696969;
}
.button_focus {
    background-color: #696969;
}
.form_containers {
    z-index: 10;
    position: absolute;
    opacity: 0;
    visibility: hidden;
    border: 5px solid #888888;
    border-radius: 10px 0px 10px 10px;
    background-color: #F1F1F1;
    -o-transition: visibility 0s linear .5s, opacity 0s linear .5s;
    -ms-transition: visibility 0s linear .5s, opacity 0s linear .5s;
    -moz-transition: visibility 0s linear .5s, opacity 0s linear .5s;
    -webkit-transition: visibility 0s linear .5s, opacity 0s linear .5s;
    transition: visibility 0s linear .5s, opacity 0s linear .5s;
}
#login_box {
    top: 35px;
    right: -2px;
    /*left: -115px;*/
}
#join_box {
    top: 35px;
    right: -2px;
    /*left: -73px;*/
}
.form_inner_containers {
    position: relative;
    margin: auto auto;
    display: block;
    background-color: #F1F1F1;
    border-radius: 10px;
    border: 0px;
}
.form_hidden {
    display: none;
}
.form_shown {
    display: block;
}

Answer 3

The contains are set to "display: none;" to hide them. On hover, they are set to "display: block" which immediately displays them and ignores the opacity transition. Personally, I find this "bug" very irritating (it isn't a bug...but, it's annoying).

Two work arounds are Javascript (messy) and using CSS Keyframe animations. http://hschwarz77.wordpress.com/2013/10/16/css-transition-from-display-none-to-display-block-on-hover/

To the best of my knowledge, these are the only solutions to have the div completely hidden (and unusable...visibility:hidden occupies the space) and fade in.

Answer 4

display: none; on all of those elements are screwing up your transitions. You can't put a css transition on display none because it's either true or false and there's no in between.

Here's a JSFiddle