<ul class="menu">
   <li><label for="menu1">Menu 1</label></li>
   <li><label for="menu2">Menu 2</label></li>
   <li><label for="menu3">Menu 3</label></li>
</ul>

<input type="radio" name="menu" id="menu1">
<div> Conteudo do Menu 1</div>

<input type="radio" name="menu" id="menu2">
<div> Conteudo do Menu 2</div>

<input type="radio" name="menu" id="menu3">
<div> Conteudo do Menu 3</div>

UL{
    border: 0;
    margin: -1px;
    padding: 0px;
    background-color: #eee;
    font-weight: bold;
    text-decoration: none;
    font-size: 100%;
    list-style: none;
    line-height: 0.5;
    border-bottom-right-radius: 0px;
    border-bottom-left-radius: 0px;

    border-top-right-radius: 6px;
    border-top-left-radius: 6px;
}

UL:after, UL:before{
    content: '';
    display: table;
    clear: both;
}
UL LI{
    border: 1px solid #cbc7bd;
    list-style: none;
    float: left;
    position: relative;
    top: 1px;
    margin: 0 .2em 1px 0;
    border-bottom: 0 !important;
    padding: 0;
    white-space: nowrap;

    border-top-right-radius: 6px;
    border-top-left-radius: 6px;
}
UL LI label{
    cursor: pointer;
    padding: .5em 1em;
    text-decoration: none;
    float: left;
}
input[type=radio]{
    height: 0;
    width: 0;
    position: absolute;
    opacity: 0;
}
input:checked + div{
    display: block;
}
div{
    display: none;
    border-width: 0;
    padding: 1em 1.4em;
    background: none;
    margin-top: 0;
    border-top: 0;
    border: 1px solid #d9d6c4;
    background-color: white;

    border-bottom-right-radius: 6px;
    border-bottom-left-radius: 6px;
    border-top-right-radius: 0px;
    border-top-left-radius: 0px;
}

LI:has(input:checked)

LI < input:checked