<form >
<input type="radio" name="name" id="r-1" class="input" checked>
<input type="radio" name="name" id="r-2" class="input">
<input type="radio" name="name" id="r-3" class="input">
<label for="r-1" class="label l-1">Текст 1</label>
<label for="r-2" class="label l-2">Текст 2</label>
<label for="r-3" class="label l-3">Текст 3</label>
</form>
.label {
display: none;
}
#r-1:checked~.l-1,
#r-2:checked~.l-2,
#r-3:checked~.l-3{
display: block;
}