bootstrap versión 3.3.6
.columna{
width: 39%;
padding: 2% 15px 2% 15px; /* alineado en vertical */
margin: 2%;
text-align: left;
display: inline-block;
box-shadow: 0 1px 2px rgba(0,0,0,0.25);
background-color: #DDDDDD;
}

Referenciar TODAS las class .columna

function fMostrarTodo(){
var x = document.querySelectorAll(".columna");
var i;
for (i = 0; i < x.length; i++) {
x[i].style.visibility = "visible";
x[i].style.display = "";
}}

https://www.w3schools.com/js/js_htmldom_elements.asp