* { box-sizing: border-box; }

/* force scrollbar */
html { overflow-y: scroll; }

body { font-family: sans-serif; }

/* ---- grid ---- */

#masonry
{
    margin-top: 30px
}

/* clear fix */
.grid:after {
  content: '';
  display: block;
  clear: both;
}

/* ---- .grid-item ---- */

.grid-sizer,
.grid-item {
  width: 100%;
  border: 1px solid #ffff;
}

.grid-item {
  float: left;
}

.grid-item img {
  display: block;
  max-width: 100%;
}

@media only screen and (min-width:768px)
{
    #masonry
{
    margin-top: 50px
}

    .grid-sizer,
.grid-item {
  width: 50%;
  border: 2px solid #ffff;
}
}
@media only screen and (min-width:1340px)
{
    #masonry
{
    margin-top: 70px
}
    .grid-sizer,
.grid-item 
{
  width: 33.333%;
  border: 3px solid #ffff;
}
}
@media only screen and (min-width:1820px)
{
    .grid-sizer,
.grid-item 
{
  width: 25%;
  border: 4px solid #ffff;
}
}