styles.css

/* Global Layout Set-up */

* {
    box-sizing: border-box;
}

.photo_gallery {
	margin: 0 auto;
	margin-top: 145px;
	font-size: 0;
	max-width: 980px;
	margin-bottom: 120px;
}

img {
	box-shadow: 0px 0px 10px 0px rgba(0, 0, 0, .1);
  	transition: box-shadow .3s;
}

img:hover  {
  box-shadow: 0px 0px 50px 0px rgba(0, 0, 0, .3);
}

.header-container {
    width: 100%;
	background: white;
	position: fixed;
	top: 0;
	left: 0;
}

#lightgallery a {
  margin: 40px 60px 0 0px;
  font-size: 16px; 
  display: inline-block;
  width: calc(50% - 30px);
}

#lightgallery a:nth-of-type(2n) {
  margin-right: 0;
}

.header {
	text-align: center;
	font-family: 'Indie Flower', cursive;
}

.search-button {

    margin: 30px auto;
    width: 460px;
    display: block;
    -webkit-transition: all 0.30s ease-in-out;
    -moz-transition: all 0.30s ease-in-out;
    -ms-transition: all 0.30s ease-in-out;
    -o-transition: all 0.30s ease-in-out;
    outline: none;
    border: 1px solid #DDDDDD;
    font-size: 16pt;
 
}

.search-button:focus {
  box-shadow: 0 0 5px rgba(81, 203, 238, 1);
  border: 1px solid rgba(81, 203, 238, 1);
}


@media screen and (min-width: 700px) {
  #lightgallery a {
    width: calc(33.33% - 40px);
  }

  #lightgallery a:nth-of-type(1n) {
    margin-right: 60px;
  }

  #lightgallery a:nth-of-type(3n) {
    margin-right: 0;
  }
}


@media screen and (min-width: 980px) {
  #lightgallery a {
    width: calc(25% - 45px);
  }

  #lightgallery a:nth-of-type(1n) {
    margin-right: 60px;
  }

  #lightgallery a:nth-of-type(4n) {
    margin-right: 0;
  }

}