.p-sub-category {
  margin: 30px 10px;
  padding: 0;
  list-style-type:none;
}

.p-sub-category::after {
  display: block;
  clear: both;
  content: '';
}

.p-sub-category__item {
  float: left;
  box-sizing: border-box;
  width: 50%;
  padding: 10px 5px;
}

.p-sub-category__image {
  display: block;
  margin-bottom: 10px;
  box-shadow: 1px 5px 9px -5px rgba(0, 0, 0, 0.2); /*横方向　下方向　ぼかし　広がり　色 */
}

.p-sub-category__link {
  display: block;
  transition: opacity .2s;
  text-decoration: none;
  color: #333;
}

.p-sub-category__link:hover {
  opacity: .66;
}

.p-sub-category__link:active {
  opacity: 1;
}

.p-sub-category__name {
  line-height: 1.3;
  position: relative;
  display: block;
  padding-left: .8em;
}

.p-sub-category__name::before {
  position: absolute;
  top: 0;
  left: 0;
}

@media screen and (min-width: 600px) {
  .p-sub-category {
    margin-right: 0;
    margin-left: 0;
  }

  .p-sub-category__item {
    width: 25%;
    padding: 15px 10px;
  }

  .p-sub-category__item:nth-child(4n + 1) {
    clear: both;
  }
}

@media screen and (max-width: 599px) {
  .p-sub-category__item:nth-child(2n + 1) {
    clear: both;
  }
}

<!-- CSS Grid CSS -->
.flexboxA {
  display: flex;
  flex-wrap: wrap;
  border: 1px solid #ddd;
  padding: 0.4em;
  margin: 0 0 2em;
}

.flexboxA > div {
  background: #f39800;
  padding: 10px 13px;
  flex: 1 0 300px;
  margin: 0.4em;
  border-radius: 10px;
}
.flexboxA > div:hover{
	background-color: #ee7800;
}

.flexboxA a{
	color:#ffffff;
	text-decoration: none;
	display: block;
	}

.flexboxB {
  display: flex;
  flex-wrap: wrap;
  border: 1px solid #ddd;
  padding: 0.4em;
  margin: 0 0 2em;
}

.flexboxB > div {
  background: #9d9d9d;
  padding: 10px 13px;
  flex: 1 0 200px;
  margin: 0.4em;
  border-radius: 10px;
  flex-basis: 130px;
}
.flexboxB > div:hover{
	background-color: #5d5d5d;
}
.flexboxB a{
	color:#ffffff;
	text-decoration: none;
	display: block;
	}

.flexboxC {
  display: flex;
  flex-wrap: wrap;
  border: 1px solid #ddd;
  padding: 0.4em;
  margin: 0 0 2em;
}

.flexboxC > div {
  background: #5d5d5d;
  padding: 10px 13px;
  flex: 1 0 300px;
  margin: 0.4em;
  border-radius: 10px;
}
.flexboxC > div:hover{
	background-color: #333;
}
.flexboxC a{
	color:#ffffff;
	text-decoration: none;
    display: block;
	}
<!-- //CSS Grid -->