master.css

body {
  padding-top: 50px;
  padding-right: 300px;
}
.logo {
  padding: 0;
  margin: 0;
  height: 50px;
}
.mynav-right {
  padding: 0;
  margin: 0;
  float: right;
}
.mynav {
  text-align: center;
  background-color: greenyellow;
}
.active-bc {
  background-color: lightseagreen;
}
.my-btn {
  width: 160px;
  margin-left: 20px;
  margin-right: 20px;
}
.mytable {
  text-align: center;
}
.t-header {
  text-align: center;
  background-color: seagreen;
}
tr:nth-child(even) {
  background-color: lightblue;
}
.menu {
  background-color: lightgreen;
  position: fixed;
  float: right;
  width: 300px;
  margin: 0;
  height: 100%;
  top: 0;
  right: 0;
  overflow-x: hidden;
  padding-top: 50px;
  text-align: center;
  z-index: 15;
}
.prev-btn {
  float: right;
}
.next-btn {
  float: left;
}
.out-menu {
  text-align: center;
}
.parent-wrapper {
  text-align: center;
}
.parent {
  margin: auto;
  display: flex;
  flex-wrap: wrap;
}
.child {
  background-color: lightblue;
  text-align: center;
  font-size: 5em;
  flex: 1 0 21%;
  margin: 2%;
  width: 100px;
  height: 200px;
  box-shadow: 0;
  transition: box-shadow 1s;
  position: relative;
  z-index: 10;
}
.child:hover {
  box-shadow: 0 0 0.5em black;
}
.responsive-menu {
  margin-left: 0;
  padding: 0;
  display: none;
  width: 5%;
  float: left;
}
@media (max-width: 1000px) {
  .child {
    flex: 1 0 25%;
  }
}
@media (max-width: 600px) {
  .menu {
    display: none;
    background-color: lightgreen;
    position: none;
    float: left;
    left: 0;
  }
  body {
    padding-right: 0;
  }
  .top-nav-item {
    display: none;
  }
  .responsive-menu {
    display: block;
  }
}