* {
  box-sizing: border-box;
}

.pointer {
    cursor:pointer;
}

.flex-container {
  display: flex;
  flex-direction: row;
  text-align: center;
  border: 0px solid #ffffff;
}

.flex-item-left {
  padding: 10px;
  flex: 50%;
}

.flex-item-right {
  padding: 10px;
  flex: 50%;
}

/* Responsive layout - makes a one column-layout instead of two-column layout */
@media (max-width: 800px) {
.flex-container {
  flex-direction: column;
  }
}

.text{
color: white;
text-align: center;
font-size: 15px;
}

body {
  background-image: linear-gradient(to left, #8360c3, #2ebf91);
 }

button {
background-color: rgb(0, 0, 0);
border-radius: 6px;
border: none;
color: rgb(255, 255, 255);
padding: 10px;
text-transform: uppercase;
font-weight: bold;
width: 200px;
cursor: pointer;
}
#placeholder {
background-color: rgb(255, 255, 255);
height: 200px;
width: 200px;
padding: 50px;
margin: 50px auto;
border: 4px solid black;
border-radius: 25px;
font-size:100px;
color: rgb(255, 0, 0);
line-height: 1.0;
cursor:pointer;
}

<!--#placeholder-button {
background-color: rgb(255, 255, 255);
height: 100px;
width: 100px;
padding: 50px;
margin: 50px auto;
border: 4px solid black;
border-radius: 25px;
font-size:100px;
color: rgb(255, 0, 0);
}-->