:root {
  --selected-color: #c6d7d2;
  font-family: Arial, Helvetica, sans-serif;
}

* {
  box-sizing: border-box;
}

html, body {
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
  position: relative;
}

main {
  width: 600px;
  height: 600px;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  filter: drop-shadow(0 0 5px #000);
  box-shadow: 0 0 15px rgb(0 0 0 / 12%), 0 0 30px rgb(0 0 0 / 5%);
}

.row {
  display: flex;
  flex-direction: row;
}

.box {
  width: 200px;
  height: 200px;
  cursor: pointer;
} .box:hover {
  border: 1px solid rgba(0, 0, 0, 0.2);
}

.wrapper {
  width: 600px;
  margin: 0 auto;
  position: relative;
} .wrapper:hover>button {
  opacity: 1;
} .wrapper:hover>h1 {
  opacity: 0;
}


.wrapper>button {
  opacity: 0;
  z-index: 2;
  width: 100%;
  background-color: #000;
  color: #fff;
  border-top-left-radius: 10px;
  border-top-right-radius: 10px;
  transition: opacity 200ms;
  border: none;
  cursor: pointer;
  font: inherit;
  font-size: 32px;
  font-weight: 700;
  position: absolute;
  padding: 0;
  padding-block: 0.67em;
}

h1 {
  opacity: 1;
  transition: opacity 200ms;
  margin: 0;
  padding-block: 0.67em;
  text-align: center;
}