index.css

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen",
    "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue",
    sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

code {
  font-family: source-code-pro, Menlo, Monaco, Consolas, "Courier New",
    monospace;
}

ul {
  list-style: none;
}

.topics-list,
.quizzes-list {
  display: flex;
  flex-wrap: wrap;
}

.topic,
.quiz {
  width: 200px;
  height: 200px;
  background: gray;
  display: flex;
  justify-content: center;
  align-items: center;
  margin-right: 20px;
  margin-top: 20px;
}

.card {
  width: 500px;
  height: 250px;
  background: gray;
  margin: 20px auto;
  display: flex;
  justify-content: center;
  align-items: center;
}