body {
  font-family: sans-serif;
  margin: 0;
  padding: 20px;
  font-size: x-large;
}

button, select, input {
  font-size: inherit; /* body のフォントサイズを継承 */
}

h1 {
  text-align: center;
}

#user-form,
#match-form,
#user-list {
  margin-bottom: 20px;
  padding: 10px;
  border: 1px solid #ccc;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  padding: 8px;
  text-align: left;
  border-bottom: 1px solid #ddd;
}

@media (max-width: 600px) {
  table {
    display: block;
    overflow-x: auto;
  }

  th, td {
    display: block;
    width: 100%;
    box-sizing: border-box;
  }

  thead {
    display: none;
  }

  tr {
    margin-bottom: 10px;
    display: block;
  }

  body {
    font-size: 36px;
  }

  th, td {
    padding: 24px;
    font-size: 28px;
  }

  input[type="text"],
  select,
  button {
    font-size: 36px;
    padding: 24px;
    margin-bottom: 20px;
  }

  h1 {
    font-size: 48px;
  }
}