html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    font-family: 'Roboto', sans-serif;
}

body {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(4, 1fr);
    height: 100vh;
    width: 100vw;
}

.cell {
    display: flex;
    align-items: center;
    justify-content: center;
}

.subCell {
    background-color: #f0f0f0;
    padding: 10px;
    text-align: center;
    display: none;
}
  
input {
    padding: 5px;
    margin: 5px;
}

button {
    padding: 5px;
    margin: 5px;
}