body {
    margin: 0;
    padding: 0;
}

button,
h1 {
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

.sudoku-menu {
    width: 50%;
    text-align: center;
    margin-left: auto;
    margin-right: auto;
}

.sudoku-menu button {
    font-size: 24px;
    margin: 10px;
    padding: 5px;
}

.sudoku-container {
    border: 5px solid #666;
    margin-left: auto;
    margin-right: auto;
}

.sudoku-container td {
    margin: 0;
}

.sudoku-container input {
    width: 40px;
    height: 40px;
    text-align: center;
    font-size: 20px;
    padding: 0;
    border: 1px #ccc solid;
    background: transparent;
}

.sudoku-container .sudoku-input-error {
    background: #ffc9d7;
}

.sudoku-container.valid-matrix {
    border: 5px solid #7edb37;
}

.sudoku-section-one {
    background: #ccc;
}

button {
    border-radius: 10px;
    background-color: black;
    color: white;
}

button:hover {
    transition: 0.5s all ease-in-out;
    background-color: #4169e1;
}