html {
    height: 100%;
    margin: 0;
}
    
body {
    height: 100%;
    margin: 0;
    display: flex;
    background: url(background.jpg);
    background-size: cover;
}

.main-form {
    background-color: white;
    width: 500px;
    margin: auto;
    text-align: center;
    box-shadow: 0 0 50px black;
}

.sudoku-table {
    margin: auto;
    border-collapse: collapse;
}

.sudoku-cell {
	border-style: solid;
    border-color: black;
    border-width: 1px 1px 1px 1px;
    padding: 3px;
    text-align: center;
	width: 15px;
	height: 15px;
}

.sudoku-edit-cell {
	border: none;
	text-align: center;
	width: 15px;
	height: 15px;
}