sheet1.css

body
{ 
    height: 100%;
    width: 100%;
    position: relative;
}
#header {
    width: 100%;

    margin-left: 35%;

}

#grid {
    width: 10%;
    height: 10%;

    margin-left: 30%;
    margin-top: 0;

    border: 3px solid #000000;
}

#sudoku {
    margin: 10%;
}

.cell input {
    display: inline-block;

    border: 1% solid black;
    width: 40px;
    height: 40px;

    text-align: center;
    font-size: 30px;
}
.cell1 input {
    display: inline-block;

    border: 1% solid black;
    width: 40px;
    height: 40px;

    text-align: center;
    font-size: 30px;
}
.cell1
{
    border-width: 4px;
    border-color:blue;
}
.cell
{
    border-width: 4px;
    border-color: red;
}
nav
{
    list-style-type: none;
    background-color: #333333;
    overflow: hidden;
    margin-left: 40%;
    padding: 0;
    width: 30%;
    margin-top: 5%;
    


}
li
{
    list-style: none;
    float:left;
}

a
{
    text-decoration: none;
    color: white;
    display: block;
    text-align: center;
    padding: 10px;
}
a:hover
{
        background-color: #111111;
}
.button
{
    float: right;
    background-color: #008CBA; 
    border: none;
    color: white;
    padding: 10px 25px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 25px;
    margin: 4px 2px;
    cursor: pointer;
    border-radius: 12px;        
}