*{
    box-sizing: border-box;
    padding: 0;
    margin:0 ;
}
html{
    background: linear-gradient(#fff,#000)  ;
    
}
h1{
    text-align: center;
    font-size: 3rem;
    margin: .6rem 0;       
    font-family:sans-serif ;
    text-shadow: rgb(31, 31, 31) 6px 5px 6px; 
}
#tab{
    margin: .6rem auto;
}
#tab1{
    margin: 1rem auto;
    text-align: center;
    color: red;
}

input[type="text"]{
    background-color: #fff;
    height: 3rem;
    width: 3rem;
    text-align: center;
    font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
    font-size: 24px;
    margin: 2px;
}
.btn-container{
    text-align: center;
}
.btn{
    height: 2rem;
    margin: 0.2rem 0.3rem 1rem 0.3rem;
    padding: 0.2rem 0.3rem 0.1rem 0.3rem;
    border-radius: 5px;
    background-color: #1554a7;
    color: #fff;
    font-size: 1.2rem;
    font-weight: bold;
}