body{
    background-color: #2c3e50;
    display:flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
#container{
    color: #d7d7d7;
}
.digit{
    font-size: 150px;
    font-weight: bold;
}
.txt{
    font-size:40px;
    font-weight: bold;
}
#btn-container{
    text-align:center;
    margin-top:40px;
}
.btn{
    padding:7px 25px;
    font-size:15px;
    margin:0px 10px ;
    border: none;
    cursor: pointer;
    color:white;

}
#start{
    background-color: #1abc9c;
}
#stop{
    background-color:#3498db;
}
#reset{
        background-color: #e74c3c;
}