body {
    padding: 0;
    margin: 0;
    font-family: verdana;
    background-color: black;
}
  
.container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 100%;
    height: 100vh;
    background-color: black;
}
  
h1 {
    color: white;
    text-align: center;
    background-color: black;
    font-size: 40px;

}

h2 {
    color: white;
    text-align: center;
    background-color: black;
    font-size: 22px;
}

h3 {
    color: white;
    text-align: center;
    background-color: black;
    font-size: 10px;
}


.link { color: #FF0000; } /* CSS link color (red) */
.link:hover { color: #00FF00; } /* CSS link hover (green) */
  
.digit {
    font-size: 50px;
    color: #fff;
}
  
.txt {
    font-size: 20px;
    color: #fff;
    text-align: center;
}

 
#buttons {
    margin-top: 5px;
}

#buttons2 {
    margin-top: 5px;
}
  
.btn {
    width: 70px;
    padding: 5px 5px;
    margin: 0px 5px;
    border-top-right-radius: 0px;
    border-bottom-left-radius: 0px;
    border-bottom-right-radius: 0px;
    border-top-left-radius: 0px;
    cursor: pointer;
    font-size: 15px;
    transition: 0.5s;
    color: white;
    font-weight: 500;
}
  
#start {
    background-color: black;
}
  
#stop {
    background-color: black;
}
  
#reset {
    background-color: black;
}

#plus {
    background-color: black;
}

#minus {
    background-color: black;
}

#minus10 {
    background-color: black;
}