#main-ui {
    width: 80%;
    border: solid 4px black;
    border-radius: 7px;
    background-color: rgba(255, 255, 255, 0.6);
    text-align: center;
    margin: 50px auto;
    padding: 10px 20px;
}

body {
    font-family:'Open Sans', 'Helvetica Neue', sans-serif;
    font-weight: bold;
    background-image: url("./abacus.jpg");
    background-size: cover;
    height: 90vh;
}

h1 {
    margin-top: 10px;
    margin-bottom: 10px;
}

h2 {
    font-size: 50px;
    margin-top: 0;
    margin-bottom: 20px;
}

#keypad {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-evenly;
    padding-top: 10px;
}

button {
    border: solid 2px black;
    border-radius: 5px;
    padding: 5px;
    font-weight: bold;
    color: white;
    width: 200px;
    margin-bottom: 5px;
}

#increment-btn {
    background-color: #1b943b;
}

#decrement-btn {
    background-color: #94271b;
}

#save-btn {
    background-color: #1b5594;
}

#reset-btn {
    background-color: #90941b;
}

.reference {
    display: inline;
    background-color: white;
    padding: 5px;
    border: 1px solid black;
    border-radius: 3px;
    font-size: 12px
}