html {
    background: #606c88; /* fallback for old browsers */
    background: -webkit-linear-gradient(to right, #606c88, #3f4c6b); /* Chrome 10-25, Safari 5.1-6 */
    background: linear-gradient(to right, #606c88, #3f4c6b); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
    text-align: center;
    font-family: 'Nunito Sans', sans-serif;
}

.calc-frame {
    margin-top: 50px;
    background-color: rgb(207, 220, 228);
    display: inline-block;
    padding: 50px 30px;
    border-radius: 15px;
    box-shadow: 0 0 6px 3px rgba(0, 0, 0, 0.7), inset 0 0px 6px 3px rgba(0, 0, 0, 0.7), inset 0 -10px  rgba(0, 0, 0, 0.3);
}

.calc-buttons {
    display: grid;
    grid-template-columns: repeat(4,60px);
    grid-template-rows: repeat(5,50px);
    grid-gap: 20px;

}

.button {
    color: white;
    background-color: rgb(50, 48, 63);
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 7px;
    font-size: 25px;
    box-shadow: 0 4px 0 rgb(22, 20, 32), 0 0 3px rgba(0, 0, 0, 0.7), inset 0 5px 8px rgba(255, 255, 255, 0.2);
}

.button:active {
    box-shadow: inset 0 3px 8px rgba(255, 255, 255, 0.2);
    transform: translateY(4px);
}

.screen {
    border: 0px solid grey;
    margin-bottom: 40px;
    height: 90px;
    border-radius: 8px;
    background-color: rgb(131, 168, 173);
    box-shadow: inset 0 4px 1px rgba(0, 0, 0, 0.2), inset 0 -4px 3px rgba(0, 0, 0, 0.2);
    display: flex;
    justify-content: flex-end;
    align-items: center;
    font-size: 35px;
}

.screen-text {
    margin: 0 20px;
}

.btn16 {
    grid-row-start: 4;
    grid-row-end: span 2;
    grid-column: 4;
}

.sig {
    margin-top: 10px;
    color: white;
}

a {
    color: rgb(113, 189, 189);
    text-decoration: none;
}