*, *::before, *::after {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family: Impact, Haettenschweiler, 'Arial Narrow Bold', sans-serif;
}
body {
    background: linear-gradient(to right, #c3ebff, rgb(0, 120, 185));
}
/* digital clock */
.clock-container {
    width: 400px;
    height: 100px;
    background-color: rgba(0, 0, 0, .75);
    border: 1px solid black;
    color: rgba(255, 255, 255, .9);
    text-align: center;
    margin: 20px auto;
}
#current-date {
    padding-top: 10px;
    font-size: 1.2rem;
    text-align: center;
    color: rgba(255, 255, 255, .9)

}
#clock {
    color: rgba(255, 255, 255, .9);
    font-size: 50px;
    text-align: center;   
}
/* calculator */
.calculator-grid {
    display: grid;
    justify-content: center;
    align-content: center;
    min-height: 80vh;
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}
.calculator-grid > button {
    cursor: pointer;
    font-size: 2rem;
    border: 1px solid black;
    outline: none;
    background-color: rgba(255, 255, 255, .75);
}
.calculator-grid > button:hover {
    background-color: rgba(255, 255, 255, .9);
}  
.span-two {
    grid-column: span 2;
}  
.output {
    grid-column: 1 / -1;
    background-color: rgba(0, 0, 0, .75);
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    flex-direction: column;
    padding: 10px;
    word-wrap: break-word;
    word-break: break-all;
}  
.output .previous-operand {
    color: rgba(255, 255, 255, .75);
    font-size: 1.5rem;
} 
.output .current-operand {
    color: white;
    font-size: 2.5rem;
}

@media screen and (max-width: 600px) {
    body {
        background: linear-gradient(to right, #62cbff, rgb(0, 66, 102));
    }
    #clock {
        width: 200px;
        padding: 5px;
        font-size: 50px;
    }
    .calculator-grid {
        margin-top: 50px;
        min-height: 60vh;
        grid-template-columns: repeat(4, 80px);
        grid-template-rows: minmax(100px, auto) repeat(5, 80px);
    }
    .calculator-grid > button {
        cursor: pointer;
        font-size: 1.5rem;
    } 
    .output .current-operand {
        font-size: 2.0rem;
    }

  }