*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family:sans-serif;
}
body{
    width: 100%;
    height: 100vh;
    background-color: rgb(240, 240, 240);
    display: flex;
    justify-content: center;
    align-items: center;
}
.app{
    display: grid;
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: minmax(200px, auto) repeat(5, 100px);
    box-shadow: 5px 5px 10px rgba(0, 0, 0, 0.1);
    
}
.app > button{
    color: #78909c;
    cursor:pointer;
    font-size: 2rem;
    border: 1px solid rgb(240, 240, 240);
    outline: none;
    background-color: white;
}
.app .operation{
    background-color: rgb(240, 240, 240);
    border: 1px solid white;
    font-weight: 500;
}

.app .equal{
    background-color: rgb(255, 100 , 100);
    border:none;
    color: white;
}
.app>button:hover{
    transform: scale(1.1);
    transition: all .4s;
}
.output{
    grid-column: 1 / -1;
    background-color: #78909c;
    display: flex;
    align-items: flex-end;
    flex-direction: column;
    padding: 10px;
    word-wrap: break-word;
    word-break: break-all;
}
.output .previous-operand{
    color: rgba(255, 255, 255, 0.75);
    font-size: 1.5rem;
    margin-top: auto;
    padding: 10px;
}
.output .current-operand{
    min-height: 67px;
    color: rgba(255, 255, 255, 1);
    font-size: 2.5rem;
    font-weight: bold;
    padding: 10px;
}