*,
*::before,
*::after {
    box-sizing: border-box;
    font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande',
        'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
    font-weight: 600;
}

:root {
    --main-lightgray: rgb(221, 221, 221);
    /* --main-gray:rgb(201, 199, 199); */
    --main-gray: rgb(188, 188, 188);
    --main-darkgray: rgb(127, 127, 127);
    --main-orange: rgb(204, 102, 1);
    --main-black: #1c1c1c;
    --main-white: #f5f6f7;

    --main-lightgray-hover: rgb(221, 221, 221, 0.6);
    --main-gray-hover: rgb(201, 199, 199, 0.8);
    --main-gray-hover: rgb(188, 188, 188, 0.8);
    --main-darkgray-hover: rgb(127, 127, 127, 0.8);
    --main-orange-hover: rgb(204, 102, 1, 0.85);
    --main-black-semitransparent: rgb(28, 28, 28, 0.95);
}

body {
    padding: 0;
    margin: 0;
    background-color: var(--main-white);
}

.calculator-grid {
    display: grid;
    justify-content: center;
    align-content: center;
    min-height: 100vh;
    grid-template-columns: repeat(4, 80px);
    grid-template-rows: minmax(120px, auto) repeat(5, 70px);
}

.calculator-grid > button {
    font-size: 2em;
    cursor: pointer;
    border: 1px solid var(--main-white);
    outline: none;
}

.calculator-grid button:nth-child(17){
border-radius: 0 0 0 20px;
}

.button-ac,
.button-del {
    background-color: var(--main-gray);
}

.button-ac:hover,
.button-del:hover {
    background-color: var(--main-gray-hover);
}

.button-operator {
    background-color: var(--main-orange);
}

.button-operator:hover {
    background-color: var(--main-orange-hover);
}

.button-numeric {
    background-color: var(--main-lightgray);
}

.button-numeric:hover {
    background-color: var(--main-lightgray-hover);
}

.button-equal {
    background-color: var(--main-gray);
    border-radius:0 0 20px 0;
}

.button-equal:hover {
    background-color: var(--main-gray-hover);
}

.span-two {
    grid-column: span 2;
}

.output {
    border-radius:20px 20px 0 0;
    grid-column: 1 /-1;
    background-color: var(--main-black-semitransparent);
    padding: 0 10px;

    display: flex;
    align-items: flex-end;
    flex-direction: column;
    justify-content: space-around;

    word-wrap: break-word;
    word-break: break-all;
}

.previous-operand {
    color: var(--main-lightgray-hover);
    font-size: 1.3rem;
}

.current-operand {
    color: var(--main-white);
    font-size: 2rem;
}