html {
    box-sizing: border-box;
}

*,
*::before,
*::after {
    box-sizing: inherit;
}

body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.calculator {
    min-height: 690px;
    width: 400px;
    background-color: #1E1E1E;
    display: flex;
    flex-direction: column;
    padding: 5px;
}

.display {
    flex: 1;
    color: #fff;
    display: flex;
    justify-content: flex-end;
    align-items: flex-end;
    margin: 0 0 10px 0;
    font-size: 3em;
}

.keypad {
    flex-wrap: wrap;
    flex: 2.5;
    display: flex;
    justify-content: center;
    gap: 5px;
}

.btn {
    padding: 0;
    flex: 1 1 20%;
    color: #ffffff;
    font-size: 2em;
    display: flex;
    justify-content: center;
    align-items: center;
}

.btn-operator {
    background-color: #FE8A00;
}

.btn-function {
    background-color: #707071;
}

.btn-number {
    background-color: #464647;
}

svg {
    width: 40px;
    height: 40px;
    fill: #fff;
}