* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Popins', sans-serif;
}

html {
    height: 100%;
}

body {
    background: radial-gradient(ellipse at top, #94caff, transparent), radial-gradient(ellipse at bottom, #94e5ff, transparent);
    display: flex;
    align-items: center;
    flex-direction: column;
}

body.dark-mode {
    background: radial-gradient(ellipse at top, #009aff, #000), radial-gradient(ellipse at bottom, #000026, #000);
}

#calculator {
    position: absolute;
    top: 50%;
    left: 50%;
    -ms-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
    width: 350px;
    box-shadow: 0px 0px 6px 3px #000;
}

#calculator.dark-mode {
    box-shadow: 0px 0px 6px 3px #fff;
}

#screen.dark-mode {
    background-color: #1e1e1e;
    color: #ffffff;
}

#screen {
    width: 100%;
    height: 120px;
    background-color: #fff;
    color: #000;
    padding: 8% 10px;
    align-items: center;
    position: relative;
    text-align: right;
    overflow: hidden;
}

.display {
    opacity: 0.6;
    font-size: 20px;
    margin-bottom: 5px;
}

.display2 {
    font-size: 32px;
}

.button_wrapper {
    display: flex;
    flex-wrap: wrap;
}

.buttons {
    height: 80px;
    width: 25%;
    background-color: #191919;
    color: #ffffff;
    font-size: 22px;
    outline: none;
    border: 1px solid #000000;
    cursor: pointer;
    transition: 0.2s;
    justify-content: center;
    align-items: center;
    display: flex;
}

.buttons.dark-mode {
    background-color: #d3d3d3;
    color: #191919;
}

.buttons:hover {
    background: #323232;
}

.buttons.dark-mode:hover {
    background: #fff;
}

.change-theme {
    margin-top: 1rem;
    border-radius: 1em;
    padding: 0.25rem;
}

div.zero {
    width: 50%;
}

@media only screen and (max-width: 600px) {
    .buttons:hover {
        background: #191919;
    }
}