:root {
    --battery-height: 50px;
    --battery-width: calc(var(--battery-height) / 2);

    --charge-triangle-height: 15px;
    --charge-triangle-width: calc(var(--charge-triangle-height) / 2);

    --battery-fill-color: #34a853;

    --animation-duration: 750ms;
}

body,
html {
    height: 100%;
}

body {
    background-color: #222;
}

.container {
    height: 300px;
    width: 300px;
    left: 50%;
    top: 50%;
    position: absolute;
    transform: translate(-50%, -50%);
}

.battery {
    position: relative;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    height: var(--battery-height);
    width: var(--battery-width);
    border-radius: 3px;
    background-color: black;
    overflow: h;
}

.battery::before,
.battery::after {
    content: '';
    left: 50%;
    top: 0%;
    transform: translate(-50%, -99%);
    height: 3px;
    width: 10px;
    position: absolute;
    background-color: black;
}

.battery::after {
    z-index: 1;
    background-color: var(--battery-fill-color);
    animation: fill-top 100ms linear forwards calc(var(--animation-duration) * 0.8);
    transform: scaleY(0) translate(-50%, -99%);
}

@keyframes fill-top {
    from {
        transform: scaleY(0) translate(-50%, -99%);
    }

    to {
        transform: scaleY(1) translate(-50%, -99%);
    }
}

.fill {
    position: absolute;
    z-index: -1;
    background-color: var(--battery-fill-color);
    height: 100%;
    width: 100%;
    top: 0%;
    left: 0%;
    border-radius: 3px;
    animation: charge var(--animation-duration) linear forwards;
    transform-origin: 50% 100%;
}

@keyframes charge {
    0% {
        transform: scaleY(0);
    }

    80%,
    100% {
        transform: scaleY(1);
    }
}

.charge {
    position: relative;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    height: calc(var(--charge-triangle-height) * 1.8);
    width: calc(var(--charge-triangle-width) * 1.5);
}

.triangle {
    clip-path: polygon(100% 0, 0% 100%, 100% 100%);
    background-color: white;
    height: var(--charge-triangle-height);
    width: var(--charge-triangle-width);
    position: absolute;
}

.triangle:nth-of-type(2) {
    transform: rotate(180deg) translateY(-80%) translateX(-50%);
}