building.css

/* .gateway-arch, .gateway-arch-outside {
    position: absolute;
    width: 300px;
    height: 480px;
    border-radius: 100% 100% 0 0;
}

.gateway-arch {
    left: 300px;
    background: #505050;
}

.gateway-arch::before, .gateway-arch-outside::before {
    content: '';
    position: absolute;
    left: 25px;
    top: 19px;
    width: 250px;
    height: 450px;
    background: #6acffe;
    margin: 0 auto;
    border-radius: 100% 100% 0 0;
}

.gateway-arch .arch-side {
    background: #505050;
}

.arch-side  {
    position: absolute;
    bottom: 0;
    height: 0;
    width: 100px;
    margin: 0 0 10px 0;
    padding: 10px;
    border-bottom: 329px solid #505050;
}

.arch-side::after {
    content: '';
    position: absolute;
    top: -2px;
    width: 42px;
    height: 300px;
    background: #6acffe;
}

.arch-left {
    left: -18px;
    border-left: 50px solid transparent;
    border-right: 25px solid transparent;
    transform: rotate(9deg);
}

.arch-left::after {
    left: 33px;
    transform: rotate(-2deg);
}

.arch-right {
    right: -18px;
    border-left: 25px solid transparent;
    border-right: 50px solid transparent;
    transform: rotate(-9deg);
}

.arch-right::after {
    right: 33px;
    transform: rotate(2deg);
}

.gateway-arch-outside {
    left: 315px;
    background: #222;
}

.gateway-arch-outside .arch-side {
    background: #222;
} */

.building-slide {
    background: #6acffe;
    display: flex;
    justify-content: center;
}

.building {
    position: relative;
    top: 6em;
    z-index: 100;
}

.building-side {
    position: absolute;
    width: 200px;
    height: 400px;
    border-style: solid;
    border-width: 40px 83px 31px;
    border-top-color: transparent;
    border-left-color: transparent;
    border-right-color: #e3a7ff;
    border-bottom-color: transparent;
}

.building-front {
    position: absolute;
    left: 200px;
    width: 0;
    height: 400px;
    border-style: solid;
    border-width: 27px 125px 27px;
    border-top-color: transparent;
    border-left-color: #cf6afe;
    border-right-color: transparent;
    border-bottom-color: transparent;
}

.ground-cover {
    position: relative;
    bottom: -290px;
}

.ground {
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 300px 400px;
}

.ground-1 {
    border-top-color: blanchedalmond;
    border-left-color: transparent;
    border-right-color: transparent;
    border-bottom-color: transparent;
    transform: rotateX(60deg);
}
.ground-2 {
    position: absolute;
    top: -202px;
    border-top-color: transparent;
    border-left-color: transparent;
    border-right-color: transparent;
    border-bottom-color: blanchedalmond;
    transform: rotateX(80deg);
}

.windows-front {
    list-style: none;
    position: relative;
    left: -170px;
    perspective: 16px;
}

.windows-side {
    list-style: none;
    position: relative;
    left: -14px;
    top: -13px;
    perspective: 19px;
}

.window {
    background: #fecf6a;
    width: 115px;
    height: 20px;
    margin: 1em;
}

.window-front {
    transform: rotateY(1deg);
}

.window-side {
    width: 60px;
    transform: rotateY(-3deg);
}

.cloud {
    position: relative;
    top: 80px;
}

.cloud-1 {
    top: 80px;
    left: 10px;
}

.cloud-2 {
    top: 110px;
    left: 500px;
}

.cloud-circle {
    background: #eee;
    border-radius: 100%;
    position: absolute;
}

.cloud-circle-1 {
    width: 80px;
    height: 80px;
}

.cloud-circle-2 {
    width: 100px;
    height: 80px;
    top: -33px;
    left: 53px;
}

.cloud-circle-3 {
    width: 90px;
    height: 90px;
    top: -8px;
    left: 115px;
}

.cloud-circle-4 {
    width: 100px;
    height: 54px;
    top: 39px;
    left: 44px;
}