body {
    background:
        linear-gradient(150deg, rgba(23, 32, 51, .98), rgba(33, 43, 62, .96)),
        linear-gradient(45deg, rgba(255, 107, 74, .16), rgba(31, 191, 154, .12));
}

header {
    width: var(--all-width);
}

header .logo {
    margin: 0 auto;
}

footer {
    margin: 0 auto;
}

main {
    width: min(1440px, calc(100vw - 32px));
    min-height: calc(100vh - 120px);
    margin: 20px auto 24px;
    display: flex;
    align-items: stretch;
}

.game {
    flex: 1;
    min-height: min(780px, calc(100vh - 150px));
    background-color: #05070d;
    border: 1px solid rgba(255, 255, 255, .12);
    border-radius: 8px;
    box-shadow: 0 26px 70px rgba(0, 0, 0, .36);
    overflow: hidden;
    position: relative;
}

.game::before {
    content: "";
    position: absolute;
    inset: 0;
    pointer-events: none;
    box-shadow: inset 0 0 0 1px rgba(255, 255, 255, .06);
    z-index: 1;
}

.h5game {
    display: block;
    width: 100%;
    height: 100%;
    min-height: min(780px, calc(100vh - 150px));
    background: #000;
}

.back {
    width: var(--button);
    height: var(--button);
    position: fixed;
    right: 14px;
    top: 14px;
    padding: 8px;
    border-radius: 8px;
    background-color: rgba(23, 32, 51, .78);
    z-index: 999;
    display: none;
    box-shadow: 0 12px 28px rgba(0, 0, 0, .28);
}

@media screen and (max-width:769px) {
    header {
        width: calc(100vw - 20px);
        margin-top: 10px;
    }

    main {
        width: calc(100vw - 20px);
        min-height: calc(100vh - 98px);
        margin: 12px auto;
    }

    .game,
    .h5game {
        min-height: calc(100vh - 112px);
    }
}

@media only screen and (max-device-width: 768px) and (orientation: landscape) {
    header,
    footer {
        display: none;
    }

    main {
        width: 100vw;
        min-height: 100vh;
        margin: 0;
    }

    .game,
    .h5game {
        min-height: 100vh;
        border: 0;
        border-radius: 0;
    }

    .back {
        display: block;
    }
}