html,
body {
    margin: 0;
    width: 100%;
    height: 100%;
    background: #000;
    overflow: hidden;
}

.stage {
    position: fixed;
    inset: 0;

    width: 100vw;
    height: 100vh;

    display: flex;
    justify-content: center;
    align-items: center;
}

.poster {
    position: relative;
    display: block;

    max-width: 100vw;
    max-height: 100vh;
}

.poster img {
    display: block;

    width: auto;
    height: auto;

    max-width: 100vw;
    max-height: 100vh;
}


/* =========================
   لینک‌ها
   ========================= */

.btn {
    position: absolute;
    display: block;

    left: 5.2%;
    width: 12.2%;
    height: 3.8%;
}

.b1 {
    top: 79.1%;
}

.b2 {
    top: 84.5%;
}

.b3 {
    top: 89.9%;
}


/* =========================
   فقط موبایل
   ========================= */

@media screen and (max-width: 767px) {

    .stage {
        display: block;
    }

    .poster {
        position: absolute;

        left: 50%;
        top: calc(50% - 30px);

        transform: translate(-50%, -50%);

        width: 100vw;
        max-width: 100vw;
        max-height: none;
    }

    .poster img {
        width: 100%;
        height: auto;

        max-width: none;
        max-height: none;
    }

}