* {
    margin: 0;
    padding: 0;
    font-family: sans-serif;
}
.hero {
    width: 100%;
    height: 100vh;
    background-image: url(images/background2.png);
    background-size: cover;
    background-position: center;
    position: relative;
    overflow: hidden;
    z-index: -1;
}
.logo {
    width: 120px;
    cursor: pointer;
}
.navbar {
    width: 85%;
    height: 15%;
    margin: auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
button {
    color: #fbfcfd;
    padding: 10px 25px;
    background: transparent;
    border: 1px solid #fff;
    border-radius: 20px;
    outline: none;
    cursor: pointer;
}
.content {
    color: #fbfcfd;
    position: absolute;
    top: 50%;
    left: 8%;
    transform: translateY(-50%);
    z-index: 2;
}
h1 {
    font-size: 80px;
    margin: 10px 0 30px;
    line-height: 80px;
}

.sidebar {
    width: 50px;
    height: 100vh;
    background: linear-gradient(#137DE5, #32B3F7);
    position: absolute;
    right: 0;
    top: 0;
}
.menu {
    display: block;
    width: 25px;
    margin: 40px auto 0;
    cursor: pointer;
}
.social-links img, .useful-links img {
    width: 25px;
    margin: 5px auto;
    cursor: pointer;
}
.social-links {
    width: 50px;
    text-align: center;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
}
.useful-links {
    width: 50px;
    text-align: center;
    position: absolute;
    bottom: 30px;
}

                              /*  Bubbles  */
.bubbles img {
    width: 50px;
    animation: bubble 7s linear infinite;
}
.bubbles {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-around;
    position: absolute;
    bottom: -70px;
}
@keyframes bubble {
    0% {
        transform: translateY(0);
        opacity: 0;
    }
    50% {
        opacity: 1;
    }
    70% {
        opacity: 1;
    }
    100% {
        transform: translateY(-80vh);
        opacity: 0;
    }
}


.bubbles img:nth-child(1) {
    animation-delay: 2s;
    width: 25px;
}
.bubbles img:nth-child(2) {
    animation-delay: 1s;
}
.bubbles img:nth-child(3) {
    animation-delay: 3s;
    width: 25px;
}
.bubbles img:nth-child(4) {
    animation-delay: 4.5s;
}
.bubbles img:nth-child(5) {
    animation-delay: 3s;
}
.bubbles img:nth-child(6) {
    animation-delay: 6s;
    width: 28px;
}
.bubbles img:nth-child(7) {
    animation-delay: 7s;
    width: 35px;
}

@media screen and (max-width: 600px) {
    h1 {
        font-size: 36px;
        line-height: 50px;
    }
    .sidebar {
        width: 100%;
        height: 50px;
        top: auto;
        bottom: 0;
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: 0 10px;
        box-sizing: border-box;
    }
    .social-links {
        width: auto;
        position: unset;
        transform: none;
    }
    .useful-links {
        width: auto;
        position: unset;
    }
    .menu {
        width: 18px;
        margin: 0;
        cursor: pointer;
    }
    .hero {
        background-image: url(images/back-small.png);
    }
}

@media screen and (max-width: 900px) and (min-width: 600px) {
    h1 {
        font-size: 45px;
        line-height: 50px;
    }
    
}