mainpage.css

* {
    margin: 0;
    padding: 0;
}

body {
    overflow-x: hidden;
}

.header {
    min-height: 100vh;
    width: 100%;
    background-image: linear-gradient(rgba(4, 9, 30, 0.7), rgba(4, 9, 30, 0.7)), url("bgimg.jpg");
    background-position: center;
    background-size: cover;
    /* position: relative;*/
}

nav {
    display: flex;
    padding: 2% 6%;
    justify-content: space-between;
    align-items: center;
}

nav img {
    height: 10vh;
    width: 30%;
}

.navlist {
    flex: 1px;
    text-align: right;
    font-family: 'Oswald', sans-serif;
}

.navlist ul h1 {
    color: coral;
    font-family: 'Times New Roman', Times, serif;
    padding: 8px 12px;
}

.navlist ul li {
    list-style: none;
    display: inline-block;
    padding: 8px 12px;
    position: relative;
}

.navlist ul li a {
    color: white;
    text-decoration: none;
    font-size: 15px;
}

.navlist ul li::after {
    content: '';
    width: 0%;
    height: 2px;
    background: #f44336;
    display: block;
    margin: auto;
    transition: 0.5s;
}

.navlist ul li:hover::after {
    width: 100%;
}

.text_box {
    width: 90%;
    color: white;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.text_box h1 {
    font-size: 62px;
}

.text_box p {
    margin: 10px 0 40px;
    font-size: 14px;
    color: white;
}

.hero-btn {
    display: inline-block;
    text-decoration: none;
    color: tomato;
    border: 1px solid white;
    padding: 13px 34px;
    font-size: 15px;
    background: transparent;
    position: relative;
    cursor: pointer;
}

.hero-btn:hover {
    border: 1px solid tomato;
    color: white;
    background: tomato;
    transition: 1s;
}

nav .fa {
    display: none;
}

@media(max-width: 700px) {
    .text_box h1 {
        font-size: 20px;
    }
    .navlist ul li {
        display: block;
    }
    .navlist {
        position: fixed;
        background: tomato;
        height: 100vh;
        width: 200px;
        top: 0;
        right: -200px;
        text-align: left;
        z-index: 2;
        transition: 1s;
    }
    .navlist ul h1 {
        color: white;
        font-family: 'Times New Roman', Times, serif;
        text-align: center;
        padding-top: 10px;
        padding-bottom: 20px;
    }
    nav .fa {
        display: block;
        color: white;
        margin: 10px;
        font-size: 22px;
        cursor: pointer;
    }
    .navlist ul {
        padding: 30px;
    }
    nav img {
        height: 10vh;
        width: 50%;
    }
}


/*------------About US-------------*/

.aboutUs {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #161623;
    position: relative;
}

.aboutUs::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(#f00, #f0f);
    clip-path: circle(45% at right 70%);
}

.aboutUs::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(#2196f3, #e91e63);
    clip-path: circle(30% at 10% 10%);
}

.container {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    max-width: 1200px;
    flex-wrap: wrap;
    z-index: 1;
}

.container .card {
    position: relative;
    width: 280px;
    height: 400px;
    margin: 30px;
    box-shadow: 20px 20px 50px rgba(0, 0, 0, 0.5);
    border-radius: 15px;
    background: rgba(255, 255, 255, 0.1);
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    border-top: 1px solid rgba(255, 255, 255, 0.5);
    border-left: 1px solid rgba(255, 255, 255, 0.5);
    backdrop-filter: blur(5px);
}

.container .card .content {
    padding: 18px;
    text-align: center;
    transform: translateY(100px);
    opacity: 0.2;
    transition: 0.5s;
}

.container .card:hover .content {
    transform: translateY(0px);
    opacity: 1;
}

.container .card .content h1 {
    position: relative;
    font-size: 3em;
    color: tomato;
    z-index: 1;
}

.container .card .content p {
    font-size: 1em;
    color: white;
    font-weight: 300;
}