style.css

*{
margin: 0;
padding: 0;
font-family:sans-serif;
}
.banner{
    width: 100%;
    height: 100vh;
    background-image: linear-gradient(rgba(0,0,0,0.75),rgba(0,0,0,0.75)),url(design.jpg);
    background-size: cover;
    background-position: center;
}
.navbar{
    width: 85%;
    margin: auto;
    padding:35px 0;
    display: flex;
    align-items: center;
    justify-content: space-between;

}
.logo{
    width:120px;
    cursor: pointer;
}
.navbar ul li{
    list-style: none;
    display: inline-block;
    margin: 0 20px;
    position:relative;
} 
.navbar ul li a{
   text-decoration: none;
    color:#fff;
    text-transform: uppercase
} 
.navbar ul li::after{
   content:'';
    height: 3px;
    width:0;
    background:#009688; 
    position: absolute;
    left: 0;
    bottom: -10px; 
    transition: 0.5s;
} 
.navbar ul li:hover::after{
    width:100%;  
} 
.dropdown_menu{
    display: none;   
}

.navbar ul li:hover .dropdown_menu{
    display: block;
    position: absolute;
    left:0;
    top: 100%;
    background-color: var(--color-black); 
}
.dropdown_menu ul{
    display:block;
    margin: 10px;   
}
.dropdown_menu ul li{
    width: 150px;
    padding: 10px
}

.content{
    width: 100%;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    text-align: center;
    color: #fff; 
}
.content h1{
    font-size: 70px;
    margin-top: 80px; 
}
.content p{
    margin: 20px auto;
    font-weight: 100;
    line-height: 25px;
}
button{
    width: 200px;
    padding: 15px 0;
    text-align: center;
    margin: 20px 10px;
    border-radius: 25px;
    font-weight: bold;
    border: 2px solid #009688;
    background: transparent;
    color: #fff;
    cursor:pointer;
    position:relative;
    overflow:hidden;
}
span{
    background: #009688;
    height:100%;
    width:0;
    border-radius: 25px;
    position:absolute;
    left:0;
    bottom: 0;
    z-index: -1;
    transition:0.5s;
    
}
button:hover span {
    width: 100%;
}
button:hover{
    border: none;
}