style.css

body{
    font-family:'Roboto Mono', monospace;
    font-size: 16px;
    margin: 0px;
    background:#120546 ;
    color: #fff;
    display: flex;
    justify-content: center;
}
.select-box{
    margin-top: 150px;
    width: 380px;
    position: relative; 

}
.select-option{
    position: relative;
}
.select-option input{
    width: 100%;
    background-color: #fff;
    color: #000;
    border-radius: 7px;
    cursor: pointer;
    font-size: 22px;
    padding: 15px 20px;
    border: 0 !important;
    outline: 0 !important;
}
.select-option:after{
    content: "";
    border-top: 12px solid #000;
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    position: absolute;
    right: 15px;
    top: 50%;
    margin-top: -8px;
    

} 
.content{
    background-color: #fff;
    position: absolute;
    color: #000;
    border-radius: 7px;
    margin-top: 15px;
    width: 100%;
    z-index: 999;
    padding: 20px;
    display: none;
} 
.search input{
    width: 92%;
    font-size: 17px;
    padding: 15px;
    outline: 0;
    border: 1px solid #000;
    border-radius: 5px;

} 
.options{
    margin-top: 10px;
    max-height: 250px;
    overflow-y: auto;
    padding: 0px;
}
.options li{
    padding: 10px 15px;
    font-size: 21px;
    border-radius: 5px;
    cursor: pointer;
    border-bottom: 1px solid gray;
}
 .options li:hover{
    background-color: #f2f2f2;
}
.select-box.active .content {
    display: block;
}
.select-box.active .select-option::after{
    transform: rotate(-180deg);
}