Untitled-1.css

* {
    margin: 0 auto;
    padding: 0;
}

.header {
    width: 1200px;
    height: 1000px;
}
.nav ul {
    list-style-type:none;
}
.nav ul li {
     width: 170px;
     height: 50px;
     /*float:left;*/
     background-color: pink;
     display: inline-block;   /* what is inline block doing? */ 
     cursor:pointer;
}
.nav a:hover{
    color:green;
    background-color: yellow;
    text-decoration:underline ;
    display: inline-block;

     
}
/* Formatting DropDown -------------------------------- */
.drop {
    width: 1200px;
    height: 40px;
    background: linear-gradient(orange, yellow);
}

.drop ul {
    list-style-type: none;
}

.drop a {
    width: 240px;
    height: 40px;
    background: linear-gradient(rgb(245, 245, 245), blue);
    color: white;
    float: left;
    text-align: center;
    line-height: 40px;
}

.drop ul li ul {
    display: none;
}

.drop ul li:hover ul {
    display: block;
}

.drop ul li {
    width: 240px;
    height: 40px;
    float: left;
}

/* for formatting of nav------------------ */

.drop ul li a:hover {
    background: linear-gradient(red, yellow);
}

.drop>ul>li>ul>li>a:hover {
    background: linear-gradient(black, gray);
}
/* Formatting registration form ---------------------------------- */
.first {
    width: 1200px;
    height: 500px;
    background-image: url("10.jpg");
}

.second {
    width: 500px;
    height: 400px;
    /*background-color:orange;*/
    background-color: rgba(0, 0, 0, 0.1);
    font-size: 30px;
    font-weight: bold;
    text-decoration: underline;
    font-style: italic;
    font-family: arial black;
    text-decoration-color: red;
    text-decoration-style: dotted;
    letter-spacing: 10px;
    word-spacing: 20px;
    /*opacity:0.1;*/
}

.third {
    width: 800px;
    height: 500px;
    background: linear-gradient(rgba(255, 0, 0, 0.4), rgba(0, 255, 0, 0.5), blue);
    padding-top: 150px;
    box-sizing: border-box;
}


.third ul {
    list-style-type: none;
}

.third input {
    padding: 5px;
    margin-top: 5px;
    font-size: 20px;
    background-color: transparent;
    color: white;
    /*border:none;*/
    /*border:1px solid gray;*/
    border: none;
    border-bottom: 1px solid gray;

}

.third form {
    background-color: rgba(0, 0, 0, 0.5);
    width: 300px;
    padding: 10px;

}