teachers.css

*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family: "Josefin Sans",sans-serif;
}

body{    
   
    background-image: url(https://wallpaperaccess.com/full/934072.jpg);
    
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-size: 100% 100%;
}

nav{
    display: flex;
    justify-content: space-around;
    padding-top: 15px;
}

a{
    text-decoration: none;
    color: whitesmoke;
}

.topnav ul{
    display: flex;
    padding: 0 15px;
}
.topnav ul li{
    list-style: none;
    padding: 5px 15px;
}

.topnav a:hover{
    /*background-color: gold;*/
    color: aqua;
    border-bottom: 5px solid #fbb73c;
}

.center{
    position: absolute;
    display: grid;

    top:40%;
    left: 15%;
}

.text::after{
    content: "";
    animation: changetext 9s infinite linear ;
    color: ivory;
    font-size: 30px;
    /*display: grid;
    place-items: center;
    margin-top:250px ;*/
    font-weight: 700;
}

@keyframes changetext{
    0%{content: "Online Classes ? ";}
    40%{content:"Staring at the screen All day ";}
    70%{content: "Seeing 100 videos for us  ";}
    90%{content: "Teachers to the Rescue";}
    100%{content: "Thanks a lot ";}
}


.copyright {
    font-size: 13pt;
    bottom:0px;
    text-align:right;
    font-weight: 600;
    position: absolute;
    padding-bottom: 3px;
    right:0px; 
    color: black;
}
.contacts img {
    height: 35px;
    width: 35px;
    margin-left: 7px;
    margin-right: 7px;
    
}
.contacts a {
    text-decoration: none;
}
.contacts img:hover {
    opacity: 0.8;
}
.contacts{
    text-align: right;
    bottom:0px;
    position: absolute;
    padding-bottom: 3px;
}


.respons{
    width:100%;
    height:0;
    padding-bottom:56.25%;
    position:relative;
    margin-left:14%;
        
}

.respons iframe{
    position:absolute;
    width:70%;
    height:70%
}

.responsive{
    width:100%;
    height:0;
    padding-bottom:56.25%;
    position:relative;
        
}

.responsive iframe{
    position:absolute;
    width:75%;
    height:70%
}