*{margin: 0;padding: 0;font-family: Arial, Helvetica, sans-serif ;}

header{background-image:linear-gradient(rgba(0,0,0,0.5),rgba(0,0,0,0.5)) , url(gettyimages-1354937085.jpg);height: 100vh;background-size: cover;background-position: center;
}


ul{list-style-type: none;
float: right;}
ul li{display:inline-block ; margin-top:25px ;padding: 10px;}
ul li a{text-decoration: none; color: white;
padding: 10px 30px; border: 1px solid transparent;}
ul li a:hover{background-color: white;color: black;
transition: 0.6s ease;}
.main{max-width: 1200px ;
margin: auto;}
ul li.active a{background-color: white;color: black;}
.title{position: absolute;
top: 45%;
left: 50%;
transform: translate(-50% ,-50%);}

.title h1{color: antiquewhite; font-size: 50px;text-align: center;margin-bottom: 20px;}
.title p{color: white; font-size: 20px;text-align: center;}
 table,tr,td{border: 1px solid rgba(0, 0, 0, 0.397);border-collapse: collapse;min-height: 6cm;min-width: 3cm;padding: 20px; background-color: rgba(248, 248, 255, 0.212);}
 .t1{margin-top: 1cm;margin-left: 1cm;position: absolute; top: 35%;}
 button{padding: 15px 25px;background-color: rgb(44, 65, 131);color: white;font-size: 20px;}
 button:hover{ 
    box-shadow: 0px 0px 20px black, 0px 0px 10px white;
    transform: scale(1.1);
 }

 main{background-size: cover;background-position: center;display: flex;flex-direction: column;align-items: center;}

 body{background-image: linear-gradient(rgba(0,0,0,0.5),rgba(0,0,0,0.5)) , url(https://i2-prod.mirror.co.uk/incoming/article20894369.ece/ALTERNATES/s1200c/2_Asteroid-reaches-the-earth.jpg);background-size: cover;background-position: top;}