h1 {
    text-align: center;
    font-size: 60px;
    margin: 0;
    padding: 20px 0;
    border: 5px solid black;
    background-color: #00ffff;
    text-shadow: 3px 3px 1px black;
    }
body{
    width: 600px;
    margin: 0 auto;
    background-color: #ffffff;
    padding: 0 20px 20px 20px;
    border: 5px solid black;
    font-weight: bold;
}
p{
    text-align: left;
    font-size: 16px;
    line-height: 1;
    letter-spacing: 0px;
    width: 400px;
    margin: 0 auto;
    background-color: #ffffff;
    padding: 0 10px 10px 10px;
    border: 5px solid black;
}
li, ul{
    text-align: left;
    font-size: 16px;
    line-height: 1;
    letter-spacing: 0px;
}
html{
    /*px=> "pixels"; the height is
    14 pixels for the base font size.*/
    /*background-color: hwb(41 72% 6%);*/
    /*background-image: url("images/black-sky-blue-atmosphere-astronomical-object-purple-1562859-pxhere.com.jpg");*/
    /*change to a space background?*/
    background-image: url("https://c.pxhere.com/photos/ee/c5/astronomy_dark_evening_galaxy_nature_night_night_sky_outdoors-1562859.jpg!d");
    /*<img src="https://c.pxhere.com/photos/ee/c5/astronomy_dark_evening_galaxy_nature_night_night_sky_outdoors-1562859.jpg!d"
    srcset="https://c.pxhere.com/photos/ee/c5/astronomy_dark_evening_galaxy_nature_night_night_sky_outdoors-1562859.jpg!d"
    alt="黑色, 天空, 蓝色, 大气层, 天文物体, 紫色, 星, 星座, 晚, 空间, 电蓝色, 外太空, 黑暗, 宇宙, 天文学, 星系, 午夜, 银河, 天体事件, 科学, 图片素材 In PxHere">*/
    /*<p>Photo by <strong><a href="https://pxhere.com/zh/photographer/1163407?utm_content=clipUser&utm_medium=referral&utm_source=pxhere">FelixMittermeier</a></strong>
    from <strong><a href="https://pxhere.com/zh/photo/1562859?utm_content=clipUser&utm_medium=referral&utm_source=pxhere">PxHere</a></strong></p>*/
    /*https://pxhere.com/zh/photo/1562859?utm_content=shareClip&utm_medium=referral&utm_source=pxhere*/
}
img{
    display: block;
    margin: 0 auto;
    border: 3px solid black;
}
.textbox{
    display: block;
    background-color: hwb(41 72% 6%);
    padding: 0 10px 10px 10px;
    border: 5px solid black;
}
span{
    display: inline-block;
    font-weight: bolder;
}
.headlink{
    text-align: center;
    font-size: 20px;
    line-height: 1;
    letter-spacing: 0;
    margin: 0 auto;
    background-color: hwb(41 72% 6%);
    padding: 0 10px 10px 10px;
    border: 5px solid black;
    display: inline-block;
    font-weight: bolder;
}
.highlightthisaqua{
    background-color: #00ffff;
}
#page1{
    display: inline-block;
}
#page2{
    display: inline-block;
}