New Elements added to the bottom of the page - html

Question

I'm coding a webpage using CSS and PHP. Whenever I add a new element it's pushed down to the bottom of the page. I thought it was a one time thing only affecting a paragraph so I added negative margins for it (not great practice, I know), but every element I add is getting pushed to the end of the page and I have to scroll to find it.
The paragraph below was the part getting pushed down, the login heading remained at the top, but when I tried adding more text after, it got pushed down as well.
#import url('https://fonts.googleapis.com/css2?family=Urbanist:wght#500&display=swap');
* {
width: 100%;
height: 100%;
}
h1 {
color: white;
font-family: 'Urbanist', sans-serif;
font-size: 30px;
line-height: 0px;
margin-bottom: 0px;
}
p {
color: white;
font-family: 'Urbanist', sans-serif;
font-size: 20px;
line-height: 0px;
margin-top: -740; //I added negative margins because this element was being pushed downwards and that solved it, but I don't want to have to do it with every new element.
}
body {
padding: 0;
margin: 0;
}
header {
height: 60px;
background-color: #1e3799;
}
ul {
float: right;
right: 30%;
}
ul li {
display: inline;
list-syle: none;
}
ul li a {
text-decoration: none;
color: white;
font-family: 'Urbanist', sans-serif;
font-size: 18px;
padding: 0px 0px 0px 20px;
}
footer {
position: absolute;
bottom: 0%;
width: 100%;
height: 60px;
background-color: #1e3799;
text-align: center;
margin: 0 auto;
}
footer p {
color: white;
font-family: 'Urbanist', sans-serif;
}
body {
background-color: #4a69bd;
}
<h1>Log In</h1>
<p> No Account?<a href="register.php">Register here!</p>

Answer 1

Don't use width and height 100% for *.
This * means use it every element on
p {
color: white;
font-family: 'Urbanist', sans-serif;
font-size: 20px;
line-height: 0px;
margin-top: -740; /* You forgot to add 'px' here */
}
Change this to these to full page with preserving background color.
* {
padding: 0;
margin: 0;
}
body {
width: 100%;
height: 100%;
}
You also forgot to close <p> No Account?Register here!</p> tag.
I don't suggest you use this if you don't know what you are doing line-height: 0px;
Here is complete fixed code. I aligned some items because the way of coding I thought you want to center footer items.
* {
padding: 0;
margin: 0;
}
h1 {
color: white;
font-family: 'Urbanist', sans-serif;
font-size: 30px;
/* line-height: 0px; */
margin-bottom: 0px;
}
p {
color: white;
font-family: 'Urbanist', sans-serif;
font-size: 20px;
/* line-height: 0px; */
/* margin-top: -740; */
/* You forgot to add 'px' here */
}
body {
background-color: #4a69bd;
width: 100%;
height: 100%;
}
footer {
position: absolute;
bottom: 0%;
width: 100%;
height: 60px;
background-color: #1e3799;
}
footer, p {
display: flex;
justify-content: center;
align-items: center;
color: white;
font-family: 'Urbanist', sans-serif;
}
a {
margin-left: 10px;
color: white;
}
<h1>Log In</h1>
<footer>
<p> No Account?Register here!</p>
</footer>

Answer 2

It may be because you have given all (*) a height of 100% in your css