how to make sizes look the same on all screens - html

Question

So, I am working on two sites, and the padding seems to change tremendously on different screens, I was wondering if this was potentially due to the units I am using? Or the specific CSS tag? However, I am hoping someone can figure it out for me
Two bits of code that keep changing:
codepen
.divider {
background-color: #3498db;
padding-top: 5%;
padding-bottom: 5%;
font-family: Open Sans;
font-weight: 300;
text-align: center;
}
.divider h1 {
margin-bottom: 10px;
margin-top: 0%;
padding-top: 20%;
font-weight: 500;
color: white;
}
.divider p {
color: white;
margin-bottom: 5px;
font-family: Open Sans;
text-align: center;
}
.divider button {
padding: 10px;
height: 15%;
cursor: auto;
width: 17%;
margin-top: 30px;
border-radius: 50px;
text-align: center;
color: white;
border: white 1px solid;
background-color: #3498db;
}
.divider button:hover {
background-color: white;
color: black;
transition: all 0.3s ease 0s;
}
<div class="divider">
<h1>See Something You Like?</h1>
<p>Feel free to contact us at any time and we’ll have someone reply to you 6 as soon as possible.
<br>industry's standard dummy text ever since the 1500s
<br>
<br>Whenever you’re ready, email us with the details you want on your website, and we will
<br>respond with a rough price.</p>
<a href="mailto:hello#baseframe.co">
<button>Email</button>
</a>
</div>
on this, the top padding gets super big (or sometimes it gets smaller) on different screens.
codepen
* {
margin: 0 auto;
padding: 0;
}
html {
height: 100%;
}
body {
font-family: 'Open Sans';
font-weight: 400;
height: 100%;
background-color: #ddd;
}
.nav {
background: rgba(0, 0, 0, 0);
position: absolute;
width: 100%;
}
.nav ul {
text-align: right;
vertical-align: middle;
margin-right: 15px;
margin-top: 15px;
font-size: 1.1em;
}
.nav li {
padding-top: 5px;
list-style: none;
display: inline-block;
padding: 15px;
}
.nav a {
margin-top: 17px;
bottom: 0;
display: inline-block;
color: white;
text-decoration: none;
}
.nav a:hover {
color: #3498db;
transition: ease 0.5s all 0s;
}
.nav hr {
opacity: 0.2;
width: 95%;
text-align: center;
}
.nav-logo {
vertical-align: middle;
top: 0;
float: left;
width: 5%;
display: inline-block;
}
.nav-logo img {
width: 250%;
box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.3);
}
/*-------------------Home-Page-------------------*/
.home-page {
background-image: url("http://baseframe.co/getanimus/img/cover1.jpg");
background-size: cover;
background-position: top;
background-attachment: fixed;
padding-bottom: 17%;
text-align: center;
}
.home-page h1 {
color: white;
padding-top: 15%;
font-size: 5em;
text-shadow: 0px 0px 10px rgba(0, 0, 0, 0.3);
}
.home-page input {
cursor: auto;
}
.home-page p {
font-weight: 300;
color: white;
margin-bottom: 15px;
}
button#infl {
background-color: #3498db;
color: white;
font-size: 1em;
width: 15%;
box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.3);
font-family: montserrat;
padding: 15px;
margin: 5px;
border-top-left-radius: 2em;
border-top-right-radius: 2em;
border-bottom-left-radius: 2em;
border-bottom-right-radius: 2em;
border: none;
cursor: auto;
}
button#brands {
background-color: white;
color: #7f8c8d;
font-size: 1em;
width: 15%;
box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.3);
font-family: montserrat;
padding: 15px;
margin: 5px;
border-top-left-radius: 2em;
border-top-right-radius: 2em;
border-bottom-left-radius: 2em;
border-bottom-right-radius: 2em;
border: none;
cursor: auto;
}
button#brands:hover {
opacity: 0.8;
transition: all 0.3s ease 0s;
}
button#infl:hover {
opacity: 0.8;
transition: all 0.3s ease 0s;
}
/*-------------------About-------------------*/
.about {
background-color: white;
padding-bottom: 10%;
}
.about h1 {
text-align: left;
margin-left: 20%;
margin-top: 5%;
}
.about hr {
background-color: #3498db;
height: 5px;
border: none;
margin-top: 2%;
margin-left: 20%;
width: 5%;
text-align: left;
float: left
}
.about p {
margin-left: 20%;
margin-right: 20%;
line-height: 30px;
margin-top: 5%;
text-align: left;
}
<div class="nav">
<ul>
<li class="nav-logo">
<img src="http://baseframe.co/getanimus/img/logo_white.png">
</li>
<li>Home</li>
<li>Influencers</li>
<li>Brands</li>
<li>Contact</li>
<hr>
</div>
<div class="home-page">
<h1>Animus Digital</h1>
<p>Premium Talent Management Agency</p>
<button id="infl">Influencers</button>
<button id="brands">Brands</button>
</div>
this website navigation doesn't align properly with the logo on the left, for some reason. In addition, on a 1920 x 1080 screen, the buttons get pretty wide.
Really appreciate any help on this. Thanks.

Answer 1

The reason why the sizes of those elements changes on different screens is because you use % instead of px. % scales the size with the browser's size.
You should use CSS Media queries

Answer 2

For first case since you are using % in padding, which leads to unexpected behavior in different situations.
For "n%" margin (and padding) to be the same for
margin-top/margin-right/margin-bottom/margin-left, all four have to be
relative to the same base. If top/bottom used a different base than
left/right', then "n%" margin (and padding) wouldn't mean the same
thing on all four sides.
(Also note having the top/bottom margin relative to the width enables
a weird CSS hack that allows you to specify a box with an unchanging
aspect ratio ...even if the box is rescaled.)
% with margin/padding