HTML/CSS sign up form - html

Question

I am currently working on creating a sign up form html/css. I realised that different browsers work differently on the width of inputs. How can i rectify this issue and make sure that my sign up form is compatible with all browsers. My sign up form works perfectly for chrome as it is where i do coding on.
ul {
background-color: #000000;
}
li a:hover {
background-color: #0cf72a;
}
.word-container {
width: 500px;
height: 50px;
margin: auto;
position: relative;
top: 80px;
}
.word-container h1 {
margin: 0;
text-align: center;
color: #ab0a0a;
}
.register-container {
width: 600px;
height: 350px;
margin: auto;
position: relative;
top: 100px;
border: 1px solid #000;
}
.fname input[type="text"] {
position: relative;
left: 115px;
top: 30px;
padding: 8px;
}
.lname input[type="text"] {
position: relative;
left: 314px;
top: -5.5px;
padding: 8px;
}
.userid input[type="text"] {
position: relative;
left: 115px;
padding: 8px;
top: 10px;
}
.pwd input[type="password"] {
position: relative;
padding: 8px;
left: 115px;
top: 25px;
}
.email input[type="email"] {
position: relative;
padding: 8px;
left: 115px;
top: 40px;
}
.btn button[type="submit"] {
position: relative;
left: 115px;
top: 55px;
padding: 8px;
width: 382px;
border: 1px solid #000000;
color: #ffffff;
background-color: #ab0a0a;
}
div.btn button[type="submit"]:hover {
background-color: rgb(255, 0, 0);
}
<div class="word-container">
<h1>Create your account</h1>
</div>
<div class="register-container">
<form action="" method="POST">
<div class="fname">
<label>
<input type="text" placeholder="First Name" name="fname" size="20">
</label>
</div>
<div class="lname">
<label>
<input type="text" placeholder="Last Name" name="lname" size="20">
</label>
</div>
<div class="userid">
<label>
<input type="text" placeholder="Username" name="userid" size="50">
</label>
</div>
<div class="pwd">
<label>
<input type="password" placeholder="Password" name="pwd" size="50">
</label>
</div>
<div class="email">
<label>
<input type="email" placeholder="Email Address" name="email" size="50">
</label>
</div>
<div class="btn">
<button type="submit">Create Account</button>
</div>
</form>
</div>

Answer 1

It's always a good idea to use something like normalize.css or any other CSS reset code (eric meyer css reset is very popular too) to reset CSS across all browsers.
Any browser come with it's defaults values for padding's,margins,widths, heights etc...
I guess it won't be an 100% solution but it will defiantly will take you closer to what you're looking for.

Answer 2

Do not jump to position relative and absolute. If you are new to all this, I can understand it seems the most natural way to go about positioning elements; just using a top and left position and that's that. But this is not how you should do it on the web!
Below you can find how I would do it.
Matan G. is right in pointing out that a CSS reset/normalize is often used, and I do so myself as well. However, before you do that (and considering you're new) it would be wise to take a look at the code that I posted and see if it makes any sense to you. If not, ask.
It is important to note that you should avoid these things when possible:
setting a fixed width to text items such as headings, paragraphs, lists.
using relative/absolute positioning. They are very useful but only when necessary.
using too many divs/classes than actually needed. Don't overcrowd your HTML.
* {box-sizing: border-box;}
ul {
background-color: #000000;
}
li a:hover {
background-color: #0cf72a;
}
.word-container {
width: 500px;
height: 50px;
margin: 80px auto auto;
}
.word-container h1 {
margin: 0;
text-align: center;
color: #ab0a0a;
}
.register-container {
width: 600px;
margin: 20px auto auto;
border: 1px solid #000;
padding: 20px;
}
label {
display: block;
}
.name::after {
content: "";
display: table;
clear: both;
}
.name label:first-child {
margin-right: 20px;
}
.name label {
width: calc(100% / 2 - 10px);
float: left;
}
input, [type="submit"] {
padding: 8px;
margin-bottom: 20px;
width: 100%;
}
[type="submit"] {
border: 1px solid #000000;
color: #ffffff;
background-color: #ab0a0a;
margin: 0;
}
[type="submit"]:hover {
background-color: red;
}
<div class="word-container">
<h1>Create your account</h1>
</div>
<div class="register-container">
<form action="" method="POST">
<div class="name">
<label>
<input type="text" placeholder="First Name" name="fname">
</label>
<label>
<input type="text" placeholder="Last Name" name="lname">
</label>
</div>
<label>
<input type="text" placeholder="Username" name="userid">
</label>
<label>
<input type="password" placeholder="Password" name="pwd">
</label>
<label>
<input type="email" placeholder="Email Address" name="email">
</label>
<button type="submit">Create Account</button>
</form>
</div>

Answer 3

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>HTML Forms</title>
<style>
.container{
width: 45%;
margin: auto;
}
.form-content{
margin: 40px;
}
.form-content input{
width: 100%;
}
label{
font-weight: bold;
}
input[type=text],[type=email],[type=tel],[type=date],[type=password]{
font-size: 16px;
border-radius: 5px;
background: #D9F1F7;
border: #000000;
padding: 10px;
}
input[type=submit]{
background: #4C63ED;
padding: 10px;
border: none;
border-radius: 5px;
font-size: 16px;
color: #fff;
cursor: pointer;
}
input[type=submit]:hover{
background: #330EEF;
font-weight: bold;
}
</style>
</head>
<body>
<div class = "container">
<form name="signup" method="get" action="">
<div class="form-content">
<label>First Name : </label>
<input type="text" name="firstname" />
</div>
<div class="form-content">
<label>Last Name : </label>
<input type="text" name="lastname" />
</div>
<div class="form-content">
<label>E-Mail : </label>
<input type="email" name="email" />
</div>
<div class="form-content">
<label>Telephone : </label>
<input type="tel" name="telephone" />
</div>
<div class="form-content">
<label>Date of Birth : </label>
<input type="date" name="dob" />
</div>
<div class="form-content">
<input type="submit" name="submit" value="Submit" />
</div>
</form>
</div>
</body>
</html>