Check out example codes for "forms html css". It will help you in understanding the concepts better.

Code Example 1

table, th, td {
    padding: 1.5%;
    border: 1px solid white;
    text-align: center;
}

button{
    width: 100%;
    height: 100%;
    padding: 2px ;
    margin: 2px;
}

body {
    background-image: url(https://images.unsplash.com/photo-1574375927938-d5a98e8ffe85?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1949&q=80);
    height: 100%;
    
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    color: honeydew;
}

.h1-header, h1{
    text-align: center;
    width: 100%;
    height: 70px;
    font-size: 14px;
    padding-top:0px ;
}
h1 {
    font-size: 36px;
    font-style: italic;

}
.form1 {
    float: left;

width: 20%;
height: 300px;
margin: 150px 0 0 200px;
    background-color: #3a303099;

}
.form1 #form {
    color: honeydew;
    
}
form{
    padding: 50px;
    }
    

.table {
    width: 35%;
    margin: 150px 200px 0 800px;

}

table{
padding: 50px 120px;
}

Code Example 2

<!DOCTYPE html>
<html>
<style>
input[type=text], select {
  width: 100%;
  padding: 12px 20px;
  margin: 8px 0;
  display: inline-block;
  border: 1px solid #ccc;
  border-radius: 4px;
  box-sizing: border-box;
}

input[type=submit] {
  width: 100%;
  background-color: #4CAF50;
  color: white;
  padding: 14px 20px;
  margin: 8px 0;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

input[type=submit]:hover {
  background-color: #45a049;
}

div {
  border-radius: 5px;
  background-color: #f2f2f2;
  padding: 20px;
}
</style>
<body>

<h3>Using CSS to style an HTML Form</h3>

<div>
  <form action="/action_page.php">
    <label for="fname">First Name</label>
    <input type="text" id="fname" name="firstname" placeholder="Your name..">

    <label for="lname">Last Name</label>
    <input type="text" id="lname" name="lastname" placeholder="Your last name..">

    <label for="country">Country</label>
    <select id="country" name="country">
      <option value="australia">Australia</option>
      <option value="canada">Canada</option>
      <option value="usa">USA</option>
    </select>
  
    <input type="submit" value="Submit">
  </form>
</div>

</body>
</html>

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