registration_style.css

<style>
* {
    box-sizing: border-box;
}
.header {
    border: 1px solid green;
    padding: 15px;
}
.row::after {
    content: "";
    clear: both;
    display: table;
}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

li {
    float: left;
}

li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

li a:hover {
    background-color: #111;
}

[class*="col-"] {
    float: left;
    padding: 15px;
    border: 3px solid blue;
}

/* This is allocating layout spaces for how the website is going to be allocated the spaces for different contencts. */

.col-1 {width: 8.33%;}
.col-2 {width: 16.66%;}
.col-3 {width: 25%;}
.col-4 {width: 33.33%;}
.col-5 {width: 41.66%;}
.col-6 {width: 50%;}
.col-7 {width: 58.33%;}
.col-8 {width: 66.66%;}
.col-9 {width: 75%;}
.col-10 {width: 83.33%;}
.col-11 {width: 91.66%;}
.col-12 {width: 100%;}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

li {
    float: left;
}

li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

li a:hover:not(.active) {
    background-color: #111;
}

.active {
    background-color: #4CAF50;
}

@import url(https://fonts.googleapis.com/css?family=Roboto:400,300,600,400italic);
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
  -moz-font-smoothing: antialiased;
  -o-font-smoothing: antialiased;
  font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body {
  font-family: "Roboto", Helvetica, Arial, sans-serif;
  font-weight: 100;
  font-size: 15px;
  line-height: 30px;
  color: #777;
  background: #ffffff;
}

.container {
  max-width: 400px;
  width: 100%;
  margin: 0 auto;
  position: relative;
}

#registration input[type="first_name"],
#registration input[type="last_name"],
#registration input[type="username"],
#registration input[type="password"],
#registration button[type="submit"] {
  font: 400 12px/16px "Roboto", Helvetica, Arial, sans-serif;
}

#registration {
  background: #F9F9F9;
  padding: 25px;
  margin: 15px 0;
  box-shadow: 0 0 20px 0 rgba(0, 0, 0, 0.2), 0 5px 5px 0 rgba(0, 0, 0, 0.24);
}

#registration h3 {
  display: block;
  font-size: 30px;
  font-weight: 300;
  margin-bottom: 10px;
}

#registration h4 {
  margin: 5px 0 15px;
  display: block;
  font-size: 13px;
  font-weight: 400;
}

fieldset {
  border: medium none !important;
  margin: 0 0 10px;
  min-width: 100%;
  padding: 0;
  width: 100%;
}

#registration input[type="first_name"],
#registration input[type="last_name"],
#registration input[type="username"],
#registration input[type="password"] {
  width: 100%;
  border: 1px solid #ccc;
  background: #FFF;
  margin: 0 0 5px;
  padding: 10px;
}

#registration input[type="first_name"]:hover,
#registration input[type="last_name"]:hover,
#registration input[type="username"]:hover,
#registration input[type="password"]:hover {
  -webkit-transition: border-color 0.3s ease-in-out;
  -moz-transition: border-color 0.3s ease-in-out;
  transition: border-color 0.3s ease-in-out;
  border: 1px solid #aaa;
}

#registration button[type="submit"] {
  cursor: pointer;
  width: 100%;
  border: none;
  background: #4CAF50;
  color: #FFF;
  margin: 0 0 5px;
  padding: 10px;
  font-size: 20px;
}

#registration button[type="submit"]:hover {
  background: #43A047;
  -webkit-transition: background 0.3s ease-in-out;
  -moz-transition: background 0.3s ease-in-out;
  transition: background-color 0.3s ease-in-out;
}

#registration button[type="submit"]:active {
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.5);
}

#registration input:focus,
#registration textarea:focus {
  outline: 0;
  border: 1px solid #aaa;
}

::-webkit-input-placeholder {
  color: #888;
}

:-moz-placeholder {
  color: #888;
}

::-moz-placeholder {
  color: #888;
}

:-ms-input-placeholder {
  color: #888;
}

</style>