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HTML 

              
                <div class="row">
  <div class="first-title">1 Personal Information</div>
  <div class="col col-span-7">
    <form>
      <div class="container">

        <div class="box--half">
          <label>First Name</label>
          <input type="text" id="f_name" name="firstName" placeholder="Elon" maxlength="20" required>
          <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--half">
          <label>Last Name</label>
          <input type="text" id="l_name" name="l_name" placeholder="Musk" required> <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--full">
          <label>Email</label>
          <input id="email" name="email" type="email" placeholder="elon@spacex.com" required>
          <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--half">
          <label>Country</label>
          <select name="country" id="country" required>
<option value="Default">(Please choose a country)</option> 
<option value="US">United States</option>
</select>
          <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--half">
          <label>Postal Code</label>
          <input type="text" id="p_code" name="p_code" placeholder="10001" maxlength="5" required>
          <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--full">
          <label>Phone Number</label>
          <input type="tel" id="tel" name="tel" placeholder="(292) 692-93-92" id="tel" maxlength="15" required>
          <span class="error" aria-live="polite"></span>
        </div>
      </div>
      <div class="second-title">2 Payment Details</div>
      <div class="container">
        <div class="box--full">
          <label>Credit Card Number</label>
          <input type="text" id="cc_number" name="cc_number" placeholder="0000-0000-0000-0000" maxlength="19" required>
          <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--half">
          <label>Security Code</label>
          <input type="text" id="sec_code" name="sec_code" placeholder="***" maxlength="3" required>
          <span class="error" aria-live="polite"></span>
        </div>
        <div class="box--half">
          <label>Expiration Date</label>
          <input type="text" id="exp_date" name="exp_date" placeholder="MM/YY" required>
          <span class="error" aria-live="polite"></span>
        </div>
        <input type="button" id="submit" value="Complete Purchase" onclick="validate()">
      </div>
    </form>
  </div>
  <div class="col col-span-2">
    <div class="container cart">
      <div class="box--full">
        <table>
          <tr>
            <th colspan="2">YOUR ORDER</th>
          </tr>
          <tr>
            <td>Apple Watch Sport</td>
            <td class="right">$ 580</td>
          </tr>
          <tr>
            <td>Modern Buckle</td>
            <td class="right">$ 380</td>
          </tr>
          <tr>
            <th colspan="2" class="table-border"></th>
          </tr>
          <tr>
            <td>Total Purchases</td>
            <td class="right">$ 960</td>
          </tr>
          <tr>
            <td>Estimated Tax</td>
            <td class="right">$ 0</td>
          </tr>
          <tr>
            <th colspan="2" class="table-border"></th>
          </tr>
          <tr>
            <td>Total</td>
            <td class="total">$ 960</td>
          </tr>
        </table>
      </div>
    </div>
  </div>
</div>
!

CSS 

              
                ///// Some useful mixins
@mixin button-form {
  padding: 1.5rem;
  margin: .5rem;
  border: 0 none;
  font-size: 1.5em;
  border-bottom: 3px solid #5bb500;
  background-color: #6bd400;
  font-weight: $font-weight;
  color: #fff;
  &:hover,
  &:focus {
    cursor: pointer;
  }
}

//box model = border-box
@mixin box-sizing($box-model) {
  -webkit-box-sizing: $box-model; // Safari <= 5
  -moz-box-sizing: $box-model; // Firefox <= 19
  box-sizing: $box-model;
}

@mixin titles {
  font-family: "Roboto", "Helvetica", "Arial", sans-serif;
  font-size: 1em;
  font-weight: $font-weight;
  line-height: 1;
  letter-spacing: .02em;
  text-transform: uppercase;
}

///// Variables
$font-weight: bold;
$text-color: #2f383d;
$dotted: 2px dotted #D1D1D1;
$radius: 4px;
// form styles
* {
  @include box-sizing(border-box);
}

// Flexbox Styles
//Outer container
.row {
  margin-top: 0.5rem;
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  width: 80%;
  margin: 0 auto;
  background-color: #f1f1f1;
}

.col {
  flex: 1 1 8%;
  margin: 0 0 0.5rem 0;
  padding: 0.5em 10px;
  box-sizing: border-box;
}

.col-span-7 {
  flex-basis: 58.3333%;
}

.col-span-2 {
  flex-basis: 16.6666%;
}

// Inner Container
.container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-flow: row wrap;
}

[class*="box--"] {
  display: flex;
  margin: .5rem;
  background: white;
  border-bottom: 3px solid #dedfdf;
}

.box--full {
  flex: 1 1 100%;
  flex-flow: column;
  padding: 1rem;
  border-radius: $radius;
}

.box--half {
  flex: 1 1 30%;
  flex-flow: column;
  padding: 1rem;
  border-radius: $radius;
  flex-shrink: 1;
  flex-basis: 250px; //effectively it's min width
}

@media all and (max-width: 568px) {
  .col-span-2 {
    flex-basis: 50%;
  }
  .col-span-6,
  .col-span-7,
  {
    flex-basis: 100%;
  }
}

// get rid of "default" iOS button styling for submit buttons
input[type=submit] {
  appearance: none;
}

// Most form inputs
input[type="email"],
input[type="password"],
input[type="text"],
input[type="search"],
input[type="tel"],
input[type="number"],
input[type="url"],
textarea {
  font-size: 1.3em;
  width: 100%;
}

label {
  font-weight: $font-weight;
  color: #000;
  font-size: 1em;
}

// Selects (dropdowns)
select {
  font-size: 1.3em;
  height: 2.1rem;
  line-height: 1.5em;
  width: 100%;
  margin-top: .25rem;
  background: transparent;
  &:hover {
    cursor: pointer;
  }
}

input,
select {
  border: none;
  padding-top: .5rem;
  padding-bottom: .5rem;
}

textarea:focus,
input:focus {
  outline: none;
}

.first-title {
  @include titles;
  width: 100%;
  padding-left: 10px;
  margin: 24px 0 16px;
}

.second-title {
  @include titles;
  width: 100%;
  margin: 30px 0 20px;
}

#submit {
  @include button-form;
  width: 100%;
  border-radius: $radius;
}

.error {
  color: orangered;
}

.cart {
  outline: $dotted;
  outline-offset: -13px;
}

table {
  width: 100%;
}

td,
th {
  padding: 10px;
  white-space: nowrap;
  text-align: left;
}

th {
  font-weight: $font-weight;
}

.total {
  font-weight: $font-weight;
  font-size: 2em;
  text-align: right;
}

.right {
  text-align: right;
}

.table-border {
  border-bottom: $dotted;
}
!

JS 

              
                var firstName = document.getElementById("f_name");
var lastName = document.getElementById("l_name");
var eMail = document.getElementById("email");
var select = document.getElementById("country");
var postalCode = document.getElementById("p_code");
var phoneNumber = document.getElementById("tel");
var ccNumber = document.getElementById("cc_number");
var securityCode = document.getElementById("sec_code");
var expirationDate = document.getElementById("exp_date");
var emailFormat = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
var ccFormat = /^\(?([0-9]{4})\)?[-. ]?([0-9]{4})[-. ]?([0-9]{4})?[-. ]?([0-9]{4})$/;
var numbers = /^[0-9]+$/;
var error = true;

function validate() {
  //checking fields
  if (firstName.value.length == 0 || firstName.value.length > 20 || firstName.value.match(numbers)) {
    var parent = firstName.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = firstName.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (lastName.value.length == 0 || lastName.value.length > 20 || lastName.value.match(numbers)) {
    var parent = lastName.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = lastName.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (!eMail.value.match(emailFormat)) {
    var parent = eMail.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = eMail.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (select.value == "Default") {
    var parent = select.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = select.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (!postalCode.value.match(numbers) || postalCode.value.length > 5) {
    var parent = postalCode.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = postalCode.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (!phoneNumber.value.match(/^\d{10}$/)) {
    var parent = phoneNumber.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = phoneNumber.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (!ccNumber.value.match(ccFormat)) {
    var parent = ccNumber.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = ccNumber.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (!securityCode.value.match(numbers) || securityCode.value.length == 0 || securityCode.value.length > 3) {
    var parent = securityCode.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = securityCode.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  if (expirationDate.value.length == 0 || expirationDate.value.length > 5) {
    var parent = expirationDate.parentElement;
    parent.querySelector(".error").innerText = "Required";
    parent.querySelector(".error").style.display = "block";
    error = true;
  } else {
    error = false;
    var parent = expirationDate.parentElement;
    parent.querySelector(".error").style.display = "none";
  }
  console.log(error);
  if (error == false) {
    window.location.assign('https://www.google.com');
  }

}
!
999px

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