How to make my form responsive - HTML and CSS

Question

I've been working on a dynamic form here: https://jsfiddle.net/whvzvmL8/

Right now, I am using tables since this is a machine generated codes.

Here's my HTML:

    <div style="border: 1px solid #ABABAB; padding: 30px; -webkit-border-radius: 8px; -moz-border-radius: 8px; border-radius: 8px; text-align: center; width: 50%; margin: 0 auto;">

  <h1>FORM</h1>


  <div class="default beta-base beta-font-b" id="mainContent" style="height:100%">
    <table cellpadding="10" cellspacing="0" class="background" style="width: 100%; height: 100%">
      <tbody>
        <tr>
          <td align="center" valign="top">
            <table bgcolor="#FFFFFF" cellpadding="20" cellspacing="0" class="bodyContainer webFormBodyContainer" width="100%">
              <tbody>
                <tr>
                  <td bgcolor="#FFFFFF" class="body" sectionid="body" valign="top">
                    <form accept-charset="UTF-8" action="https://xt348.infusionsoft.com/app/form/process/a74884c5636f18aad3994210d4205f39" class="infusion-form" method="POST">
                      <input name="inf_form_xid" type="hidden" value="a74884c5636f18aad3994210d4205f39" />
                      <input name="inf_form_name" type="hidden" value="Contact Us&#a;Form" />
                      <input name="infusionsoft_version" type="hidden" value="1.62.0.53" />
                      <div>
                        <table class="infusion-field-container" style="width:100%;">
                          <tbody>
                            <tr>
                              <td class="infusion-field-label-container">
                                <label for="inf_field_FirstName">First Name *</label>
                              </td>
                              <td class="infusion-field-input-container" style="width:200px;">
                                <input class="infusion-field-input-container" id="inf_field_FirstName" name="inf_field_FirstName" type="text" />
                              </td>
                            </tr>
                            <tr>
                              <td class="infusion-field-label-container">
                                <label for="inf_field_LastName">Last Name *</label>
                              </td>
                              <td class="infusion-field-input-container" style="width:200px;">
                                <input class="infusion-field-input-container" id="inf_field_LastName" name="inf_field_LastName" type="text" />
                              </td>
                            </tr>
                          </tbody>
                        </table>
                      </div>
                      <div>
                        <table class="infusion-field-container" style="width:100%;">
                          <tbody>
                            <tr>
                              <td class="infusion-field-label-container">
                                <label for="inf_field_Email">Email *</label>
                              </td>
                              <td class="infusion-field-input-container" style="width:200px;">
                                <input class="infusion-field-input-container" id="inf_field_Email" name="inf_field_Email" type="text" />
                              </td>
                            </tr>
                          </tbody>
                        </table>
                      </div>
                      <div>
                        <table class="infusion-field-container" style="width:100%;">
                          <tbody>
                            <tr>
                              <td class="infusion-field-label-container">
                                <label for="inf_field_Phone1">Phone *</label>
                              </td>
                              <td class="infusion-field-input-container" style="width:200px;">
                                <input class="infusion-field-input-container" id="inf_field_Phone1" name="inf_field_Phone1" type="text" />
                              </td>
                            </tr>
                          </tbody>
                        </table>
                      </div>
                      <div>
                        <table class="infusion-field-container" style="width:100%;">
                          <tbody>
                            <tr>
                              <td class="infusion-field-label-container">
                                <label for="inf_custom_Country0">Country</label>
                              </td>
                              <td class="infusion-field-input-container" style="width:200px;">
                                <select id="inf_custom_Country0" name="inf_custom_Country0"><option value="">Please select one</option><option value="Afghanistan">Afghanistan</option><option value="Albania">Albania</option><option value="Algeria">Algeria</option><option value="Andorra">Andorra</option><option value="Angola">Angola</option><option value="Antigua and Barbuda">Antigua and Barbuda</option><option value="Argentina">Argentina</option><option value="Armenia">Armenia</option><option value="Australia">Australia</option><option value="Austria">Austria</option><option value="Azerbaijan">Azerbaijan</option><option value="Bahamas">Bahamas</option><option value="Bahrain">Bahrain</option><option value="Bangladesh">Bangladesh</option><option value="Barbados">Barbados</option><option value="Belarus">Belarus</option><option value="Belgium">Belgium</option><option value="Belize">Belize</option><option value="Benin">Benin</option><option value="Bhutan">Bhutan</option><option value="Bolivia">Bolivia</option><option value="Bosnia and Herzegovina">Bosnia and Herzegovina</option><option value="Botswana">Botswana</option><option value="Brazil">Brazil</option><option value="Brunei">Brunei</option><option value="Bulgaria">Bulgaria</option><option value="Burkina Faso">Burkina Faso</option><option value="Burundi">Burundi</option><option value="Cabo Verde">Cabo Verde</option><option value="Cambodia">Cambodia</option><option value="Cameroon">Cameroon</option><option value="Canada">Canada</option><option value="Central African Republic (CAR)">Central African Republic (CAR)</option><option value="Chad">Chad</option><option value="Chile">Chile</option><option value="China">China</option><option value="Colombia">Colombia</option><option value="Comoros">Comoros</option><option value="Democratic Republic of the Congo">Democratic Republic of the Congo</option><option value="Republic of the Congo">Republic of the Congo</option><option value="Costa Rica">Costa Rica</option><option value="Cote d'Ivoire">Cote d'Ivoire</option><option value="Croatia">Croatia</option><option value="Cuba">Cuba</option><option value="Cyprus">Cyprus</option><option value="Czech Republic">Czech Republic</option><option value="Denmark">Denmark</option><option value="Djibouti">Djibouti</option><option value="Dominica">Dominica</option><option value="Dominican Republic">Dominican Republic</option><option value="Ecuador">Ecuador</option><option value="Egypt">Egypt</option><option value="El Salvador">El Salvador</option><option value="Equatorial Guinea">Equatorial Guinea</option><option value="Eritrea">Eritrea</option><option value="Estonia">Estonia</option><option value="Ethiopia">Ethiopia</option><option value="Fiji">Fiji</option><option value="Finland">Finland</option><option value="France">France</option><option value="Gabon">Gabon</option><option value="Gambia">Gambia</option><option value="Georgia">Georgia</option><option value="Germany">Germany</option><option value="Ghana">Ghana</option><option value="Greece">Greece</option><option value="Grenada">Grenada</option><option value="Guatemala">Guatemala</option><option value="Guinea">Guinea</option><option value="Guinea-Bissau">Guinea-Bissau</option><option value="Guyana">Guyana</option><option value="Haiti">Haiti</option><option value="Honduras">Honduras</option><option value="Hungary">Hungary</option><option value="Iceland">Iceland</option><option value="India">India</option><option value="Indonesia">Indonesia</option><option value="Iran">Iran</option><option value="Iraq">Iraq</option><option value="Ireland">Ireland</option><option value="Israel">Israel</option><option value="Italy">Italy</option><option value="Jamaica">Jamaica</option><option value="Japan">Japan</option><option value="Jordan">Jordan</option><option value="Kazakhstan">Kazakhstan</option><option value="Kenya">Kenya</option><option value="Kiribati">Kiribati</option><option value="Kosovo">Kosovo</option><option value="Kuwait">Kuwait</option><option value="Kyrgyzstan">Kyrgyzstan</option><option value="Laos">Laos</option><option value="Latvia">Latvia</option><option value="Lebanon">Lebanon</option><option value="Lesotho">Lesotho</option><option value="Liberia">Liberia</option><option value="Libya">Libya</option><option value="Liechtenstein">Liechtenstein</option><option value="Lithuania">Lithuania</option><option value="Luxembourg">Luxembourg</option><option value="Macedonia">Macedonia</option><option value="Madagascar">Madagascar</option><option value="Malawi">Malawi</option><option value="Malaysia">Malaysia</option><option value="Maldives">Maldives</option><option value="Mali">Mali</option><option value="Malta">Malta</option><option value="Marshall Islands">Marshall Islands</option><option value="Mauritania">Mauritania</option><option value="Mauritius">Mauritius</option><option value="Mexico">Mexico</option><option value="Micronesia">Micronesia</option><option value="Moldova">Moldova</option><option value="Monaco">Monaco</option><option value="Mongolia">Mongolia</option><option value="Montenegro">Montenegro</option><option value="Morocco">Morocco</option><option value="Mozambique">Mozambique</option><option value="Myanmar (Burma)">Myanmar (Burma)</option><option value="Namibia">Namibia</option><option value="Nauru">Nauru</option><option value="Nepal">Nepal</option><option value="Netherlands">Netherlands</option><option value="New Zealand">New Zealand</option><option value="Nicaragua">Nicaragua</option><option value="Niger">Niger</option><option value="Nigeria">Nigeria</option><option value="North Korea">North Korea</option><option value="Norway">Norway</option><option value="Oman">Oman</option><option value="Pakistan">Pakistan</option><option value="Palau">Palau</option><option value="Palestine">Palestine</option><option value="Panama">Panama</option><option value="Papua New Guinea">Papua New Guinea</option><option value="Paraguay">Paraguay</option><option value="Peru">Peru</option><option value="Philippines">Philippines</option><option value="Poland">Poland</option><option value="Portugal">Portugal</option><option value="Qatar">Qatar</option><option value="Romania">Romania</option><option value="Russia">Russia</option><option value="Rwanda">Rwanda</option><option value="Saint Kitts and Nevis">Saint Kitts and Nevis</option><option value="Saint Lucia">Saint Lucia</option><option value="Saint Vincent and the Grenadines">Saint Vincent and the Grenadines</option><option value="Samoa">Samoa</option><option value="San Marino">San Marino</option><option value="Sao Tome and Principe">Sao Tome and Principe</option><option value="Saudi Arabia">Saudi Arabia</option><option value="Senegal">Senegal</option><option value="Serbia">Serbia</option><option value="Seychelles">Seychelles</option><option value="Sierra Leone">Sierra Leone</option><option value="Singapore">Singapore</option><option value="Slovakia">Slovakia</option><option value="Slovenia">Slovenia</option><option value="Solomon Islands">Solomon Islands</option><option value="Somalia">Somalia</option><option value="South Africa">South Africa</option><option value="South Korea">South Korea</option><option value="South Sudan">South Sudan</option><option value="Spain">Spain</option><option value="Sri Lanka">Sri Lanka</option><option value="Sudan">Sudan</option><option value="Suriname">Suriname</option><option value="Swaziland">Swaziland</option><option value="Sweden">Sweden</option><option value="Switzerland">Switzerland</option><option value="Syria">Syria</option><option value="Taiwan">Taiwan</option><option value="Tajikistan">Tajikistan</option><option value="Tanzania">Tanzania</option><option value="Thailand">Thailand</option><option value="Timor-Leste">Timor-Leste</option><option value="Togo">Togo</option><option value="Tonga">Tonga</option><option value="Trinidad and Tobago">Trinidad and Tobago</option><option value="Tunisia">Tunisia</option><option value="Turkey">Turkey</option><option value="Turkmenistan">Turkmenistan</option><option value="Tuvalu">Tuvalu</option><option value="Uganda">Uganda</option><option value="Ukraine">Ukraine</option><option value="United Arab Emirates (UAE)">United Arab Emirates (UAE)</option><option value="United Kingdom (UK)">United Kingdom (UK)</option><option value="United States of America (USA)">United States of America (USA)</option><option value="Uruguay">Uruguay</option><option value="Uzbekistan">Uzbekistan</option><option value="Vanuatu">Vanuatu</option><option value="Vatican City (Holy See)">Vatican City (Holy See)</option><option value="Venezuela">Venezuela</option><option value="Vietnam">Vietnam</option><option value="Zambia">Zambia</option><option value="Zimbabwe">Zimbabwe</option></select>
                              </td>
                            </tr>
                          </tbody>
                        </table>
                      </div>
                      <div>
                        <table class="infusion-field-container" style="width:100%;">
                          <tbody>
                            <tr>
                              <td class="infusion-field-label-container">
                                <label for="inf_custom_Message">Message</label>
                              </td>
                              <td class="infusion-field-input-container" style="width:200px;">
                                <textarea cols="24" id="inf_custom_Message" name="inf_custom_Message" rows="5">
                                    </textarea>
                              </td>
                            </tr>
                          </tbody>
                        </table>
                      </div>
                      <div class="infusion-submit">
                        <input type="submit" value="Submit" />
                      </div>
                    </form>
                  </td>
                </tr>
              </tbody>
            </table>
          </td>
        </tr>
      </tbody>
    </table>
  </div>

</div>

And here's my CSS:

.beta-base .preheader, .beta-base .header, .beta-base .sidebar, .beta-base .body, .beta-base .footer, #mainContent {
    text-align: left;
}
.beta-base .preheader, .beta-base .header, .beta-base .body, .beta-base .sidebar, .beta-base .leftSidebar, .beta-base .rightSidebar, .beta-base .footer {
    margin: 0;
    padding: 0;
    border: none;
    white-space: normal;
    line-height: normal;
}
.beta-base .title, .beta-base .subtitle, .beta-base .text, .beta-base img {
    margin: 0;
    padding: 0;
    background: none;
    border: none;
    white-space: normal;
    line-height: normal;
}
.beta-base .bodyContainer td.preheader{
    padding: 10px 0;
}
.beta-base .bodyContainer td.header {
    padding: 0;
    height: 30px;
}
.beta-base .bodyContainer td.body, .beta-base .bodyContainer td.footer,
.beta-base .bodyContainer td.sidebar, .beta-base .bodyContainer td.leftSidebar, .beta-base .bodyContainer td.rightSidebar {
    padding: 20px;
}
.beta-base .bodyContainer td.header p, .beta-base .bodyContainer td.preheader p, .beta-base .bodyContainer td.body p,
.beta-base .bodyContainer td.footer p, .beta-base .bodyContainer td.sidebar p,
.beta-base .bodyContainer td.leftSidebar p, .beta-base .bodyContainer td.rightSidebar p {
    margin: 0;
    color: inherit;
}
.beta-base .bodyContainer td.header div.title, .beta-base .bodyContainer td.preheader div.title, .beta-base .bodyContainer td.body div.title,
.beta-base .bodyContainer td.footer div.title, .beta-base .bodyContainer td.sidebar div.title,
.beta-base .bodyContainer td.leftSidebar div.title, .beta-base .bodyContainer td.rightSidebar div.title,
.beta-base .bodyContainer td.header div.subtitle, .beta-base .bodyContainer td.preheader div.subtitle, .beta-base .bodyContainer td.body div.subtitle,
.beta-base .bodyContainer td.footer div.subtitle, .beta-base .bodyContainer td.sidebar div.subtitle,
.beta-base .bodyContainer td.leftSidebar div.subtitle, .beta-base .bodyContainer td.rightSidebar div.subtitle,
.beta-base .bodyContainer td.header div.text, .beta-base .bodyContainer td.preheader div.text, .beta-base .bodyContainer td.body div.text, .beta-base .bodyContainer td.body div.text div,
.beta-base .bodyContainer td.footer div.text, .beta-base .bodyContainer td.sidebar div.text,
.beta-base .bodyContainer td.leftSidebar div.text, .beta-base .bodyContainer td.rightSidebar div.text {
    overflow: auto;
}
.beta-base .optout {
    margin-bottom: 10px;
    margin-top: 10px;
}
div.infusion-captcha {
    width: 220px;
    padding: 10px;
}
div.infusion-captcha input, div.infusion-captcha select, div.infusion-captcha textarea {
    width: 95%;
    display: inline-block;
    vertical-align: middle;
}
table.infusion-field-container td.infusion-field-input-container input[type='text'],
table.infusion-field-container td.infusion-field-input-container input[type='password'],
table.infusion-field-container td.infusion-field-input-container textarea {
    width: 98%; /* must be 98% to make the snippet-menu line up due to border width */
    margin: 0;
}
table.infusion-field-container td.infusion-field-input-container select {
    width: 101%;
    *width: 102%; /* this one for IE */
    margin: 0;
}
table.infusion-field-container td.infusion-field-label-container {
    padding-right: 5px;
}
td.header .image-snippet img {
    vertical-align: bottom;
}
#webformErrors {
    color: #990000;
    font-size: 14px;
}
html, body {
    margin: 0;
    padding: 0;
    height: 100%;
}
.infusion-form {
    margin: 0;
    height: 100%;
}
.infusion-option {
    display: block;
    text-align: left;
}
</style>
<style type="text/css">
.beta-font-b h1, .beta-font-b h2, .beta-font-b h3, .beta-font-b h4, .beta-font-b h5, .beta-font-b h6 {
    font-family: arial,sans-serif;
}
.beta-font-b h1 {font-size: 24px;}
.beta-font-b h2 {font-size: 20px;}
.beta-font-b h3 {font-size: 14px;}
.beta-font-b h4 {font-size: 12px;}
.beta-font-b h5 {font-size: 10px;}
.beta-font-b h6 {font-size: 8px;}
.beta-font-b address {font-style: italic;}
.beta-font-b pre {font-family: Courier New, monospace;}
.beta-font-b .title, .beta-font-b .title p {
    font-size: 20px;
    font-weight: bold;
    font-family: arial,sans-serif;
}
.beta-font-b .subtitle, .beta-font-b .subtitle p {
    font-size: 11px;
    font-weight: normal;
    font-family: arial,sans-serif;
}
.beta-font-b .text, .beta-font-b p {
    font-size: 12px;
    font-family: arial,sans-serif;
}
.beta-font-b .preheader .text, .beta-font-b .preheader .text p {
    font-size: 11px;
    font-family: arial,sans-serif;
}
.beta-font-b .footer a {
    font-size: 11px;
    font-family: arial,sans-serif;
}
.beta-font-b .footer .text {
    font-size: 10px;
    font-family: verdana,sans-serif;
}
.beta-font-b .sidebar .title, .beta-font-b .leftSidebar .title, .beta-font-b .rightSidebar .title {
    font-size: 15px;
    font-weight: bold;
    font-family: arial,sans-serif;
}
.beta-font-b .sidebar .subtitle, .beta-font-b .leftSidebar .subtitle, .beta-font-b .rightSidebar .subtitle {
    font-size: 12px;
    font-family: arial, sans-serif;
}
.beta-font-b .sidebar .text, .beta-font-b .sidebar .text p, .beta-font-b .leftSidebar .text, .beta-font-b .rightSidebar .text {
    font-size: 11px;
    font-family: arial, sans-serif;
}
.infusion-field-label-container {
    font-size: 14px;
    font-family: arial,sans-serif;
}
.infusion-field-input-container {
    color: #000000;
    font-size: 12px;
}
.infusion-option label {
    color: #000000;
    font-size: 14px;
    font-family: arial,sans-serif;
}
</style>
<style type="text/css">
.default .background{
background-color:#ffffff;
;
}
.default .title{
color:#000000;
;
}
.default .subtitle{
color:#000000;
;
}
.default .text{
color:#000000;
;
}
.default a{
color:#0645ad;
;
}
.default .background .preheader .text{
color:#1a242e;
;
}
.default .background .preheader a{
color:#0645ad;
;
}
.default .header{
background-color:#ffffff;
;
}
.default .header .title{
color:#000000;
;
}
.default .header .subtitle{
color:#000000;
;
}
.default .header .text{
color:#000000;
;
}
.default .header .a{
color:#157DB8;
;
}
.default .hero{
background-color:#025C8D;
;
}
.default .hero .title{
color:#FFFFFF;
;
}
.default .hero .subtitle{
color:#FFFFFF;
;
}
.default .hero .text{
color:#FFFFFF;
;
}
.default .hero .a{
color:#157DB8;
;
}
.default .quote{
background-color:#013B5A;
;
}
.default .quote:after{
border-color:#013B5A transparent transparent transparent;
;
}
.default .quote .title{
color:#FFFFFF;
;
}
.default .quote .subtitle{
color:#FFFFFF;
;
}
.default .quote .text{
color:#FFFFFF;
;
}
.default .quote .a{
color:#157DB8;
;
}
.default .body{
background-color:#ffffff;
;
}
.default .main{
background-color:#FFFFFF;
;
}
.default .main .title{
color:#000000;
;
}
.default .main .subtitle{
color:#000000;
;
}
.default .main .text{
color:#000000;
;
}
.default .main .a{
color:#157DB8;
;
}
.default .sidebar{
background-color:#ffffff;
;
}
.default .sidebar .title{
color:#000000;
;
}
.default .sidebar .subtitle{
color:#000000;
;
}
.default .sidebar .text{
color:#000000;
;
}
.default .sidebar .a{
color:#157DB8;
;
}
.default .leftSidebar{
background-color:#ffffff;
;
}
.default .leftSidebar .title{
color:#f15c25;
;
}
.default .leftSidebar .subtitle{
color:#669940;
;
}
.default .rightSidebar{
background-color:#ffffff;
;
}
.default .rightSidebar .title{
color:#f15c25;
;
}
.default .rightSidebar .subtitle{
color:#669940;
;
}
.default .footer{
background-color:#ffffff;
;
}
.default .footer .text{
color:#0d0d0d;
;
}
.default .footer .title{
color:#000000;
;
}
.default .footer a{
color:#1b3bde;
;
}
.default .footer .subtitle{
color:#000000;
;
}
.default .infusion-field-label-container{
font-size:14px;
;
}
.default .infusion-field-label-container{
font-family:Arial;
;
}
.default .infusion-field-label-container{
color:#000000;
;
}
.default .infusion-field-input{
font-size:14px;
;
}
.default .infusion-option label{
font-size:14px;
;
}
.default .infusion-option label{
font-family:Arial;
;
}
.default .infusion-option label{
color:#000000;
;
}
.default .webFormBodyContainer{
border-width:0px;
;
}
.default .webFormBodyContainer{
border-style:Hidden;
;
}
.default .webFormBodyContainer{
border-color:#000000;
;
}
</style>
<style type="text/css">
.infusion-field-label-container {
text-align:Left;
}
.infusion-field-input-container {
width:200px;
}
.infusion-field-label-container {
vertical-align:Middle;
}
.bodyContainer {
width:425px;
}

I was wondering how can make my form responsive.

Which CSS should I fix to do so.

Any idea? It would be helpful if you can also show me some JSFIDDLE codes.

Thank you in advance.

Answer 1

As I am not allowed to comment, I am trying to explain things in answer mode.

1. Remove all your width property, which are in "px", either it's written with style attribute on element OR that element's CSS.
2. User width in Percentage(%) instead of Pixels. There may be scenarios where you like to set a width (like input), use min-width there.
3. Use media queries to set change your width(which are in % now) based on your viewport. You may require to stack your elements(like label in one line and input box in another line) on smaller viewport, which can be done by using media queries

Open to help futher.

Answer 2

I have used your example in fiddle and my answer is you can check on https://jsfiddle.net/7qbbf444/ enter code here.

Just remove the in-line style tag of width:100% and remove the width of body container.

Hope this answer helps.