HTML

• CSS Link file:

   <link rel="stylesheet" type="text/css" href="index.css">

• Rediect to another page after submit action:

   <form action="result.php" method="post" id="codered" runat="vdaemon">

• Apply Regex to input:
  

Here only 8 numbers input can be entered
It should start from 7, ex:

7xxxxxxx
71234456

    <div>
         <lable for="sr">SR Number</lable>
         <input type="text" name="sr" id="SR" placeholder="SR#" maxlength="8" pattern="[7][0-9]{7,}" required title="Enter a valid Case Number">
    </div>

• Code not sure:

          <input type="hidden" name="formID" value="srinfo" />
          <input type="hidden" name="redirect_to" value="view.php" />

• Send Email Link:

<a href="mailto:Amandeep Singh<aman@test.com>?Subject=Application%20Issue%20Report&body=Hi,%0D%0A%0D%0APlease find the below Test application issue report:&cc=Sender2 <sender2@test.com>" target="_top">Here</a>

• Adding Logo:

<header>
<h1>
<img src="logo.png" alt="logo" align="right" height="40" width="120"/>
Test Application
</h1>
</header>

• Permitting email from a specific domain only:

            <div>
                <lable for="email">Engineer Email</lable>
                <input type="text" name="email" id="email" placeholder="username@domain.com" maxLength="64" pattern=".+@domain.com" required title="Please enter a valid Email ID">
            </div>

• Adding Datalist for default options:

           <div>
                <lable for="ProductVersion">Product Version </lable>
                <input type="text" name="ProductVersion" id="ProductVersion" placeholder="My Product Version" list="defaultProduct">
                <datalist id="defaultProduct">
                    <option value="Version 1">
                    <option value="Version 2">
                </datalist>
            </div>

• Input at least 3 characters:

            <div>
                <lable for="Geo">Account Country</lable>
                <input type="text" name="Geo" id="Geo" placeholder="Customer's Country" pattern=".{3,}" required title="Enter Country Name">
            </div>