Red Asterisk directly beside placeholder in input box - forms

Question

I've done a bunch of googling, but I can't find an answer anywhere that works for me.
I'm creating a form (for the first time ever) and I need a red asterisk directly next to the placeholder text in the input boxes. Embarrassingly, this is the closest I have been able to get so far:
form {
margin: 0 auto;
background-color: #3d549a;
}
input {
font-family: avenir;
font-size: 17px;
color: #ffffff;
font-weight: 100;
border: none;
width: 400px;
padding: 15px;
border-radius: 5px;
}
textarea {
height: 5em;
resize: vertical;
font-family: avenir;
font-size: 17px;
color: #ffffff;
font-weight: 100;
border: none;
width: 860px;
padding: 15px;
border-radius: 5px;
}
.asterisk_input:after {
content: " *";
color: #e32;
position: absolute;
margin: 0px 0px 0px -20px;
font-size: 17px;
padding: 0 5px 0 0;
}
.buttonblue {
padding-left: 90px;
background-color: #31b9e9;
font-family: avenir;
font-size: 16px;
width: 300px;
height: 75px;
color: #ffffff;
padding: 0;
border: none;
border-radius: 5px;
box-shadow: 0px 5px 1px #21a1c6;
}
button {
margin-left: .5em;
}
<table width="100%" style="background-color: #3d549a" height="820px">
<tr height="250">
<td valign="bottom" align="center" width="100%" colspan="4">
<span style="font-family: avenir; font-size: 40px; color: #ffffff; font-weight: 500; line-height: 10px;">GET IN TOUCH<span/>
<hr color="#273a72" width="75" align="centre">
<span style="font-family: avenir; font-size: 15px; color: #ffffff; font-weight: 100; line-height: 10px;">1600 Pennslyvania Ave NW, Washington, DC 20500, United States of America. Tel: [phone]</span>
</td>
</tr>
<tr>
<td>
<form action="/my-handling-form-page" method="post">
<p>
<input type="text" id="name" placeholder="Your Name" style="font-family: avenir; font-weight:100; font-size: 17px; background-color: #273a72" />
<span class="asterisk_input"> </span>
<input type="email" id="mail" placeholder="Your Email" style="font-family: avenir; font-weight:100; font-size: 17px; background-color: #273a72" />
<span class="asterisk_input"> </span>
</p>
<p>
<textarea id="msg" placeholder="Your Message" style="font-family: avenir; color: #fff; font-weight:100; font-size: 17px; background-color: #273a72"></textarea>
<span class="asterisk_input"> </span>
</p>
<p>
<button class="buttonblue" type="submit">SEND MESSAGE</button>
</p>
</form>
</td>
</tr>
</table>
(I'm also having trouble centreing it ;) But one problem at a time, I suppose

Answer 1

Unfortunately, there isn't a universal way of doing this easily, but there is a way to get support for most browsers. The reason being is that you're going to need to style a placeholder, and there isn't a universal standard on how this is done. But, as long as you don't need support for older IE browsers, you should be okay with the following approach:
First, add a class named "required" or some such to the input box itself. Then, add the following tags:
.required::-webkit-input-placeholder:after {
content: " *";
color: red;
}
.required:-moz-placeholder:after {
content: " *";
color: red;
}
.required:-ms-input-placeholder:after {
content: " *";
color: red;
}

Answer 2

for align centre just add
display: table;
in .form class.