<div class="container">
  <form action="/action_page.php" method="post">
    <div class="row">
        <div class="col-70">
           <input type="text" id="name" name="Name" placeholder="Name*" required>
        </div>
    </div>
    <div class="row">
        <div class="col-70">
          <input type="email" id="email" name="email "placeholder="Email*" required> 
        </div>
    </div>
    <div clas="row">
      <div class="col-70">
        <input type="text" id="subject" name="subject" placeholder="Subject" > 
      </div>
    </div>
    <div class="row">
      <div class="col-70">
        <textarea id="message" placeholder="Message" ></textarea>
      </div>
    </div>
    <div class="row">
      <div class="col-70">
        <input type="submit" id="submit" value="Send Message">
      </div>
    </div>
  </form>
</div>  

.container {
  border-radius: 5px; 
  background-color: #d66ff66;
  padding: 2px;  
}

.row:after {
  content: "";
  display: table;
  clear : both;
}

.col-70{
  margin-left: 5em;
  margin-top: 10px;
  padding: 10px;
  width: 70%;
}

input[type=text], [type=email] { 
  width: 100%;
  padding: 12px;
  border: hidden;
  font-size: 18px;
  font-family: calibri;
  border-bottom: 2px solid grey;
  outline: none;
  box-sizing: border-box;
  resize: vertical;
}

input:focus {
  font-style: italic;
  border-bottom: 2px solid black;
}

textarea{
 width: 100%;
  font-style:calibri; 
  padding: 12px;
  border: hidden;
  font-size: 18px;
  font-family: calibri;
  border-bottom: 2px solid grey;
  outline: none;
  height: 100px;
  resize: none;
}

textarea:focus  {
  font-style: italic;
  border-bottom: 2px solid black;
}

input[type=submit] {
  border: 2px solid grey;
  padding: 12px 12px 10px 12px;
  font-size: 18px;
  font-family: calibri;
  background-color: white;
  font-weight: 700;
  float: right;
  color: grey;
  text-transform: uppercase;
  transition: all 0.35s ease-in-out;
}

input[type=submit]:hover {
  color: black;
  padding: 12px 56px 10px 56px;
  ouline: none;
  border: 2px solid black;
  letter-spacing: 0px;
  
}

@media screen and (max-width: 600px) {
    .row, .col-70, input[type=submit] {
        width: 100%;
        margin-top: 0;
    }
}