JSFiddle - React, Tailwind, and code Playground

HTML

<div id="login-window-small" class="login-modal">
  <div class="modal-head"><span>Member Sign In</span></div>
  <div class="modal-form">
    <form class="form" action="post">
      <label for="uname"><b>Username</b></label>
      <input id="username-input" type="text" placeholder="Enter Username" name="uname" required>
      <label for="psw"><b>Password</b></label>
      <input id="password-input" type="password" placeholder="Enter Password" name="psw" required>
      <label>
        <input type="checkbox" checked="checked" name="remember"> Remember me
      </label>
      <a> <span>Lost Password</span> </a>
    </form>
  </div>
  <div class="modal-social-links">
    <ul>
      <li><a href="">Fecebook</a></li>
      <li><a href="">Twitter</a></li>
      <li><a href="">Linkedin</a></li>
    </ul>
  </div>
  <div class="modal-buttons-cont close">
    <button>Close</button>
  </div>
  <div class="modal-buttons-cont signin">
    <button>Sign In</button>
  </div>
  <div class="bottom-padd">
    <div class="message-cont">
      <span></span>
    </div>
  </div>
</div>

CSS

.login-modal {
  background: white;
  box-sizing: border-box;
  --main-bg-color: rgb(70, 119, 139);
  display: grid;
  /* grid-auto-rows: minmax(20px, auto); */
  grid-auto-columns: minmax(120px, 180px);
  position: absolute;
  top: 100vh;
  left: 50%;
  transform: translate(-50%, -50%);
  overflow: hidden;
  border-radius: 7px;
  color: var(--main-bg-color);
  font-family: "Open Sans", sans-serif;
  box-shadow:inset 0px 0px 0px 1px var(--main-bg-color);
  z-index: 1999;
  
}


#login-window-small.login-modal ul {
  padding: 0;
  margin: 0;
}

#login-window-small.login-modal li {
  list-style-type: none;
  margin: .5em;
}

#login-window-small.login-modal a {
  text-decoration: none;
  color: var(--main-bg-color);
}

.modal-head {
  display: flex;
  align-items: center;
  color: white;
  position: relative;
  background-color: var(--main-bg-color);
}

.modal-head>span {
  margin-left: 1em;
}

.modal-form {
  margin-top: 1em;
}

.modal-form label {
  margin: .5em 0;
}

.modal-social-links {
  grid-column: 1/3;
  display: flex;
  margin: 0 0 2em 1em;

}

.form {
  display: flex;
  flex-direction: column;
  font-size: 16px;
  margin: 0 1em;
}

.form input[type="password"],
.form input[type="text"] {
  height: 2em;
  font-size: 16px;
  border: 1px solid #aaa;
  border-radius: 3px;
  padding-left: 5px;
}

#login-window-small .form a {
  display: flex;
  justify-content: flex-end;
  cursor: pointer;
}

#login-window-small .form a>span {
  color: rgb(250, 91, 15);
}


.modal-head {
  grid-row: 1/3;
  height: 4em;
}

.modal-head,
.modal-form {
  grid-column: 1/3;
}

.modal-buttons-cont {
  display: flex;
  justify-content: center;

}

.modal-buttons-cont button {
  border: 1px solid var(--main-bg-color);
  border-radius: .2em;
  padding: .5em 1.5em;
  font-size: 18px;
  cursor: pointer;
}

.modal-buttons-cont.close {
  grid-column: 1;
  opacity: unset;
}

.modal-buttons-cont.signin {
  grid-column: 2;
}

.modal-buttons-cont.close button {
  color: var(--main-bg-color);
 ...