не работает input в попап окне, как исправить?

.popup {
  position: fixed;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.8);
  top: 0;
  left: 0;
  opacity: 0;
  visibility: hidden;
}

.popup:target {
  opacity: 1;
  visibility: visible;
}

.popup_body {
  min-width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 30px 10px;
}

.popup_content {
  background-color: #fff;
  color: #000;
  max-width: 800px;
  padding: 30px;
  color: black;
  position: relative;
}

.popup_close {
  position: absolute;
  right: 10px;
  top: 10px;
  font-size: 20px;
}

.popup_title {
  font-size: 40px;
  margin: 0px 0px 1em 0px;
}

.popup_text {}

<div class="popup" id="popup">
  <div class="popup_body">
    <div class="popup_content">
      <form method="post" class="method_registration">
        <h1 class="h1Form">Регистрация</h1>
        <p class="formP"><input placeholder="логин" class="form" type="fname" name="fname" required id="fnameInput"></p>
        <p class="formP"><input placeholder="email" class="form" type="lname" name="lname" required id="lname"></p>
        <p class="formP"><input placeholder="пароль" class="form" type="password" required name="password_1" id="password_1"></p>
        <p class="formP"><input placeholder="пароль" class="form" type="password" required name="password_2" id="password_2"></p>
        <input class="inputForm" value="Регистрация" type="button" onclick="validate()">
        <p><input id="checkbox" type="checkbox" name="checkbox"><span>Я не робот</span>
          <p id="information"></p>
      </form>
      <a href="#" class="popup_close">x</a>
    </div>
  </div>
</div>