body {
  background: black;
  color: #00ff88;
  font-family: monospace;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.container {
  width: 700px;
  max-width: 90%;
  padding: 40px;
  border: 1px solid #00ff88;
  box-shadow: 0 0 20px #00ff88;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

h2 {
  font-size: 32px;
  margin-bottom: 30px;
  text-align: center;
}

input {
  margin: 15px 0;
  padding: 18px;
  font-size: 18px;
  background: black;
  border: 1px solid #00ff88;
  color: #00ff88;
}

input::placeholder {
  color: #007744;
}

button {
  width: 100%;
  padding: 18px;
  font-size: 18px;
  background: #00ff88;
  border: none;
  cursor: pointer;
  margin-top: 20px;
  transition: 0.3s;
}

button:hover {
  background: #00cc66;
}

.hidden {
  display: none;
  margin-top: 30px;
  font-size: 20px;
  text-align: center;
}

.error {
  color: red;
  margin-top: 15px;
  text-align: center;
  font-size: 18px;
}

a {
  color: #00ff88;
  display: block;
  margin-top: 20px;
  font-size: 22px;
  text-decoration: none;
}
@media (max-width: 600px) {

  body {
    align-items: flex-start;
    padding: 20px 10px;
  }

  .container {
    width: 100%;
    padding: 20px;
    box-shadow: none;
    border: none;
  }

  h2 {
    font-size: 24px;
    margin-bottom: 20px;
  }
  span{
    font-size: 12px;
    display: block;
    margin-top: 20px;
    text-align: center;
  }

  input {
    padding: 14px;
    font-size: 16px;
    margin: 10px 0;
    flex-wrap: nowrap
  }

  button {
    width: 100%;
    padding: 18px;
    font-size: 18px;
    background: transparent;
    border: 2px solid #00ff88;
    color: #00ff88;
    cursor: pointer;
    margin-top: 20px;
    transition: 0.3s;
    position: relative;
    overflow: hidden;
  }

  /* эффект свечения */
  button:hover {
    background: #00ff88;
    color: black;
    box-shadow: 0 0 10px #00ff88, 0 0 30px #00ff88;
  }

  /* эффект "сканирования" */
  button::before {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(120deg, transparent, rgba(0,255,136,0.4), transparent);
    transition: 0.5s;
  }

  button:hover::before {
    left: 100%;
  }

  .hidden {
    font-size: 18px;
  }

  a {
    display: inline-block;
    margin-top: 30px;
    padding: 18px 30px;
    font-size: 20px;
    text-decoration: none;
    color: #00ff88;
    border: 2px solid #00ff88;
    position: relative;
    overflow: hidden;
    transition: 0.3s;
    letter-spacing: 2px;
  }

  /* неоновый hover */
  a:hover {
    color: black;
    background: #00ff88;
    box-shadow: 0 0 15px #00ff88, 0 0 40px #00ff88;
  }

  /* эффект "энергии" */
  a::before {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(120deg, transparent, rgba(0,255,136,0.5), transparent);
    transition: 0.6s;
  }

  a:hover::before {
    left: 100%;
  }

}