body, html {
  height: 100%;
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background: #0f2027;
  background: linear-gradient(to right, #2c5364, #203a43, #0f2027);
  overflow: hidden;
}

#particles-js {
  position: fixed;
  width: 100%;
  height: 100%;
  z-index: 0;
}

.login-box {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 320px;
  padding: 40px;
  transform: translate(-50%, -50%);
  background: rgba(255, 255, 255, 0.1);
  border-radius: 15px;
  box-shadow: 0 0 25px rgba(0, 0, 0, 0.5);
  z-index: 1;
  backdrop-filter: blur(10px);
  text-align: center;
}

.login-box h2 {
  margin: 0 0 30px;
  color: #fff;
}

.user-box {
  position: relative;
  margin-bottom: 30px;
}

.user-box input {
  width: 100%;
  padding: 10px 0;
  background: transparent;
  border: none;
  border-bottom: 1px solid #fff;
  outline: none;
  color: #fff;
  font-size: 16px;
}

.user-box label {
  position: absolute;
  top: 10px;
  left: 0;
  color: #ccc;
  pointer-events: none;
  transition: 0.3s ease all;
}

.user-box input:focus ~ label,
.user-box input:valid ~ label {
  top: -15px;
  font-size: 12px;
  color: #03e9f4;
}

.login-button {
  background: #03e9f4;
  color: #000;
  padding: 10px;
  border: none;
  width: 100%;
  border-radius: 5px;
  cursor: pointer;
  font-weight: bold;
  transition: background 0.3s ease;
}

.login-button:hover {
  background: #00bcd4;
}

.error {
  color: red;
  margin-top: 10px;
  font-size: 14px;
}

/* Responsive */
@media (max-width: 400px) {
  .login-box {
    width: 90%;
    padding: 30px;
  }
}