* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background-color: #f4f6fc;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Static BG element */
#background {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(to right, #007bff, #00c6ff);
  z-index: -1;
  opacity: 0.15;
}

/* Main layout */
#root {
  background: white;
  padding: 2rem;
  border-radius: 12px;
  width: 90%;
  max-width: 420px;
  box-shadow: 0 0 15px rgba(0,0,0,0.1);
}

#span_sign {
  display: flex;
  justify-content: center;
  margin-bottom: 1.5rem;
}

#span_sign button {
  flex: 1;
  padding: 0.75rem;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  background-color: #eaeaea;
  color: #333;
  border-radius: 8px 8px 0 0;
  transition: background 0.3s;
}

#span_sign button.active {
  background-color: #007bff;
  color: white;
  font-weight: bold;
}

#auth_form h2 {
  text-align: center;
  margin-bottom: 1rem;
}

form {
  display: flex;
  flex-direction: column;
}

form label {
  margin-bottom: 0.25rem;
  font-weight: bold;
}

form input {
  padding: 0.5rem;
  margin-bottom: 1rem;
  border-radius: 6px;
  border: 1px solid #ccc;
}

form button[type="submit"] {
  padding: 0.75rem;
  border: none;
  border-radius: 6px;
  background-color: #007bff;
  color: white;
  cursor: pointer;
  font-size: 1rem;
}

#footer {
  margin-top: 2rem;
  text-align: center;
  font-size: 0.9rem;
  color: #666;
}