:root {
  --bg-color: #0a0a1a;
  --text-color: #ffffff;
  --feature-bg: rgba(255, 255, 255, 0.05);
  --feature-border: rgba(255, 255, 255, 0.1);
}
body.light-mode {
  --bg-color: #f3f4f6;
  --text-color: #111111;
  --feature-bg: rgba(0, 0, 0, 0.05);
  --feature-border: rgba(0, 0, 0, 0.1);
}
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Arial', sans-serif;
}
body {
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  overflow-x: hidden;
  transition: background-color 0.4s, color 0.4s;
  background-image: radial-gradient(circle at 20% 30%, rgba(33, 82, 156, 0.3) 0%, transparent 50%),
    radial-gradient(circle at 80% 70%, rgba(97, 24, 128, 0.3) 0%, transparent 50%);
}
/* top controls */
.top-controls {
  position: absolute;
  top: 20px;
  right: 20px;
  display: flex;
  gap: 1rem;
  z-index: 1000;
}
.toggle-button,
.auth-button {
  background: transparent;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-color);
}
.auth-button {
  font-size: 1rem;
  padding: 0.5rem 1rem;
  background: linear-gradient(90deg, #6a11cb 0%, #2575fc 100%);
  color: #fff;
  border-radius: 20px;
  font-weight: bold;
}
.auth-button:hover {
  background: linear-gradient(90deg, #2575fc 0%, #6a11cb 100%);
}
/* hero */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 2rem;
  position: relative;
  overflow: hidden;
}
.stars {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
}
.star {
  position: absolute;
  background: white;
  border-radius: 50%;
  animation: twinkle var(--duration) infinite ease-in-out;
}
@keyframes twinkle {
  0%,100% { opacity: 0.2; }
  50% { opacity: 1; }
}
.title {
  font-size: clamp(2.5rem, 8vw, 5rem);
  font-weight: 900;
  margin-bottom: 1rem;
  text-transform: uppercase;
  background: linear-gradient(90deg, #6a11cb 0%, #2575fc 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  animation: cosmicGlow 4s infinite alternate, fadeIn 2s ease-out forwards;
  opacity: 0;
}
@keyframes cosmicGlow {
  0% { text-shadow: 0 0 10px rgba(106, 17, 203, 0.5); }
  100% { text-shadow: 0 0 20px rgba(106, 17, 203, 0.8), 0 0 30px rgba(37, 117, 252, 0.6); }
}
@keyframes fadeIn {
  0% { transform: translateY(20px); opacity: 0; }
  100% { transform: translateY(0); opacity: 1; }
}
.subtitle {
  font-size: 1.5rem;
  margin-bottom: 2rem;
  max-width: 700px;
  opacity: 0;
  animation: fadeIn 2.5s ease-out 0.5s forwards;
}
.cta-button {
  display: inline-block;
  padding: 1rem 2rem;
  background: linear-gradient(90deg, #6a11cb 0%, #2575fc 100%);
  color: #fff;
  text-decoration: none;
  border-radius: 50px;
  font-weight: bold;
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  position: relative;
  overflow: hidden;
  z-index: 1;
  animation: fadeIn 3s ease-out 1s forwards;
  opacity: 0;
}
.cta-button:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 20px rgba(37, 117, 252, 0.3);
}
.cta-button::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, #2575fc 0%, #6a11cb 100%);
  z-index: -1;
  opacity: 0;
  transition: opacity 0.3s ease;
}
.cta-button:hover::before {
  opacity: 1;
}
/* features */
.features {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 2rem;
  margin: 3rem 0;
  opacity: 0;
  animation: fadeIn 3s ease-out 1.5s forwards;
}
.feature-card {
  background: var(--feature-bg);
  border: 1px solid var(--feature-border);
  border-radius: 15px;
  padding: 2rem;
  width: 300px;
  backdrop-filter: blur(10px);
  transition: transform 0.3s ease;
  animation: floatCard 5s ease-in-out infinite alternate;
}
.feature-card:hover {
  transform: translateY(-10px);
}
@keyframes floatCard {
  from { transform: translateY(0); }
  to { transform: translateY(-8px); }
}
.feature-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: #6a11cb;
}
.feature-title {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}
.feature-desc {
  opacity: 0.8;
}
footer {
  text-align: center;
  padding: 2rem;
  opacity: 0.7;
  font-size: 0.9rem;
}
@media (max-width: 768px) {
  .features {
    flex-direction: column;
    align-items: center;
  }
}
/* Modal */
.modal {
  position: fixed;
  inset: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  background: rgba(0,0,0,0.6);
  visibility: hidden;
  opacity: 0;
  transition: opacity 0.4s ease, visibility 0.4s;
}
.modal.active {
  visibility: visible;
  opacity: 1;
}
.modal-content {
  background: var(--bg-color);
  color: var(--text-color);
  padding: 2rem;
  border-radius: 20px;
  width: 90%;
  max-width: 450px;
  animation: slideDown 0.6s ease forwards;
}
@keyframes slideDown {
  0% { transform: translateY(-30px); opacity: 0; }
  100% { transform: translateY(0); opacity: 1; }
}
.modal-content h2 {
  margin-bottom: 1rem;
  font-size: 1.8rem;
}
.form-group {
  display: flex;
  flex-direction: column;
  margin-bottom: 1rem;
}
.form-group label {
  margin-bottom: 0.3rem;
  font-weight: bold;
}
.form-group input,
.form-group textarea {
  padding: 0.7rem;
  border-radius: 8px;
  border: 1px solid var(--feature-border);
  background: var(--feature-bg);
  color: var(--text-color);
}
.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--text-color);
  opacity: 0.6;
}
.submit-btn {
  margin-top: 1rem;
  padding: 0.7rem 1.5rem;
  border: none;
  border-radius: 25px;
  background: linear-gradient(90deg, #6a11cb 0%, #2575fc 100%);
  color: #fff;
  font-weight: bold;
  cursor: pointer;
  transition: background 0.3s;
}
.submit-btn:hover {
  background: linear-gradient(90deg, #2575fc 0%, #6a11cb 100%);
}
.close-btn {
  position: absolute;
  top: 15px;
  right: 20px;
  font-size: 1.5rem;
  background: none;
  border: none;
  color: var(--text-color);
  cursor: pointer;
}