* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    'Helvetica Neue', Arial, sans-serif;
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
  background-size: 200% 200%;
  animation: gradientShift 15s ease infinite;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  position: relative;
}

@keyframes gradientShift {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}

/* 배경 파티클 효과 */
.particles {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  z-index: 0;
}

.particle {
  position: absolute;
  width: 2px;
  height: 2px;
  background: rgba(96, 165, 250, 0.5);
  border-radius: 50%;
  animation: float 15s infinite ease-in-out;
}

@keyframes float {
  0%,
  100% {
    transform: translateY(0) translateX(0);
    opacity: 0;
  }
  10% {
    opacity: 1;
  }
  90% {
    opacity: 1;
  }
  100% {
    transform: translateY(-100vh) translateX(100px);
    opacity: 0;
  }
}

.container {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 40px 20px;
  animation: fadeIn 1s ease-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.logo {
  width: 120px;
  height: 120px;
  margin: 0 auto 40px;
  animation: float-logo 3s ease-in-out infinite;
  filter: drop-shadow(0 0 20px rgba(96, 165, 250, 0.6));
}

@keyframes float-logo {
  0%,
  100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-10px);
  }
}

.logo img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

h1 {
  font-size: 5rem;
  font-weight: 900;
  background: linear-gradient(135deg, #3b82f6 0%, #60a5fa 50%, #818cf8 100%);
  background-size: 200% 200%;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 20px;
  animation: titleGlow 3s ease-in-out infinite, gradientShift 5s ease infinite;
  letter-spacing: -0.02em;
  text-shadow: 0 0 40px rgba(96, 165, 250, 0.5);
}

@keyframes titleGlow {
  0%,
  100% {
    filter: drop-shadow(0 0 20px rgba(96, 165, 250, 0.6));
  }
  50% {
    filter: drop-shadow(0 0 40px rgba(96, 165, 250, 0.9));
  }
}

.subtitle {
  font-size: 1.25rem;
  color: #94a3b8;
  margin-bottom: 60px;
  animation: fadeIn 1s ease-out 0.3s both;
}

.enter-button {
  display: inline-block;
  padding: 20px 60px;
  font-size: 1.5rem;
  font-weight: 700;
  color: #ffffff;
  background: linear-gradient(135deg, #2563eb 0%, #3b82f6 50%, #60a5fa 100%);
  background-size: 200% 200%;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.3s ease;
  animation: fadeIn 1s ease-out 0.6s both;
  position: relative;
  overflow: hidden;
  box-shadow: 0 10px 30px rgba(37, 99, 235, 0.4);
}

.enter-button::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.3),
    transparent
  );
  transition: left 0.5s;
}

.enter-button:hover::before {
  left: 100%;
}

.enter-button:hover {
  transform: translateY(-3px) scale(1.05);
  box-shadow: 0 15px 40px rgba(37, 99, 235, 0.6),
    0 0 60px rgba(96, 165, 250, 0.5);
  background-position: 100% 50%;
}

.enter-button:active {
  transform: translateY(-1px) scale(1.02);
}

/* 반응형 디자인 */
@media (max-width: 768px) {
  h1 {
    font-size: 3rem;
  }

  .subtitle {
    font-size: 1rem;
  }

  .enter-button {
    padding: 16px 48px;
    font-size: 1.25rem;
  }

  .logo {
    width: 80px;
    height: 80px;
  }
}

@media (max-width: 480px) {
  h1 {
    font-size: 2.5rem;
  }

  .enter-button {
    padding: 14px 40px;
    font-size: 1.125rem;
  }
}