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

body {
  font-family: 'SF Pro Display', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: linear-gradient(135deg, #1a1a1a 0%, #2d3748 100%);
  min-height: 100vh;
  color: #e2e8f0;
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(45, 55, 72, 0.95);
  backdrop-filter: blur(20px);
  padding: 20px 0;
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  z-index: 1000;
}

.header-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo h1 {
  color: #f7fafc;
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

nav a {
  text-decoration: none;
  color: #a0aec0;
  padding: 10px 20px;
  border-radius: 12px;
  background: rgba(45, 55, 72, 0.6);
  border: 1px solid rgba(66, 153, 225, 0.2);
  transition: all 0.2s ease;
  font-weight: 500;
  font-size: 0.95rem;
}

nav a:hover {
  background: #4299e1;
  color: white;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(66, 153, 225, 0.4);
  border-color: #4299e1;
}

main {
  background: rgba(45, 55, 72, 0.9);
  backdrop-filter: blur(20px);
  border-radius: 20px;
  padding: 48px 40px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  border: 1px solid rgba(255, 255, 255, 0.1);
  width: 100%;
  max-width: 420px;
  margin-top: 100px;
}

form {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

label {
  color: #f7fafc;
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
}

input {
  background: rgba(26, 32, 44, 0.8);
  border: 2px solid rgba(66, 153, 225, 0.3);
  border-radius: 12px;
  padding: 16px 20px;
  font-size: 1rem;
  color: #f7fafc;
  transition: all 0.2s ease;
  font-family: inherit;
}

input:focus {
  outline: none;
  border-color: #4299e1;
  box-shadow: 0 0 0 3px rgba(66, 153, 225, 0.2);
  background: rgba(26, 32, 44, 0.9);
}

input::placeholder {
  color: #a0aec0;
}

button {
  background: linear-gradient(135deg, #4299e1 0%, #3182ce 100%);
  border: none;
  border-radius: 12px;
  padding: 18px 24px;
  font-size: 1rem;
  font-weight: 600;
  color: white;
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: inherit;
  letter-spacing: -0.01em;
  margin-top: 16px;
}

button:hover {
  background: linear-gradient(135deg, #3182ce 0%, #2c5282 100%);
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(66, 153, 225, 0.4);
}

button:active {
  transform: translateY(0);
}

/* 로딩 상태 효과 */
button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* 폼 애니메이션 */
main {
  animation: fadeInUp 0.6s ease-out;
}

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

/* 에러/성공 메시지 스타일 */
.message {
  padding: 16px 20px;
  border-radius: 12px;
  font-size: 0.95rem;
  text-align: center;
  margin-bottom: 24px;
  font-weight: 500;
  position: relative;
  animation: slideInDown 0.4s ease-out;
}

.message.error {
  background: rgba(245, 101, 101, 0.15);
  border: 1px solid rgba(245, 101, 101, 0.4);
  color: #fc8181;
  box-shadow: 0 4px 12px rgba(245, 101, 101, 0.1);
}

.message.error::before {
  content: '⚠️';
  margin-right: 8px;
}

.message.success {
  background: rgba(72, 187, 120, 0.15);
  border: 1px solid rgba(72, 187, 120, 0.4);
  color: #81c784;
  box-shadow: 0 4px 12px rgba(72, 187, 120, 0.1);
}

.message.success::before {
  content: '✅';
  margin-right: 8px;
}

/* 메시지 애니메이션 */
@keyframes slideInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* 에러 상태일 때 입력 필드 스타일 */
.form-group.error input {
  border-color: rgba(245, 101, 101, 0.6);
  background: rgba(245, 101, 101, 0.05);
}

.form-group.error input:focus {
  border-color: #fc8181;
  box-shadow: 0 0 0 3px rgba(245, 101, 101, 0.2);
}

/* 스크롤바 스타일링 */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: rgba(26, 32, 44, 0.3);
}

::-webkit-scrollbar-thumb {
  background: rgba(66, 153, 225, 0.5);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(66, 153, 225, 0.7);
}

/* 반응형 디자인 */
@media (max-width: 768px) {
  header {
    position: relative;
  }

  .header-content {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }

  main {
    margin-top: 0;
    padding: 32px 24px;
    max-width: 100%;
  }

  .logo h1 {
    font-size: 1.5rem;
  }
}

@media (max-width: 480px) {
  body {
    padding: 12px;
  }

  main {
    padding: 24px 20px;
    border-radius: 16px;
  }

  input {
    padding: 14px 16px;
  }

  button {
    padding: 16px 20px;
  }

  .logo h1 {
    font-size: 1.3rem;
  }
}