:root {
  --bg-color: #1f2937;
  --bg-gradient: linear-gradient(135deg, #4f46e5, #7c3aed, #a855f7);
  --text-color: #e5e7eb;
  --box-color: rgba(17, 24, 39, 0.6);
  --border-color: #4b5563;
  --btn-color: #a855f7;
  --btn-hover: #7c3aed;
  --shadow-color: rgba(168, 85, 247, 0.4);
}

.light-mode {
  --bg-color: #f9fafb;
  --bg-gradient: linear-gradient(180deg, #ffffff 0%, #f3f4f6 100%);
  --text-color: #1f2937;
  --box-color: #ffffff;
  --border-color: #d1d5db;
  --btn-color: #6366f1;
  --btn-hover: #4f46e5;
  --shadow-color: rgba(99, 102, 241, 0.4);
}

body {
  margin: 0;
  font-family: Pretendard, -apple-system, BlinkMacSystemFont, system-ui, Roboto,
    "Helvetica Neue", Segoe UI, Apple SD Gothic Neo, Noto Sans KR, Malgun Gothic,
    sans-serif;
  background: var(--bg-gradient);
  color: var(--text-color);
  animation: fadeIn 0.8s ease forwards;
  min-height: 100vh;
}

@keyframes fadeIn {
  to {
    opacity: 1;
  }
}

header {
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-color);
  background: transparent;
}

.header-actions button {
  margin-left: 0.5rem;
}

.mode-toggle {
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-color);
  border-radius: 0.5rem;
  cursor: pointer;
  padding: 0.4rem 0.6rem;
  transition: all 0.25s ease;
}
.mode-toggle:hover {
  border-color: var(--btn-color);
  color: var(--btn-color);
}

.logout-btn {
  background: #ef4444;
  color: white;
  border: none;
  border-radius: 0.5rem;
  padding: 0.4rem 0.8rem;
  font-size: 0.85rem;
  cursor: pointer;
  transition: background-color 0.25s ease;
}
.logout-btn:hover {
  background: #b91c1c;
}

main {
  max-width: 800px;
  margin: 2rem auto;
  background: var(--box-color);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: 0 10px 25px var(--shadow-color);
  transition: background 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

main h2 {
  text-align: center;
  font-size: 1.75rem;
  margin-bottom: 1.5rem;
  color: var(--text-color);
}

.input-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.input-group input {
  flex: 1;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  background: var(--bg-color);
  color: var(--text-color);
  transition: background 0.3s ease, border-color 0.3s ease;
}

.input-group input::placeholder {
  color: var(--border-color);
}

.input-group input:focus {
  outline: none;
  border-color: var(--btn-color);
  background: var(--box-color);
  box-shadow: 0 0 8px var(--btn-color);
}

.input-group button {
  background: var(--btn-color);
  color: white;
  border: none;
  border-radius: 0.75rem;
  padding: 0.6rem 1rem;
  cursor: pointer;
  font-weight: 700;
  transition: background-color 0.3s ease, transform 0.3s ease;
}

.input-group button:hover {
  background: var(--btn-hover);
  transform: scale(1.05);
}

.password-section {
  margin-bottom: 2rem;
}

.password-section h3 {
  font-size: 1.2rem;
  margin-bottom: 0.75rem;
  color: var(--text-color);
}

.pw-inputs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}

.pw-inputs input {
  flex: 1;
  padding: 0.6rem;
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  background: var(--bg-color);
  color: var(--text-color);
  transition: background 0.3s ease, border-color 0.3s ease;
}

.password-section button {
  background: var(--btn-color);
  color: white;
  border: none;
  border-radius: 0.75rem;
  padding: 0.6rem 1rem;
  cursor: pointer;
  font-weight: 700;
  transition: background-color 0.3s ease;
}

.password-section button:hover {
  background: var(--btn-hover);
}

.cards-section h3 {
  font-size: 1.2rem;
  margin-bottom: 0.75rem;
  color: var(--text-color);
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1rem;
}

.card {
  background: var(--box-color);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1rem;
  text-align: center;
  cursor: pointer;
  transition: transform 0.3s ease, background 0.3s ease;
  color: var(--text-color);
  box-shadow: 0 2px 8px var(--shadow-color);
}

.card:hover {
  transform: translateY(-5px);
  background: rgba(124, 58, 247, 0.1);
}

.card h4 {
  margin: 0.5rem 0;
  font-size: 1.1rem;
}

.card p {
  font-size: 0.9rem;
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.9rem;
  color: #8b8b8b;
}

/* 모바일 반응형 */
@media (max-width: 768px) {
  main {
    margin: 1rem;
    padding: 1rem;
  }
  .cards {
    grid-template-columns: 1fr;
  }
}

/* 아주 작은 화면 대응 */
@media (max-width: 480px) {
  main h2 {
    font-size: 1.5rem;
  }
  .cards-section h3 {
    font-size: 1rem;
  }
  .card h4 {
    font-size: 1rem;
  }
  .card p {
    font-size: 0.85rem;
  }
}