:root {
  --bg: #0f1117;
  --card-bg: #161b22;
  --text: #e2e8f0;
  --text-dim: #94a3b8;
  --accent: #3b82f6;
  --accent-glow: #60a5fa;
  --border: #334155;
  --red: #f87171;
}

[data-theme="dark"] {
  background: var(--bg);
  color: var(--text);
}

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

body {
  font-family: 'Inter', system-ui, sans-serif;
  background: var(--bg);
  min-height: 100vh;
  padding: 2rem;
  line-height: 1.6;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto 3rem;
}

.logo {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -1px;
  color: var(--accent-glow);
  text-shadow: 0 0 10px rgba(59,130,246,0.5);
}

.auth button {
  margin-left: 1rem;
  padding: 0.5rem 1.2rem;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s;
}

.auth button:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}

h1 {
  text-align: center;
  font-size: 2.8rem;
  margin-bottom: 0.5rem;
  background: linear-gradient(90deg, #60a5fa, #a5b4fc);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  text-align: center;
  color: var(--text-dim);
  margin-bottom: 3rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
  max-width: 1200px;
  margin: 0 auto;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.8rem 1.5rem;
  text-decoration: none;
  color: inherit;
  transition: all 0.25s ease;
  position: relative;
  overflow: hidden;
}

.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent, rgba(59,130,246,0.08));
  opacity: 0;
  transition: opacity 0.4s;
}

.card:hover::before {
  opacity: 1;
}

.card:hover {
  transform: translateY(-6px);
  border-color: var(--accent);
  box-shadow: 0 20px 30px -10px rgba(0,0,0,0.6), 0 0 20px rgba(59,130,246,0.25);
}

.card.inactive {
  opacity: 0.55;
  filter: grayscale(0.4);
}

.card.inactive:hover {
  transform: none;
  box-shadow: none;
  border-color: var(--border);
  cursor: not-allowed;
}

.icon {
  font-size: 2.8rem;
  margin-bottom: 1rem;
  opacity: 0.9;
}

.card h3 {
  font-size: 1.35rem;
  margin-bottom: 0.6rem;
}

.card p {
  color: var(--text-dim);
  font-size: 0.95rem;
}

/* 鼠标悬停提示（title 属性已足够，但可增强） */
.card[title] {
  position: relative;
}

.card[title]:hover:after {
  content: attr(title);
  position: absolute;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%);
  background: #1e293b;
  color: white;
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.85rem;
  white-space: nowrap;
  z-index: 10;
  margin-bottom: 8px;
  border: 1px solid #334155;
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.75);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal-content {
  background: #1e293b;
  padding: 2.2rem;
  border-radius: 12px;
  width: 90%;
  max-width: 420px;
  border: 1px solid #334155;
  position: relative;
}

.close {
  position: absolute;
  right: 1.5rem;
  top: 1rem;
  font-size: 1.8rem;
  cursor: pointer;
  color: var(--text-dim);
}

.modal input, .modal button {
  width: 100%;
  padding: 0.9rem;
  margin: 0.8rem 0;
  border-radius: 6px;
  border: 1px solid #334155;
  background: #0f172a;
  color: white;
  font-size: 1rem;
}

.modal button {
  background: var(--accent);
  border: none;
  cursor: pointer;
  font-weight: 600;
}

.modal button:hover {
  background: #2563eb;
}

#sendCode {
  width: auto;
  background: #475569;
  font-size: 0.9rem;
  padding: 0.6rem 1rem;
  margin-left: 0.8rem;
}

#toggleText {
  text-align: center;
  margin-top: 1.2rem;
  color: var(--text-dim);
}

#toggleText a {
  color: var(--accent-glow);
  text-decoration: none;
}

/* 响应式 */
@media (max-width: 600px) {
  body { padding: 1.2rem; }
  h1 { font-size: 2.2rem; }
  .grid { gap: 1.2rem; }
}