:root {
  --font-family: "Segoe UI", "PingFang SC", sans-serif;
  --text-primary: #1f2937;
  --text-secondary: #374151;
  --text-muted: #6b7280;
  --bg-app: transparent;
  --bg-nav: rgba(255, 255, 255, 0.65);
  --bg-card: rgba(255, 255, 255, 0.7);
  --bg-inner-item: rgba(255, 255, 255, 0.6);
  --primary-color: #3b82f6;
  --primary-color-text: white;
  --transition-duration: 300ms;
  --transition-timing: ease-out;
}

body.dark {
  --text-primary: #f9fafb;
  --text-secondary: #e5e7eb;
  --text-muted: #9ca3af;
  --bg-nav: rgba(20, 20, 22, 0.65);
  --bg-card: rgba(30, 30, 32, 0.7);
  --bg-inner-item: rgba(40, 40, 42, 0.6);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: var(--font-family);
}

html {
  scroll-behavior: smooth;
}

body {
  height: 100vh;
  overflow: auto;
  color: var(--text-primary);
  background-color: skyblue; /* fallback for bg layer */
  transition: color var(--transition-duration) var(--transition-timing), background-color var(--transition-duration) var(--transition-timing);
}

/* 背景 */
#bg-layer {
  position: fixed;
  inset: 0;
  background-size: cover;
  background-position: center;
  z-index: -1;
  transition: opacity 800ms ease;
  background-color: skyblue;
}

/* 主体 */
.app {
  min-height: 100vh;
  padding: 24px;
  background-color: var(--bg-app);
}

/* 导航栏 */
.nav {
  position: sticky;
  top: 24px; /* 顶部偏移 */
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-nav);
  border-radius: 18px;
  padding: 14px 24px;
  margin-bottom: 24px;
  transition: background-color var(--transition-duration) var(--transition-timing), 
              box-shadow var(--transition-duration) var(--transition-timing),
              transform 400ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.nav.sticky {
    box-shadow: 0 8px 20px rgba(0,0,0,0.1);
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
}

.logo img {
  width: 32px;
  height: 32px;
  border-radius: 50%;
}

.menu {
  display: flex;
}

.menu a {
  margin: 0 12px;
  color: var(--text-secondary);
  text-decoration: none;
  position: relative;
  transition: color var(--transition-duration) var(--transition-timing);
}

.menu a:hover {
  color: var(--primary-color);
}

.menu a.active {
  color: var(--primary-color);
  font-weight: 600;
}

.theme-btn {
  cursor: pointer;
  user-select: none;
  transition: transform 200ms ease-out;
}
.theme-btn:active {
  transform: scale(0.9);
}


/* 内容 */
.content {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

/* 卡片 */
.card {
  background: var(--bg-card);
  border-radius: 22px;
  padding: 22px;
  border: 2px solid transparent;
  transition: background-color var(--transition-duration) var(--transition-timing), border-color var(--transition-duration) var(--transition-timing);
}
.card:hover {
    border-color: #add8ee;
}

.card h2 {
  margin-bottom: 14px;
  font-size: 18px;
}

/* IP */
.ip-box {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--bg-inner-item);
  padding: 14px 18px;
  border-radius: 14px;
  transition: background-color var(--transition-duration) var(--transition-timing);
}

.ip-box button {
  border: none;
  background: var(--primary-color);
  color: var(--primary-color-text);
  padding: 8px 16px;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 500;
  transition: transform var(--transition-duration) var(--transition-timing), background-color var(--transition-duration) var(--transition-timing);
}

.ip-box button:hover {
  transform: scale(1.05);
}
.ip-box button:active {
  transform: scale(0.98);
}


/* 客户端 */
.client-list {
  display: flex;
  gap: 20px;
}

.client-btn {
  flex: 1;
  text-align: center;
  padding: 26px;
  border-radius: 18px;
  background: var(--bg-inner-item);
  cursor: pointer;
  transition: transform var(--transition-duration) var(--transition-timing), background-color var(--transition-duration) var(--transition-timing);
}

.client-btn:hover {
  transform: translateY(-5px) scale(1.02);
}

.client-btn:active {
  transform: translateY(-2px) scale(0.99);
}

.client-btn span {
  font-size: 12px;
  color: var(--text-muted);
}

.large {
  min-height: 160px;
}

/* 页脚 */
.footer {
  text-align: center;
  margin-top: 40px;
  color: var(--text-muted);
}

/* 响应式 */
@media (max-width: 768px) {
  .app {
    padding: 16px;
  }
  .nav {
    flex-direction: column;
    gap: 16px;
    padding: 16px;
  }
  .menu {
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px 0;
  }
  .client-list {
    flex-direction: column;
  }
}

/* Modal Styles */
.modal-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-duration) ease-out;
}

.modal-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

.modal-content {
  background: var(--bg-card);
  border-radius: 22px;
  padding: 30px;
  width: 90%;
  max-width: 600px;
  position: relative;
  transform: scale(0.95);
  transition: transform var(--transition-duration) ease-out;
}

.modal-overlay.visible .modal-content {
  transform: scale(1);
}

.modal-close-btn {
  position: absolute;
  top: 15px;
  right: 20px;
  font-size: 28px;
  font-weight: bold;
  color: var(--text-muted);
  cursor: pointer;
  transition: color var(--transition-duration) ease-out;
}

.modal-close-btn:hover {
  color: var(--text-primary);
}