:root {
  --sidebar: #1e6cff;
  --sidebar-text: #ffffff;
  --sidebar-active: rgba(255, 255, 255, 0.18);
  --page: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --line: #eef2f7;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  height: 100%;
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--page);
}

.app {
  display: flex;
  min-height: 100vh;
  height: 100%;
}

.sidebar {
  width: 220px;
  flex: 0 0 220px;
  background: var(--sidebar);
  color: var(--sidebar-text);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.brand {
  height: 64px;
  display: flex;
  align-items: center;
  padding: 0 22px;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.04em;
  border-bottom: 1px solid rgba(255, 255, 255, 0.16);
}

.nav {
  display: flex;
  flex-direction: column;
  padding: 16px 12px;
  gap: 6px;
}

.nav-item {
  color: rgba(255, 255, 255, 0.92);
  text-decoration: none;
  padding: 12px 14px;
  border-radius: 10px;
  font-size: 15px;
}

.nav-item:hover,
.nav-item.is-active {
  background: var(--sidebar-active);
}

.main {
  flex: 1;
  min-width: 0;
  background: var(--page);
  display: flex;
  flex-direction: column;
}

.topbar {
  height: 64px;
  display: flex;
  align-items: center;
  padding: 0 28px;
  border-bottom: 1px solid var(--line);
}

.topbar h1 {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
}

.content {
  padding: 28px;
}

.content p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.7;
}

@media (max-width: 768px) {
  .sidebar {
    width: 72px;
    flex-basis: 72px;
  }

  .brand {
    justify-content: center;
    padding: 0;
    font-size: 14px;
  }

  .nav-item {
    text-align: center;
    padding: 12px 8px;
    font-size: 12px;
  }
}