:root {
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --border: #e2e8f0;
  
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --offline: #94a3b8;

  --sidebar-w: 260px;
  --radius: 12px;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
      --bg-main: #0f172a;
      --bg-card: #1e293b;
      --text-main: #f8fafc;
      --text-muted: #94a3b8;
      --border: #334155;
  }
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* LOGIN SCREEN */
.screen { display: none; min-height: 100vh; }
.screen.active { display: flex; }

#login-screen {
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: 2rem;
}

.login-card {
  background: var(--bg-card);
  padding: 2.5rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  width: 100%;
  max-width: 400px;
  border: 1px solid var(--border);
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.form-input {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-main);
  color: var(--text-main);
  font-family: inherit;
  font-size: 1rem;
  transition: all 0.2s;
}

.form-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.btn-primary {
  width: 100%;
  padding: 0.75rem 1.5rem;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.btn-primary:hover { background: var(--primary-hover); }
.btn-primary:active { transform: scale(0.98); }

.btn-secondary {
  padding: 0.5rem 1rem;
  background: var(--bg-main);
  color: var(--text-main);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}
.btn-secondary:hover { background: var(--border); }

/* LAYOUT DASHBOARD */
.layout-wrapper {
  display: flex;
  width: 100%;
  height: 100vh;
  overflow: hidden;
}

.sidebar {
  width: var(--sidebar-w);
  background: var(--bg-card);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  transition: transform 0.3s ease;
}

.sidebar-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.sidebar-header h2 {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  color: var(--primary);
}

.sidebar-menu {
  list-style: none;
  padding: 1rem 0;
  flex: 1;
  overflow-y: auto;
}

.sidebar-menu li {
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  border-left: 3px solid transparent;
}

.sidebar-menu li:hover {
  background: var(--bg-main);
  color: var(--text-main);
}

.sidebar-menu li.active {
  background: rgba(59, 130, 246, 0.1);
  color: var(--primary);
  border-left-color: var(--primary);
}

.sidebar-footer {
  padding: 1.5rem;
  border-top: 1px solid var(--border);
}

.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.topbar {
  height: 64px;
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
}

.content-area {
  flex: 1;
  overflow-y: auto;
  padding: 2rem;
}

/* CARDS */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.stat-card {
  background: var(--bg-card);
  padding: 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.stat-title {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-main);
}

/* TABLES */
.table-container {
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.table-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th {
  text-align: center;
  padding: 1rem 1.5rem;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  font-weight: 600;
  background: rgba(0,0,0,0.02);
  border-bottom: 1px solid var(--border);
}

td {
  text-align: center;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.875rem;
}

tr:last-child td { border-bottom: none; }
tr:hover td { background: var(--bg-main); }

/* BADGES */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
}
.badge.online { background: rgba(16, 185, 129, 0.1); color: var(--success); }
.badge.offline { background: rgba(148, 163, 184, 0.1); color: var(--offline); }
.badge.syncing { background: rgba(245, 158, 11, 0.1); color: var(--warning); }

/* UTILITIES */
.view-section { display: none; }
.view-section.active { display: block; animation: fadeIn 0.3s ease; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(5px); }
  to { opacity: 1; transform: translateY(0); }
}

.flex-between { display: flex; justify-content: space-between; align-items: center; }
.gap-2 { display: flex; gap: 0.5rem; }
.gap-4 { display: flex; gap: 1rem; }

/* MOBILE */
.mobile-toggle { display: none; cursor: pointer; }
@media (max-width: 768px) {
  .sidebar {
      position: fixed;
      z-index: 50;
      height: 100%;
      transform: translateX(-100%);
  }
  .sidebar.show { transform: translateX(0); }
  .mobile-toggle { display: block; }
  .topbar { padding: 0 1rem; }
  .content-area { padding: 1rem; }
  
  /* Make tables responsive */
  table, thead, tbody, th, td, tr { display: block; }
  thead tr { position: absolute; top: -9999px; left: -9999px; }
  tr { border: 1px solid var(--border); margin-bottom: 1rem; border-radius: 8px; }
  td {
      border: none;
      border-bottom: 1px solid var(--border);
      position: relative;
      padding-left: 50%;
  }
  td:before {
      position: absolute;
      top: 1rem;
      left: 1rem;
      width: 45%;
      padding-right: 10px;
      white-space: nowrap;
      content: attr(data-label);
      font-weight: 600;
      color: var(--text-muted);
      font-size: 0.75rem;
  }
}

/* LOADER */
.loader {
  border: 3px solid var(--border);
  border-radius: 50%;
  border-top: 3px solid var(--primary);
  width: 20px;
  height: 20px;
  animation: spin 1s linear infinite;
}
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }

.empty-state {
  padding: 4rem 2rem;
  text-align: center;
  color: var(--text-muted);
}