:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #64748b;
    --success: #22c55e;
    --danger: #ef4444;
    --background: #f8fafc;
    --surface: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border: #e2e8f0;
    --radius: 8px;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Navigation */
header {
    background-color: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand a {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    align-items: center;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary);
}

.btn-logout {
    background-color: var(--danger);
    color: white !important;
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
}

/* Main content */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: calc(100vh - 180px);
}

/* Page header */
.page-header {
    margin-bottom: 2rem;
}

.page-header h1 {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.page-header p {
    color: var(--text-secondary);
}

/* Cards */
.card {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem;
    text-align: center;
}

.stat-value {
    font-size: 2rem;
    font-weight: 600;
    color: var(--primary);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Filters */
.filters {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    margin-bottom: 1.5rem;
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: flex-end;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.filter-group label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.filter-group input,
.filter-group select {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 0.875rem;
    min-width: 150px;
}

.filter-group input:focus,
.filter-group select:focus {
    outline: none;
    border-color: var(--primary);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border: none;
    border-radius: var(--radius);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
    text-decoration: none;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-dark);
}

.btn-secondary {
    background-color: var(--secondary);
    color: white;
}

.btn-success {
    background-color: var(--success);
    color: white;
}

.btn-sm {
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
}

/* Table */
.table-container {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

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

th, td {
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

th {
    background-color: var(--background);
    font-weight: 600;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

tr:hover {
    background-color: var(--background);
}

tr:last-child td {
    border-bottom: none;
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    margin-top: 1.5rem;
}

.pagination a,
.pagination span {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    text-decoration: none;
    color: var(--text-primary);
}

.pagination a:hover {
    background-color: var(--background);
}

.pagination .current {
    background-color: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* Detail page */
.detail-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.detail-item {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border);
}

.detail-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.detail-value {
    font-weight: 500;
}

/* Login page */
.login-container {
    max-width: 400px;
    margin: 4rem auto;
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.login-form input {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 1rem;
}

.login-form input:focus {
    outline: none;
    border-color: var(--primary);
}

.error-message {
    background-color: #fef2f2;
    border: 1px solid #fecaca;
    color: var(--danger);
    padding: 0.75rem 1rem;
    border-radius: var(--radius);
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--text-secondary);
}

/* Connected Devices */
.connected-devices {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    margin-bottom: 1.5rem;
}

.devices-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.devices-icon {
    font-size: 1.25rem;
}

.devices-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.device-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background-color: var(--background);
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius);
    font-size: 0.875rem;
}

.device-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: var(--success);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.device-name {
    font-weight: 500;
}

.device-initials {
    color: var(--text-secondary);
}

.device-time {
    color: var(--text-secondary);
    font-size: 0.75rem;
}

/* Footer */
footer {
    text-align: center;
    padding: 1.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    border-top: 1px solid var(--border);
}

/* Responsive */
@media (max-width: 768px) {
    .filters {
        flex-direction: column;
    }

    .filter-group input,
    .filter-group select {
        width: 100%;
    }

    .detail-grid {
        grid-template-columns: 1fr;
    }

    table {
        font-size: 0.875rem;
    }

    th, td {
        padding: 0.5rem;
    }
}