body {
    background-color: #f5f6fa;
    font-family: 'Segoe UI', sans-serif;
}

.sidebar {
    width: 220px;
    min-height: 100vh;
    background-color: #1a1f36;
    flex-shrink: 0;
}

.sidebar .brand {
    color: #fff;
    font-weight: 700;
    font-size: 1.1rem;
    padding: 1.5rem 1.25rem 1rem;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.sidebar .nav-link {
    color: rgba(255,255,255,0.65);
    padding: 0.6rem 1.25rem;
    border-radius: 6px;
    margin: 2px 8px;
    font-size: 0.9rem;
    transition: all 0.15s;
}

.sidebar .nav-link:hover,
.sidebar .nav-link.active {
    color: #fff;
    background-color: rgba(255,255,255,0.1);
}

.sidebar .nav-link i {
    width: 20px;
    margin-right: 8px;
    opacity: 0.7;
}

.main-content {
    flex-grow: 1;
    padding: 2rem;
    min-width: 0;
}

.stat-card {
    background: #fff;
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
    box-shadow: 0 1px 4px rgba(0,0,0,0.07);
    border-left: 4px solid;
}

.stat-card.blue  { border-color: #3b82f6; }
.stat-card.green { border-color: #22c55e; }
.stat-card.amber { border-color: #f59e0b; }
.stat-card.red   { border-color: #ef4444; }

.stat-card .label {
    font-size: 0.78rem;
    color: #6b7280;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-card .value {
    font-size: 1.8rem;
    font-weight: 700;
    color: #111827;
    line-height: 1.2;
}

.card {
    border: none;
    border-radius: 12px;
    box-shadow: 0 1px 4px rgba(0,0,0,0.07);
}

.card-header {
    background: #fff;
    border-bottom: 1px solid #f0f0f0;
    font-weight: 600;
    border-radius: 12px 12px 0 0 !important;
}

.table th {
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: #6b7280;
    font-weight: 600;
    border-bottom: 1px solid #e5e7eb;
}

.badge-overdue  { background-color: #fee2e2; color: #dc2626; }
.badge-due-soon { background-color: #fef3c7; color: #d97706; }
.badge-ok       { background-color: #dcfce7; color: #16a34a; }

.badge-payment { background-color: #dcfce7; color: #16a34a; }
.badge-charge  { background-color: #fee2e2; color: #dc2626; }

.btn-primary {
    background-color: #3b82f6;
    border-color: #3b82f6;
}

.login-card {
    max-width: 400px;
    margin: 8rem auto;
}