:root {
    --bg: #f4f7f6;
    --sidebar: #1e293b;
    --card: #ffffff;
    --primary: #3b82f6;
    --text: #334155;
}

body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background: var(--bg); color: var(--text); margin: 0; }
.app-container { display: flex; min-height: 100vh; }
.sidebar { width: 250px; background: var(--sidebar); color: white; padding: 20px; }
.content { flex: 1; padding: 30px; }
.metrics-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 20px; }
.card { background: var(--card); padding: 20px; border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.1); }
.value { font-size: 1.5rem; font-weight: bold; color: var(--primary); }
.btn-primary { background: var(--primary); color: white; border: none; padding: 10px 20px; border-radius: 5px; cursor: pointer; }