:root {
    --bg: #f3f4f6;
    --card: #ffffff;
    --text: #1f2937;
    --primary: #3b82f6;
    --success: #10b981;
    --danger: #ef4444;
    --border: #e5e7eb;
}
[data-theme="dark"] {
    --bg: #111827;
    --card: #1f2937;
    --text: #f9fafb;
    --primary: #60a5fa;
    --border: #374151;
}
body { font-family: -apple-system, sans-serif; background: var(--bg); color: var(--text); padding: 20px; margin: 0; transition: background 0.3s; }
.container { max-width: 900px; margin: auto; }
.card { background: var(--card); padding: 20px; border-radius: 12px; margin-bottom: 20px; box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1); border: 1px solid var(--border); }
.header-flex { display: flex; justify-content: space-between; align-items: center; }

/* Typography & Layout */
h1, h2, h3 { margin-top: 0; }
.amount-big { font-size: 2.5rem; font-weight: bold; color: var(--success); }
.amount-big.negative { color: var(--danger); }
.btn { padding: 10px 15px; background: var(--primary); color: white; border: none; border-radius: 6px; cursor: pointer; font-weight: 600; }
.btn-danger { background: var(--danger); }
input, select { padding: 8px; border: 1px solid var(--border); border-radius: 6px; background: var(--bg); color: var(--text); }

/* CRUD Table */
table { width: 100%; border-collapse: collapse; margin-top: 10px; }
th, td { text-align: left; padding: 12px; border-bottom: 1px solid var(--border); }

/* Modals */
.modal { display: none; position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.5); align-items: center; justify-content: center; }
.modal-content { background: var(--card); padding: 20px; border-radius: 12px; width: 90%; max-width: 500px; }
.cat-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin: 15px 0; }
.cat-btn { padding: 15px; background: var(--bg); color: var(--text); border: 1px solid var(--border); border-radius: 8px; cursor: pointer; }
.cat-btn.selected { background: var(--primary); color: white; border-color: var(--primary); }