:root {
    --bg: #f8f9fa;
    --card-bg: #ffffff;
    --text: #212529;
    --primary: #4f46e5;
    --secondary: #6b7280;
    --border: #e5e7eb;
}

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

body {
    font-family: system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
}

.container { max-width: 800px; margin: 0 auto; padding: 2rem 1rem; }

header h1 { font-size: 1.8rem; margin-bottom: 2rem; }

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.btn-primary, .btn-secondary {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: opacity 0.2s;
}

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

.btn-primary:hover { opacity: 0.9; }

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 1rem;
}

.group-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
    text-align: center;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

.group-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.expense-item {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1rem;
    margin-bottom: 0.75rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.expense-info h4 { font-size: 1rem; }
.expense-info p { font-size: 0.85rem; color: var(--secondary); }
.expense-amount { font-weight: 600; color: var(--primary); }

.modal {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(0,0,0,0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
}

.modal-content {
    background: white;
    padding: 2rem;
    border-radius: 16px;
    width: 90%;
    max-width: 400px;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.modal-content input, .modal-content textarea {
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-family: inherit;
}

.hidden { display: none; }

/* Estados vacíos */
.empty-state {
    color: var(--secondary);
    text-align: center;
    padding: 2rem 0;
    grid-column: 1 / -1;
}

/* Modal: etiquetas y acciones */
.modal-content label {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--secondary);
    margin-bottom: -0.5rem;
}

.modal-actions {
    display: flex;
    justify-content: flex-end;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

/* Toast de notificación */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    background: #212529;
    color: #fff;
    padding: 0.75rem 1.25rem;
    border-radius: 999px;
    font-size: 0.9rem;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    z-index: 200;
    animation: fadeInUp 0.3s ease;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translate(-50%, 20px); }
    to   { opacity: 1; transform: translate(-50%, 0); }
}