/* ============================================
   УНИВЕРСАЛЬНЫЕ КНОПКИ
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: 0.8rem 2rem;
    border: none;
    border-radius: var(--radius-full);
    font-family: var(--font-family);
    font-size: var(--font-base);
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s ease;
}
 
.btn-sm { padding: 0.4rem 1.2rem; font-size: var(--font-sm); }
.btn-lg { padding: 1rem 2.5rem; font-size: var(--font-lg); }
.btn-block { width: 100%; justify-content: center; }

.btn-primary { background: var(--color-white); color: var(--color-primary); }
.btn-primary:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }

.btn-secondary { background: transparent; color: var(--color-white); border: 2px solid var(--color-white); }
.btn-secondary:hover { background: var(--color-white); color: var(--color-primary); transform: translateY(-3px); }

.btn-success { background: var(--color-success); color: var(--color-white); }
.btn-success:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }

.btn-outline { background: transparent; color: var(--color-primary); border: 2px solid var(--color-primary); }
.btn-outline:hover { background: var(--color-primary); color: var(--color-white); transform: translateY(-3px); }

.btn-dark { background: var(--color-gray-900); color: var(--color-white); }
.btn-dark:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }

.btn-stack { display: flex; gap: var(--space-md); flex-wrap: wrap; }

@media (max-width: 768px) {
    .btn-stack { flex-direction: column; align-items: stretch; }
    .btn { padding: 0.6rem 1.5rem; font-size: var(--font-sm); }
}