.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 0.625rem 1.5rem;
    font-family: var(--font-body);
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-base);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    text-transform: uppercase;
    letter-spacing: var(--letter-spacing-wide);
    cursor: pointer;
    border: none;
    white-space: nowrap;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-brand);
}

.btn-primary:hover {
    background: var(--gradient-brand);
    box-shadow: var(--shadow-brand-lg);
    transform: translateY(-1px);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background: var(--color-bg-card-hover);
    border-color: var(--color-primary);
}

.btn-outline {
    background: transparent;
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

.btn-outline:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.btn-success {
    background: var(--color-success);
    color: white;
}

.btn-danger {
    background: var(--color-error);
    color: white;
}

.btn-whatsapp {
    background: var(--color-whatsapp);
    color: white;
}

.btn-messenger {
    background: var(--color-messenger);
    color: white;
}

.btn-lg {
    padding: 0.875rem 2rem;
    font-size: var(--font-size-lg);
}

.btn-sm {
    padding: 0.375rem 1rem;
    font-size: var(--font-size-sm);
}

.btn-block {
    width: 100%;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.btn .spinner {
    width: 16px;
    height: 16px;
    border: 2px solid transparent;
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

.btn-glow {
    animation: btnPulse 2s infinite;
}

@keyframes btnPulse {
    0%, 100% { box-shadow: 0 4px 15px rgba(108, 92, 231, 0.4); }
    50% { box-shadow: 0 4px 30px rgba(108, 92, 231, 0.7); }
}