/* ============================================================
   BUTTON COMPONENT — Share Market Pro
   ============================================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.5625rem 1.25rem;
    font-size: 0.875rem;
    font-weight: 600;
    line-height: 1.5;
    border-radius: var(--radius-md);
    border: 1.5px solid transparent;
    transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast), transform 0.1s;
    cursor: pointer;
    white-space: nowrap;
    text-decoration: none;
    font-family: var(--font-sans);
    -webkit-user-select: none;
    user-select: none;
    letter-spacing: 0.01em;
}

.btn:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.btn:disabled,
.btn[aria-disabled="true"] {
    opacity: 0.4;
    cursor: not-allowed;
    pointer-events: none;
}

/* Sizes */
.btn--sm   { padding: 0.375rem 0.875rem; font-size: 0.8125rem; }
.btn--lg   { padding: 0.75rem 2rem; font-size: 1rem; }
.btn--full { width: 100%; }
.btn--icon { padding: 0.5rem; }

/* Variants */
.btn--primary {
    background: var(--color-accent);
    color: #000;
    border-color: var(--color-accent);
    font-weight: 700;
}
.btn--primary:hover {
    background: var(--color-accent-light);
    border-color: var(--color-accent-light);
    transform: translateY(-1px);
    box-shadow: 0 4px 20px rgba(0, 200, 83, 0.35);
}

.btn--secondary {
    background: var(--color-surface-elevated);
    color: var(--color-text-primary);
    border-color: var(--color-border-dark);
}
.btn--secondary:hover {
    background: var(--color-surface-hover);
    border-color: var(--color-border-dark);
}

.btn--ghost {
    background: transparent;
    color: var(--color-text-secondary);
    border-color: var(--color-border);
}
.btn--ghost:hover {
    background: var(--color-surface-elevated);
    color: var(--color-text-primary);
    border-color: var(--color-border-dark);
}

.btn--outline {
    background: transparent;
    color: var(--color-accent);
    border-color: var(--color-accent);
}
.btn--outline:hover {
    background: var(--color-accent-glow);
}

.btn--danger {
    background: var(--color-danger);
    color: #fff;
    border-color: var(--color-danger);
    font-weight: 700;
}
.btn--danger:hover {
    background: #e53935;
    border-color: #e53935;
    transform: translateY(-1px);
    box-shadow: 0 4px 16px rgba(244, 67, 54, 0.3);
}

.btn--outline-danger {
    background: transparent;
    color: var(--color-danger);
    border-color: var(--color-danger);
}
.btn--outline-danger:hover {
    background: rgba(244, 67, 54, 0.08);
}

/* Loading state */
.btn--loading {
    position: relative;
    color: transparent;
    pointer-events: none;
}
.btn--loading::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    border: 2px solid currentColor;
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    color: #000;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── Light Theme — Button overrides ────────────────────── */
[data-theme="light"] .btn--primary {
    color: #fff;
}
[data-theme="light"] .btn--primary:hover {
    box-shadow: 0 4px 20px rgba(0, 168, 68, 0.28);
}
[data-theme="light"] .btn--secondary:hover {
    border-color: rgba(0,0,0,0.15);
}
[data-theme="light"] .btn--ghost:hover {
    background: var(--color-surface-elevated);
    color: var(--color-text-primary);
}