/* ============================================================================
   SIDEBAR SUB-MENU STYLES
   Nested sub-menu items for existing sidebar navigation
   ============================================================================ */

/* ============================================
   SUB-MENU CONTAINER
   ============================================ */

.sidebar-submenu {
    overflow-y: auto;
    overflow-x: hidden;
    transition: max-height 0.3s ease, opacity 0.3s ease;
    opacity: 1;
    background: rgba(0, 0, 0, 0.05);
    border-left: 2px solid rgba(102, 126, 234, 0.3);
    margin-left: 0.75rem;
    margin-right: 0.5rem;
    border-radius: 0 0 8px 8px;
    max-height: 250px;
}

/* Scrollbar styling for sub-menu */
.sidebar-submenu::-webkit-scrollbar {
    width: 4px;
}

.sidebar-submenu::-webkit-scrollbar-track {
    background: transparent;
}

.sidebar-submenu::-webkit-scrollbar-thumb {
    background: rgba(102, 126, 234, 0.3);
    border-radius: 2px;
}

.sidebar-submenu::-webkit-scrollbar-thumb:hover {
    background: rgba(102, 126, 234, 0.5);
}

/* ============================================
   SUB-MENU ITEMS
   ============================================ */

.sidebar-submenu-item {
    display: flex !important;
    align-items: center;
    gap: 0.5rem;
    width: 100%;
    padding: 0.65rem 0.75rem 0.65rem 1.25rem;
    background: transparent;
    border: none;
    border-left: 3px solid transparent;
    color: var(--text-muted, #6C757D);
    cursor: pointer;
    font-family: 'Montserrat', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 0.75rem;
    font-weight: 500;
    text-align: left;
    transition: all 0.2s ease;
    position: relative;
    line-height: 1.3;
    white-space: normal;
    word-wrap: break-word;
}

.sidebar-submenu-item:hover {
    background: transparent;
    color: #667EEA;
    border-left-color: rgba(102, 126, 234, 0.5);
    padding-left: 1.35rem;
}

.sidebar-submenu-item.active {
    background: transparent;
    color: #667EEA;
    border-left-color: #667EEA;
    font-weight: 600;
    padding-left: 1.35rem;
}

/* ============================================
   SUB-MENU ITEM CONTENT
   ============================================ */

.submenu-icon {
    font-size: 0.95rem;
    line-height: 1;
    flex-shrink: 0;
    opacity: 0.8;
    min-width: 16px;
}

.sidebar-submenu-item.active .submenu-icon {
    opacity: 1;
}

.submenu-text {
    flex-grow: 1;
    line-height: 1.3;
    overflow-wrap: break-word;
    word-break: break-word;
    hyphens: auto;
}

/* ============================================
   PARENT NAV ITEM ENHANCEMENT
   ============================================ */

.nav-item.has-submenu {
    position: relative;
}

.nav-item.has-submenu::after {
    content: '▼';
    position: absolute;
    right: 1rem;
    font-size: 0.7rem;
    opacity: 0.5;
    transition: transform 0.3s ease;
}

.nav-item.has-submenu.expanded::after {
    transform: rotate(180deg);
}

/* ============================================
   SECTION ANIMATION
   ============================================ */

.overview-subsection {
    animation: fadeInSlideUp 0.4s ease;
}

@keyframes fadeInSlideUp {
    from {
        opacity: 0;
        transform: translateY(15px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================================
   RESPONSIVE - MOBILE
   ============================================ */

@media (max-width: 768px) {
    .sidebar-submenu-item {
        padding: 0.65rem 0.85rem 0.65rem 1.25rem;
        font-size: 0.8rem;
        gap: 0.5rem;
    }

    .sidebar-submenu-item:hover,
    .sidebar-submenu-item.active {
        padding-left: 1.5rem;
    }

    .submenu-icon {
        font-size: 1rem;
    }

    .submenu-text {
        font-size: 0.8rem;
    }
}

/* ============================================
   SIDEBAR COLLAPSED STATE
   ============================================ */

.modern-sidebar.collapsed .sidebar-submenu {
    display: none;
}

.modern-sidebar.collapsed .nav-item.has-submenu::after {
    display: none;
}

/* ============================================
   ACCESSIBILITY
   ============================================ */

.sidebar-submenu-item:focus {
    outline: none;
    background: transparent;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    .sidebar-submenu,
    .sidebar-submenu-item,
    .overview-subsection,
    .nav-item.has-submenu::after {
        transition: none;
        animation: none;
    }
}

/* High contrast mode */
@media (prefers-contrast: high) {
    .sidebar-submenu-item {
        border-width: 2px;
    }

    .sidebar-submenu-item.active {
        border-width: 4px;
    }
}

/* ============================================
   DARK THEME (OPTIONAL)
   ============================================ */

[data-theme="dark"] .sidebar-submenu {
    background: rgba(255, 255, 255, 0.05);
}

[data-theme="dark"] .sidebar-submenu-item {
    color: #ADB5BD;
}

[data-theme="dark"] .sidebar-submenu-item:hover {
    background: transparent;
    color: #7C8FEF;
}

[data-theme="dark"] .sidebar-submenu-item.active {
    background: transparent;
    color: #7C8FEF;
}