/* ============================================
   Sidebar Navigation
   ============================================ */

/* Sidebar container */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 320px;
    height: 100vh;
    background: var(--colour-background);
    border-right: 1px solid var(--colour-border);
    z-index: 90; /* Below header (which is z-index: 100) */
    overflow-y: auto;
    overflow-x: hidden;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Auto-hide sidebar on scroll down (desktop only) */
.sidebar.sidebar-hidden {
    transform: translateX(-100%); /* Fully hide sidebar */
}

/* Sidebar header (Home link) */
.sidebar-header {
    display: flex;
    justify-content: flex-start;
    align-items: center;
    padding: 1rem 1rem 1rem;
    border-bottom: 1px solid var(--colour-border);
    margin-bottom: 1rem;
    padding-bottom: 14px;
}

/* Scrollbar styling */
.sidebar::-webkit-scrollbar {
    width: 8px;
}

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

.sidebar::-webkit-scrollbar-thumb {
    background: var(--colour-border);
    border-radius: 4px;
}

.sidebar::-webkit-scrollbar-thumb:hover {
    background: var(--colour-text-muted);
}

/* Sidebar inner container */
.sidebar-content {
    padding: 1.5rem;
    padding-top: 0;
}

/* Sidebar header (Home link) - already defined above with collapse button */

.sidebar-home-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    text-decoration: none;
    color: var(--colour-text);
    font-weight: 600;
    border-radius: 8px;
    transition: all 0.2s ease;
}

.sidebar-home-link:hover {
    background: var(--colour-surface);
    transform: translateX(2px);
}

.sidebar-home-link .icon {
    font-size: 1.25rem;
}

/* Navigation sections */
.sidebar-section {
    margin-bottom: 1.5rem;
}

.sidebar-section-title {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1rem;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--colour-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    cursor: pointer;
    user-select: none;
    border-radius: 6px;
    transition: all 0.2s ease;
}

.sidebar-section-title:hover {
    background: var(--colour-surface);
    color: var(--colour-text);
}

.sidebar-section-icon {
    margin-right: 0.5rem;
}

.sidebar-section-toggle {
    font-size: 0.75rem;
    transition: transform 0.2s ease;
}

.sidebar-section.collapsed .sidebar-section-toggle {
    transform: rotate(-90deg);
}

/* Navigation links */
.sidebar-nav {
    list-style: none;
    padding: 0;
    margin: 0.5rem 0 0 0;
}

.sidebar-nav-item {
    margin-bottom: 0.25rem;
}

.sidebar-nav-link {
    display: block;
    padding: 0.625rem 1rem 0.625rem 2.5rem;
    color: var(--colour-text);
    text-decoration: none;
    font-size: 0.9375rem;
    border-radius: 6px;
    transition: all 0.2s ease;
    position: relative;
}

.sidebar-nav-link::before {
    content: '';
    position: absolute;
    left: 1.25rem;
    top: 50%;
    transform: translateY(-50%);
    width: 4px;
    height: 4px;
    background: var(--colour-text-muted);
    border-radius: 50%;
    opacity: 0.5;
    transition: all 0.2s ease;
}

.sidebar-nav-link:hover {
    background: var(--colour-surface);
    transform: translateX(2px);
    color: var(--colour-primary);
}

.sidebar-nav-link:hover::before {
    opacity: 1;
    background: var(--colour-primary);
    transform: translateY(-50%) scale(1.3);
}

/* Active/current page */
.sidebar-nav-link.active {
    background: var(--colour-primary);
    color: white;
    font-weight: 600;
}

.sidebar-nav-link.active::before {
    background: white;
    opacity: 1;
}

/* Collapsed section */
.sidebar-section.collapsed .sidebar-nav {
    display: none;
}

/* Back to top button */
.sidebar-footer {
    padding: 1rem;
    border-top: 1px solid var(--colour-border);
    margin-top: 2rem;
}

/* Hide the back-to-top button in sidebar (floating one is used instead) */
.sidebar-footer .back-to-top {
    display: none;
}

.back-to-top {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    width: 100%;
    padding: 0.75rem;
    background: var(--colour-surface);
    border: 1px solid var(--colour-border);
    border-radius: 8px;
    color: var(--colour-text);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.back-to-top:hover {
    background: var(--colour-primary);
    color: white;
    border-color: var(--colour-primary);
    transform: translateY(-2px);
}

/* Sidebar toggle button (mobile hamburger) */
.sidebar-toggle {
    position: fixed;
    top: var(--space-6); /* Aligned with theme toggle */
    left: 1rem; /* Position on left side */
    width: 48px; /* Match theme toggle size */
    height: 48px; /* Match theme toggle size */
    background: var(--colour-background);
    border: 1px solid var(--colour-border);
    border-radius: 8px;
    display: none; /* Hidden on desktop */
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 110;
    transition: all 0.2s ease;
}

.sidebar-toggle:hover {
    background: var(--colour-surface);
    border-color: var(--colour-primary);
}

.sidebar-toggle-icon {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.sidebar-toggle-icon span {
    width: 20px;
    height: 2px;
    background: var(--colour-text);
    border-radius: 2px;
    transition: all 0.3s ease;
}

/* Hamburger animation when open */
.sidebar-toggle.active .sidebar-toggle-icon span:nth-child(1) {
    transform: rotate(45deg) translateY(6px);
}

.sidebar-toggle.active .sidebar-toggle-icon span:nth-child(2) {
    opacity: 0;
}

.sidebar-toggle.active .sidebar-toggle-icon span:nth-child(3) {
    transform: rotate(-45deg) translateY(-6px);
}

/* Mobile backdrop */
.sidebar-backdrop {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 1;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.sidebar-backdrop.active {
    display: block;
    opacity: 1;
}

/* ============================================
   Desktop Layout (>= 1024px)
   ============================================ */

@media (min-width: 1024px) {
    /* Adjust main content and header for sidebar */
    body {
        padding-left: 320px;
        transition: padding-left 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

    /* When sidebar is auto-hidden on scroll */
    body.sidebar-hidden {
        padding-left: 0;
    }

    .site-header {
        left: 320px;
        width: calc(100% - 320px);
        transition: left 0.3s cubic-bezier(0.4, 0, 0.2, 1), width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

    /* When sidebar is auto-hidden on scroll */
    body.sidebar-hidden .site-header {
        left: 0;
        width: 100%;
    }

    /* Theme toggle stays on the right side of header - no left positioning needed */

    /* Hide extra nav items when sidebar is open (show only first 4) */
    body:not(.sidebar-hidden) .nav-list .nav-item:nth-child(n+5) {
        display: none;
    }

    .sidebar {
        transform: translateX(0);
    }
}

/* ============================================
   Tablet Layout (768px - 1023px)
   ============================================ */

@media (max-width: 1023px) {
    .sidebar {
        transform: translateX(-100%);
        box-shadow: 4px 0 20px rgba(0, 0, 0, 0.1);
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .sidebar-toggle {
        display: flex;
        left: 1rem; /* Position on left side */
        right: auto; /* Override default right positioning */
    }

    /* Hide old header nav toggle - we use sidebar toggle now */
    .nav-toggle {
        display: none !important;
    }

    /* Hide header nav items on mobile - sidebar has all navigation */
    .nav-list {
        display: none !important;
    }

    /* Add padding above Home to make space for toggle buttons */
    .sidebar-content {
        padding-top: 5rem; /* Space for toggle buttons */
    }

    /* Theme toggle positioning adjusted - both toggles now on left */
    .theme-toggle {
        top: var(--space-6) !important; /* Align with sidebar toggle */
        left: 4.5rem !important; /* Position to right of sidebar toggle */
    }

    /* Hide logo when sidebar is active to prevent overlap */
    .sidebar.active ~ header .logo {
        opacity: 0 !important;
        pointer-events: none;
        transition: opacity 0.3s ease;
    }
}

/* ============================================
   Mobile Layout (< 768px)
   ============================================ */

@media (max-width: 767px) {
    .sidebar {
        width: 85%;
        max-width: 320px;
    }

    .sidebar-nav-link {
        font-size: 1rem;
        padding: 0.875rem 1rem 0.875rem 2.5rem; /* 14px top/bottom = 28px + 16px font ≈ 44px touch target */
        min-height: 44px; /* Ensure minimum touch target */
    }

    .sidebar-section-title {
        font-size: 0.8125rem;
        padding: 0.875rem 1rem; /* Increase touch target */
        min-height: 44px;
    }

    .sidebar-home-link {
        padding: 0.875rem 1rem;
        min-height: 44px;
    }
}

/* ============================================
   Dark Mode Adjustments
   ============================================ */

.dark .sidebar {
    box-shadow: 0 0 40px rgba(0, 0, 0, 0.3);
}

.dark .sidebar-backdrop {
    background: rgba(0, 0, 0, 0.7);
}

/* ============================================
   Accessibility
   ============================================ */

.sidebar-nav-link:focus {
    outline: 2px solid var(--colour-primary);
    outline-offset: 2px;
}

.sidebar-section-title:focus {
    outline: 2px solid var(--colour-primary);
    outline-offset: 2px;
}

/* Reduce motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
    .sidebar,
    .sidebar-nav-link,
    .sidebar-section-toggle,
    .sidebar-toggle-icon span {
        transition: none;
    }
}

/* ============================================
   Print Styles
   ============================================ */

@media print {
    .sidebar,
    .sidebar-toggle,
    .sidebar-backdrop {
        display: none;
    }

    body {
        padding-left: 0;
    }
}

/* ============================================
   Floating Back to Top Button (Main Content)
   ============================================ */

.floating-back-to-top {
    position: fixed;
    bottom: 2rem;
    width: 56px;
    height: 56px;
    background: var(--colour-primary);
    color: white;
    border: none;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 4px 20px rgba(37, 99, 235, 0.4);
    z-index: 80;
    opacity: 0;
    visibility: hidden;
    transform: translateY(100px) scale(0.8);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    font-size: 1.5rem;
}

.floating-back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
}

.floating-back-to-top:hover {
    background: var(--colour-primary-dark);
    box-shadow: 0 6px 30px rgba(37, 99, 235, 0.6);
    transform: translateY(-4px) scale(1.05);
}

.floating-back-to-top:active {
    transform: translateY(-2px) scale(0.95);
}

/* Progress ring around button */
.floating-back-to-top::before {
    content: '';
    position: absolute;
    top: -4px;
    left: -4px;
    right: -4px;
    bottom: -4px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: var(--colour-accent);
    transition: transform 0.3s ease;
    transform: rotate(calc(var(--scroll-progress, 0) * 360deg));
}

/* Mobile adjustments */
@media (max-width: 767px) {
    .floating-back-to-top {
        width: 48px;
        height: 48px;
        bottom: 1.5rem;
        font-size: 1.25rem;
    }
}

/* Dark mode */
.dark .floating-back-to-top {
    box-shadow: 0 4px 20px rgba(96, 165, 250, 0.4);
}

.dark .floating-back-to-top:hover {
    box-shadow: 0 6px 30px rgba(96, 165, 250, 0.6);
}