#nav-sidebar {
    position: fixed;
    left: 20px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 900;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 5px;
    background: rgba(26, 26, 26, 0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid rgba(58, 58, 58, 0.6);
    border-radius: 22px;
    padding: 14px 8px;
    max-height: min(85vh, 700px);
    width: 56px;
    box-shadow: 0 12px 48px rgba(0, 0, 0, 0.6);
    transition: width 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94),
                padding 0.4s ease,
                box-shadow 0.4s ease,
                opacity 0.3s ease,
                transform 0.3s ease;
    opacity: 0;
    transform: translateY(-50%) scale(0.95);
    pointer-events: none;
    overflow: hidden;
}

#nav-sidebar.visible {
    opacity: 1;
    transform: translateY(-50%) scale(1);
    pointer-events: auto;
}

#nav-sidebar.expanded,
#nav-sidebar.pinned {
    width: 480px;
    padding: 18px 16px;
    box-shadow: 0 16px 64px rgba(0, 0, 0, 0.8);
}

.nav-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    margin-bottom: 2px;
}

.reading-time {
    font-size: 13px;
    color: var(--text-secondary, #a0a0a0);
    white-space: nowrap;
    opacity: 0.8;
    padding-right: 4px;
    transition: opacity 0.2s ease;
}

#nav-sidebar.expanded .reading-time,
#nav-sidebar.pinned .reading-time {
    opacity: 1;
}

.nav-arrow {
    background: transparent;
    border: none;
    color: var(--text-secondary, #a0a0a0);
    cursor: pointer;
    padding: 5px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    flex-shrink: 0;
    margin-bottom: 0;
    outline: none;
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
    transition: color 0.2s ease,
                background 0.2s ease,
                box-shadow 0.1s ease;
}

.nav-arrow:hover {
    color: var(--accent, #4a9eff);
    background: rgba(74, 158, 255, 0.15);
}

.nav-arrow:active {
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.3);
    color: var(--accent, #4a9eff);
    background: rgba(74, 158, 255, 0.2);
}

.nav-arrow:focus-visible {
    outline: 2px solid var(--accent, #4a9eff);
    outline-offset: 2px;
}

.nav-arrow svg {
    display: block;
    width: 22px;
    height: 22px;
    stroke-width: 2.2;
    flex-shrink: 0;
    transition: none;
}

.nav-footer {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 2px;
    width: 100%;
    margin-top: 2px;
}

.pin-btn {
    transition: color 0.2s ease, background 0.2s ease, transform 0.15s ease;
}

.pin-btn.active {
    color: var(--accent, #4a9eff);
    background: rgba(74, 158, 255, 0.2);
}

.pin-btn.active:hover {
    background: rgba(74, 158, 255, 0.3);
}

#toc-wrapper {
    flex: 1;
    min-height: 0;
    width: 100%;
    overflow: hidden;
    position: relative;
    margin: 4px 0;
    transition: max-height 0.3s ease, margin 0.3s ease, padding 0.3s ease;
}

#toc-wrapper .ds-scroll-area {
    height: 100%;
    width: 100%;
    position: relative;
}

#toc-wrapper .ds-scroll-area__gutters {
    --dsl-scroll-area-gutters-disappear-delay: 0;
    --container-height: 120px;
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
    width: 100%;
    height: 0;
}

#toc-wrapper .ds-scroll-area__horizontal-gutter {
    left: 2px;
    right: 2px;
    display: block;
    top: calc(var(--container-height) - 8px);
    height: 6px;
}

#toc-wrapper .ds-scroll-area__horizontal-bar,
#toc-wrapper .ds-scroll-area__vertical-bar {
    display: none;
}

#toc-wrapper .ds-scroll-area__vertical-gutter {
    right: 2px;
    top: 8px;
    bottom: calc(0px - var(--container-height) + 8px);
    width: 6px;
}

#toc-wrapper .ds-virtual-list {
    --container-height: 120px;
    --dsl-virtual-list-width: 240px;
    max-height: 380px;
    overflow-y: auto;
    width: 100%;
    height: 100%;
    scrollbar-width: thin;
    scrollbar-color: var(--border-color, #3a3a3a) transparent;
    overscroll-behavior: contain;
}

#toc-wrapper .ds-virtual-list::-webkit-scrollbar {
    width: 5px;
}

#toc-wrapper .ds-virtual-list::-webkit-scrollbar-track {
    background: transparent;
}

#toc-wrapper .ds-virtual-list::-webkit-scrollbar-thumb {
    background: var(--border-color, #3a3a3a);
    border-radius: 6px;
}

#toc-wrapper .ds-virtual-list-items {
    box-sizing: content-box;
    padding: 15px 0 15px 24px;
    height: auto;
}

#toc-wrapper .ds-virtual-list-visible-items {
    position: relative;
    transform: translateY(0);
    display: flex;
    flex-direction: column;
    gap: 4px;
    width: 100%;
}

#toc-wrapper .ds-virtual-list-spacer {
    padding-bottom: 15px;
}

#toc-wrapper .ds-scroll-area__gutters,
#toc-wrapper .ds-scroll-area__horizontal-gutter,
#toc-wrapper .ds-scroll-area__vertical-gutter {
    display: none !important;
}

#toc-wrapper ._81e7b5e {
    display: flex;
    align-items: center;
    padding: 8px 14px;
    border-radius: 10px;
    font-size: 16px;
    line-height: 1.5;
    color: var(--text-secondary, #a0a0a0);
    text-decoration: none;
    cursor: pointer;
    transition: color 0.2s ease, background 0.2s ease, padding-left 0.15s ease;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-weight: 400;
    letter-spacing: 0.02em;
    border-left: 3px solid transparent;
    max-width: 100%;
    gap: 12px;
}

#toc-wrapper ._81e7b5e:hover {
    color: var(--text-primary, #e0e0e0);
    background: rgba(255, 255, 255, 0.07);
    border-left-color: var(--accent, #4a9eff);
}

#toc-wrapper ._81e7b5e._19d617c {
    color: var(--accent, #4a9eff);
    background: rgba(74, 158, 255, 0.1);
    border-left-color: var(--accent, #4a9eff);
    font-weight: 600;
}

#toc-wrapper ._72b6158 {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
}

#toc-wrapper .ef46fbc6 {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

#toc-wrapper .fae5876e {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--accent, #4a9eff);
    opacity: 0;
    transition: opacity 0.2s ease;
}

#toc-wrapper ._81e7b5e._19d617c .fae5876e {
    opacity: 1;
    animation: pulse-dot 1.5s ease-in-out infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.4); }
}

#toc-wrapper ._81e7b5e.level-1 {
    padding-left: 16px;
    font-weight: 600;
}

#toc-wrapper ._81e7b5e.level-2 {
    padding-left: 36px;
    font-size: 15px;
}

#toc-wrapper ._81e7b5e.level-3 {
    padding-left: 56px;
    font-size: 14px;
    opacity: 0.85;
}

#toc-wrapper ._81e7b5e.level-4 {
    padding-left: 76px;
    font-size: 13px;
    opacity: 0.7;
}

#toc-wrapper ._81e7b5e.level-5 {
    padding-left: 96px;
    font-size: 12px;
    opacity: 0.6;
}

#toc-wrapper ._81e7b5e.level-6 {
    padding-left: 116px;
    font-size: 11px;
    opacity: 0.5;
}

.reading-progress {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    padding: 2px 0;
    margin-top: 2px;
    transition: opacity 0.3s ease;
}

.progress-bar {
    flex: 1;
    height: 4px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    overflow: hidden;
    transition: height 0.2s ease;
}

#nav-sidebar.expanded .progress-bar,
#nav-sidebar.pinned .progress-bar {
    height: 6px;
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: var(--accent, #4a9eff);
    border-radius: 4px;
    transition: width 0.2s ease;
}

.progress-text {
    font-size: 12px;
    color: var(--text-secondary, #a0a0a0);
    min-width: 36px;
    text-align: right;
    opacity: 0.7;
    transition: opacity 0.2s ease;
}

#nav-sidebar.expanded .progress-text,
#nav-sidebar.pinned .progress-text {
    opacity: 1;
}

#nav-sidebar:not(.expanded):not(.pinned) .reading-time,
#nav-sidebar:not(.expanded):not(.pinned) #toc-wrapper,
#nav-sidebar:not(.expanded):not(.pinned) .reading-progress,
#nav-sidebar:not(.expanded):not(.pinned) .pin-btn {
    opacity: 0;
    pointer-events: none;
}

#nav-sidebar:not(.expanded):not(.pinned) #toc-wrapper {
    max-height: 0 !important;
    margin: 0;
    padding: 0;
}

@media (max-width: 1024px) {
    #nav-sidebar {
        left: 14px;
        padding: 12px 6px;
        width: 48px;
        border-radius: 18px;
        gap: 5px;
    }

    #nav-sidebar.expanded,
    #nav-sidebar.pinned {
        width: 380px;
        padding: 14px 12px;
    }

    .nav-arrow {
        width: 34px;
        height: 34px;
        padding: 4px;
    }

    .nav-arrow svg {
        width: 18px;
        height: 18px;
    }

    .reading-time {
        font-size: 11px;
    }

    #toc-wrapper .ds-virtual-list {
        max-height: 300px;
    }

    #toc-wrapper ._81e7b5e {
        font-size: 14px;
        padding: 8px 12px;
        border-left-width: 2px;
    }

    #toc-wrapper ._81e7b5e.level-1 { padding-left: 12px; }
    #toc-wrapper ._81e7b5e.level-2 { padding-left: 28px; font-size: 13px; }
    #toc-wrapper ._81e7b5e.level-3 { padding-left: 44px; font-size: 12px; }
    #toc-wrapper ._81e7b5e.level-4 { padding-left: 60px; font-size: 11px; }
    #toc-wrapper ._81e7b5e.level-5 { padding-left: 76px; font-size: 10px; }
    #toc-wrapper ._81e7b5e.level-6 { padding-left: 92px; font-size: 9px; }

    .progress-text {
        font-size: 10px;
        min-width: 30px;
    }
}

@media (max-width: 640px) {
    #nav-sidebar {
        display: none !important;
    }
}

#toc-wrapper .ds-virtual-list:empty {
    display: none;
}

@supports (padding: max(0px)) {
    #nav-sidebar {
        left: max(20px, env(safe-area-inset-left));
    }
}

#nav-sidebar.scrolled {
    opacity: 0.6;
}

#nav-sidebar.scrolled:hover {
    opacity: 1;
}

html {
    scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    #nav-sidebar * {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
}