.top-nav {
    position: sticky;
    top: 0;
    z-index: 1003;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    animation: slideInDown 0.6s ease;
}

[data-theme="dark"] .top-nav {
    background: rgba(26, 26, 46, 0.9);
    border-bottom-color: var(--dark-border);
    backdrop-filter: blur(10px);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.nav-icon-buttons {
    gap: 1rem;
    display: flex;
    justify-content: space-between;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo-icon {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: pulse 2s infinite;
}

.logo-icon img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
}

.logo-text .main-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    display: block;
}

.logo-text .sub-title {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 400;
}

.nav-actions-container {
    position: relative;
    display: flex;
    align-items: center;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

#mobile-menu-toggle {
    display: none;
}

.main-content {
    padding: 2rem 0;
    min-height: 60vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.explorer-container {
    display: flex;
    gap: 2rem;
}

.folder-tree-container {
    flex-shrink: 0;
    background: var(--background-secondary);
    padding: 1.5rem;
    border-radius: var(--border-radius-large);
    max-height: 800px;
    overflow-y: auto;
    position: sticky;
    top: 90px;
    width: 280px;
}

.folder-tree-container .section-title {
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

#file-explorer {
    flex-grow: 1;
}

.footer {
    margin-top: 4rem;
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: var(--primary-light);
}

.footer-section p {
    color: #BDC3C7;
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
    padding: 0;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: #BDC3C7;
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-section ul li a:hover {
    color: var(--primary-light);
}

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.social-link {
    width: 40px;
    height: 40px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
}

.footer-bottom {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid #34495E;
    text-align: center;
    color: #BDC3C7;
}

[data-theme="dark"] .footer {
    background: var(--dark-bg);
    color: var(--dark-text);
}

[data-theme="dark"] .footer-section p,
[data-theme="dark"] .footer-section ul li a {
    color: var(--dark-text-secondary);
}

[data-theme="dark"] .footer-section ul li a:hover {
    color: var(--primary-light);
}

[data-theme="dark"] .footer-bottom {
    border-top-color: var(--dark-border);
    color: var(--dark-text-secondary);
}

@media (max-width: 1200px) {
    .nav-container {
        padding: 0 1rem;
        height: 60px;
    }

    .logo-text .main-title {
        font-size: 1.2rem;
    }

    .container {
        padding: 0 1rem;
    }
}

@media (max-width: 1200px) {
    .nav-actions {
        display: none;
        position: absolute;
        top: 100%;
        right: 0;
        background: var(--background);
        border-radius: var(--border-radius-large);
        box-shadow: var(--shadow-large);
        border: 1px solid var(--border-color);
        flex-direction: column;
        align-items: stretch;
        width: 280px;
        padding: 1rem;
        z-index: 100;
        gap: 0.5rem;
    }

    .nav-actions.active {
        display: flex;
    }

    .nav-actions:not(:has(#auth-section)).active {
        display: flex;
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }

    .nav-actions #auth-section {
        display: flex;
        flex-direction: column;
        gap: 0.75rem;
        width: 100%;
    }

    .nav-actions #auth-section .user-info {
        display: flex;
        align-items: center;
        gap: 0.5rem;
        padding: 0.75rem;
        background: var(--background-alt);
        border-radius: var(--border-radius-medium);
        font-size: 0.95rem;
        width: 100%;
        box-sizing: border-box;
    }

    .nav-actions #auth-section .user-info .quota {
        margin-left: auto;
        font-size: 0.85rem;
        color: var(--text-secondary);
    }

    .nav-actions #auth-section .secondary-btn {
        flex: 1 1 calc(33.33% - 0.5rem);
        min-width: 0;
        justify-content: center;
        padding: 0.6rem 0.4rem;
        font-size: 0.85rem;
    }

    .nav-actions #auth-section {
        flex-wrap: wrap;
    }

    .nav-actions #auth-section .primary-btn {
        width: 100%;
        justify-content: center;
    }

    .nav-actions #auth-section #logout-btn {
        flex-basis: 100%;
        margin-top: 0.25rem;
        border-top: 1px solid var(--border-color);
        padding-top: 0.75rem;
        border-radius: 0 0 var(--border-radius-medium) var(--border-radius-medium);
    }

    #mobile-menu-toggle {
        display: inline-flex;
    }
}

.file-list-container.grid-view .file-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 1.5rem;
}

.file-list-container.grid-view .file-list-item {
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 1.5rem;
    background: var(--background-secondary);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow-soft);
    transition: all var(--transition-normal);
    position: relative;
}

.file-list-container.grid-view .file-list-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

.file-list-container.grid-view .file-item {
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    width: 100%;
}

.file-list-container.grid-view .file-icon {
    width: 80px;
    height: 80px;
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.file-list-container.grid-view .file-info {
    align-items: center;
    text-align: center;
}

.file-list-container.grid-view .file-name {
    font-size: 1rem;
    font-weight: 600;
    word-break: break-all;
}

.file-list-container.grid-view .file-meta {
    font-size: 0.8rem;
}

.file-list-container.grid-view .file-actions {
    margin-top: 1rem;
    justify-content: center;
    width: 100%;
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.file-list-container.grid-view .back-item .file-item {
    flex-direction: column;
}

.folder-tree-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.folder-tree-list .folder-tree-list {
    padding-left: 20px;
}

.folder-tree-node {
    margin-bottom: 4px;
}

.folder-tree-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 8px 12px;
    border-radius: var(--border-radius-medium);
    cursor: pointer;
    transition: background-color var(--transition-fast);
    user-select: none;
}

.folder-tree-item:hover {
    background-color: var(--background-hover);
}

.folder-tree-item.active {
    background-color: var(--background-alt);
}

.folder-tree-item.active .folder-item-main .folder-name {
    color: var(--primary-color);
    font-weight: 600;
}

.folder-tree-item.active .folder-item-main .folder-icon {
    color: var(--primary-color);
}

.folder-toggle-icon {
    width: 16px;
    text-align: center;
    margin-right: 8px;
    color: var(--text-secondary);
    transition: transform var(--transition-fast);
}

.folder-toggle-icon.hidden {
    visibility: hidden;
}

.folder-toggle-icon.expanded {
    transform: rotate(90deg);
}

.folder-icon {
    margin-right: 8px;
    color: var(--primary-color);
}

.folder-name {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 0.95rem;
}

.folder-item-main {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-grow: 1;
    overflow: hidden;
}

.go-to-folder-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 4px;
    border-radius: 50%;
    transition: background-color 0.2s, color 0.2s;
    flex-shrink: 0;
    margin-left: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
}

.go-to-folder-btn:hover {
    background-color: var(--background-hover);
    color: var(--primary-color);
}

.folder-tree-item.active .go-to-folder-btn {
    color: var(--primary-color);
}

.sidebar-divider {
    height: 1px;
    background-color: var(--border-color);
    margin: 1.5rem 0;
}

#hot-folders-list {
    margin-top: 1rem;
}

.hot-folders-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.hot-folder-item {
    display: flex;
    gap: 12px;
    justify-content: space-between;
    align-items: center;
    padding: 10px 12px;
    border-radius: var(--border-radius-medium);
    cursor: pointer;
    transition: background-color var(--transition-fast);
}

.hot-folder-item:hover {
    background-color: var(--background-hover);
}

.hot-folder-name {
    font-size: 0.95rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 8px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.hot-folder-name .fa-folder {
    color: var(--primary-color);
}

.hot-folder-downloads {
    font-size: 0.9rem;
    color: var(--accent-color);
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 6px;
    flex-shrink: 0;
}

.empty-state-small {
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-align: center;
    padding: 1rem 0;
}

.sidebar-cache-notice {
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-align: center;
    opacity: 0.7;
}

.sidebar-cache-notice i {
    margin-right: 0.3rem;
}

.logo-section .mobile-only-btn {
    display: none;
}

.mobile-sidebar-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1001;
    transition: opacity 0.3s ease;
}

@media (max-width: 1200px) {
    .logo-section .mobile-only-btn {
        display: inline-flex;
    }

    .explorer-container {
        flex-direction: column;
    }

    .folder-tree-container {
        position: fixed;
        top: 0;
        left: 0;
        max-height: none;
        height: 100%;
        max-width: 90%;
        z-index: 1002;
        transform: translateX(-100%);
        transition: transform 0.3s ease-in-out;
        background: var(--background);
        border-radius: 0;
        box-shadow: 0 0 20px rgba(0, 0, 0, 0.2);
        overflow-y: auto;
        padding-top: 6rem;
    }

    body.mobile-sidebar-visible .folder-tree-container {
        transform: translateX(0);
    }

    body.mobile-sidebar-visible .mobile-sidebar-overlay {
        display: block;
        opacity: 1;
    }
}