/* NexusNote Web Editor (Client-Side) - v8.5 Responsive UI by Gemini */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR:wght@400;500;700&family=Noto+Sans:wght@400;500;700&family=Noto+Sans+Arabic:wght@400;500;700&family=Noto+Sans+Hebrew:wght@400;500;700&family=Noto+Sans+JP:wght@400;500;700&family=Noto+Sans+SC:wght@400;500;700&family=Noto+Sans+TC:wght@400;500;700&display=swap');

:root {
    --font-family: 'Noto Sans', 'Noto Sans KR', sans-serif;
    --header-height: 60px;
    --panel-header-height: 52px;
    --transition-speed-fast: 0.2s;
    --transition-speed-normal: 0.3s;
    --border-radius-small: 8px;
    --border-radius-medium: 12px;
    --border-radius-large: 16px;
}

body.theme-light {
    --primary-color: #4A5C9A;
    --primary-container: #DDE1FF;
    --on-primary: #FFFFFF;
    --on-primary-container: #00164D;
    --background-color: #F7F8FC;
    --surface-color: #FFFFFF;
    --surface-container: #F3F4F9;
    --surface-variant: #E1E2EC;
    --on-surface: #1A1B21;
    --on-surface-variant: #44474F;
    --outline-color: #757780;
    --danger-color: #BA1A1A;
    --on-danger: #FFFFFF;
    --danger-container: #FFDAD6;
    --on-danger-container: #410002;
    --scrim: rgba(0, 0, 0, 0.4);
    --tree-line-color: #DCDFE4;
}

body.theme-dark {
    --primary-color: #B7C4FF;
    --primary-container: #324481;
    --on-primary: #192D68;
    --on-primary-container: #DDE1FF;
    --background-color: #121318;
    --surface-color: #1A1B21;
    --surface-container: #23252B;
    --surface-variant: #44474F;
    --on-surface: #E3E2E9;
    --on-surface-variant: #C5C6D0;
    --outline-color: #8E9099;
    --danger-color: #FFB4AB;
    --on-danger: #690005;
    --danger-container: #93000A;
    --on-danger-container: #FFDAD6;
    --scrim: rgba(0, 0, 0, 0.6);
    --tree-line-color: #3A3D44;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
    overflow: hidden;
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--on-surface);
}

/* --- Landing Page --- */
#landing-page {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    text-align: center;
}
.landing-content {
    max-width: 500px;
    padding: 24px;
}
.landing-content h1 {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 12px;
    font-size: 32px;
    font-weight: 700;
    color: var(--on-surface);
    margin-bottom: 16px;
}
.landing-content h2 {
    font-size: 24px;
    font-weight: 500;
    margin-bottom: 8px;
}
.landing-content p {
    font-size: 16px;
    color: var(--on-surface-variant);
    margin-bottom: 32px;
}
.landing-actions {
    display: flex;
    flex-direction: column;
    gap: 16px;
}
.landing-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 14px 24px;
    font-size: 16px;
    font-weight: 500;
    border-radius: var(--border-radius-large);
    border: none;
    cursor: pointer;
    background-color: var(--primary-color);
    color: var(--on-primary);
    transition: opacity var(--transition-speed-fast);
}
.landing-button:hover {
    opacity: 0.9;
}
.landing-button.secondary {
    background-color: var(--surface-container);
    color: var(--on-surface);
    border: 1px solid var(--outline-color);
}
.landing-button.secondary:hover {
    background-color: var(--surface-variant);
}
.web-address {
    margin-top: 32px !important;
    font-size: 14px !important;
    color: var(--on-surface-variant) !important;
}

/* --- Main Layout --- */
#app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    position: relative;
    overflow: hidden;
}

header {
    height: var(--header-height);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 16px;
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--surface-variant);
    flex-shrink: 0;
    z-index: 10;
}

#main-content {
    display: flex;
    flex-grow: 1;
    overflow: hidden;
}

#left-panel {
    width: 320px;
    min-width: 280px;
    max-width: 500px;
    background-color: var(--surface-color);
    border-right: 1px solid var(--surface-variant);
    display: flex;
    flex-direction: column;
    resize: horizontal;
    overflow: auto;
    transition: transform var(--transition-speed-normal);
    z-index: 5;
}

#editor-container {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

/* --- Header --- */
.header-left, .header-right {
    display: flex;
    align-items: center;
    gap: 16px;
}
.header-left h1 {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 22px;
    font-weight: 500;
    color: var(--on-surface);
}
.header-icon {
    color: var(--primary-color);
}
.sync-status {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 14px;
    color: var(--on-surface-variant);
}
#sync-status-icon {
    font-size: 18px;
}
#sync-status-icon.syncing {
    animation: spin 1.5s linear infinite;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* --- Left Panel --- */
.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 16px;
    height: var(--panel-header-height);
    border-bottom: 1px solid var(--surface-variant);
    flex-shrink: 0;
}
.panel-header h2 {
    font-size: 16px;
    font-weight: 500;
}
#folder-list-container, #note-list-container {
    overflow-y: auto;
    flex-shrink: 1;
}
#folder-list-container {
    padding: 8px;
    min-height: 150px;
}
#note-list-container {
    border-top: 1px solid var(--surface-variant);
    flex-grow: 1;
}
#note-list {
    list-style-type: none;
}

/* --- New Folder Tree UI --- */
.folder-tree, .folder-tree ul {
    list-style-type: none;
    padding-left: 0;
    position: relative;
}
.folder-tree ul {
    padding-left: 22px;
}
.folder-item {
    position: relative;
}
.folder-item .folder-content {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 8px;
    border-radius: var(--border-radius-small);
    cursor: pointer;
    user-select: none;
    transition: background-color var(--transition-speed-fast);
}
.folder-item .folder-content:hover {
    background-color: var(--surface-container);
}
.folder-item.selected > .folder-content {
    background-color: var(--primary-container);
    color: var(--on-primary-container);
    font-weight: 500;
}
.folder-item.drag-over > .folder-content {
    background-color: var(--primary-container);
    outline: 2px solid var(--primary-color);
}
.folder-toggle {
    width: 20px;
    height: 20px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    visibility: hidden;
}
.folder-toggle.visible {
    visibility: visible;
}
.folder-toggle .material-symbols-outlined {
    font-size: 24px;
    transition: transform var(--transition-speed-fast);
}
.folder-item.collapsed .folder-toggle .material-symbols-outlined {
    transform: rotate(-90deg);
}
.folder-item > ul {
    display: block;
}
.folder-item.collapsed > ul {
    display: none;
}
.folder-icon {
    font-size: 20px;
}
.folder-tree ul::before {
    content: '';
    position: absolute;
    left: 10px;
    top: -8px;
    bottom: 8px;
    width: 1px;
    background-color: var(--tree-line-color);
}
.folder-item::before {
    content: '';
    position: absolute;
    left: -12px;
    top: 17px;
    width: 12px;
    height: 1px;
    background-color: var(--tree-line-color);
}
.folder-item:last-child::after {
    content: '';
    position: absolute;
    left: -22px;
    top: 18px;
    bottom: 0;
    width: 1px;
    background: var(--surface-color);
}


/* --- Note List --- */
.note-item {
    padding: 10px 16px;
    cursor: pointer;
    border-bottom: 1px solid var(--surface-variant);
    transition: background-color var(--transition-speed-fast);
}
.note-item:last-child {
    border-bottom: none;
}
.note-item:hover {
    background-color: var(--surface-container);
}
.note-item.selected {
    background-color: var(--primary-container);
}
.note-item.selected .note-item-title {
    color: var(--on-primary-container);
    font-weight: 700;
}
.note-item.selected .note-item-snippet {
    color: var(--on-primary-container);
}
.note-item-title {
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    margin-bottom: 4px;
}
.note-item-snippet {
    font-size: 14px;
    color: var(--on-surface-variant);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* --- Editor --- */
#editor-content {
    display: flex;
    flex-direction: column;
    height: 100%;
}
#editor-toolbar {
    display: flex;
    align-items: center;
    padding: 8px 16px;
    border-bottom: 1px solid var(--surface-variant);
    gap: 16px;
}
#note-title-input {
    flex-grow: 1;
    font-size: 20px;
    font-weight: 500;
    border: none;
    outline: none;
    background: transparent;
    color: var(--on-surface);
}
.toolbar-actions {
    display: flex;
    gap: 8px;
}
#note-content-textarea {
    flex-grow: 1;
    padding: 16px;
    border: none;
    outline: none;
    resize: none;
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    background: transparent;
    color: var(--on-surface);
}
#editor-empty-state {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 100%;
    color: var(--on-surface-variant);
    user-select: none;
}
#editor-empty-state .material-symbols-outlined {
    font-size: 64px;
}
#editor-empty-state p {
    margin-top: 16px;
    font-size: 18px;
    max-width: 300px;
    text-align: center;
    line-height: 1.5;
}

/* --- Buttons --- */
.icon-button {
    background: transparent;
    border: none;
    cursor: pointer;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: inline-flex;
    justify-content: center;
    align-items: center;
    color: var(--on-surface-variant);
    transition: background-color var(--transition-speed-fast);
    position: relative;
}
.icon-button:hover {
    background-color: var(--surface-container);
}
.icon-button.danger:hover {
    background-color: var(--danger-container);
    color: var(--on-danger-container);
}
.dialog-button {
    padding: 10px 20px;
    border: none;
    border-radius: var(--border-radius-large);
    cursor: pointer;
    font-weight: 500;
    transition: background-color var(--transition-speed-fast);
}
.dialog-button.primary {
    background-color: var(--primary-color);
    color: var(--on-primary);
}
.dialog-button.primary:hover {
    opacity: 0.9;
}
.dialog-button.secondary {
    background-color: transparent;
    color: var(--primary-color);
    border: 1px solid var(--outline-color);
}
.dialog-button.secondary:hover {
    background-color: var(--surface-container);
}
.dialog-button.danger {
    background-color: var(--danger-color);
    color: var(--on-danger);
}
.dialog-button.danger:hover {
    opacity: 0.9;
}

/* --- Dropdown Menus --- */
.dropdown {
    position: relative;
}
.dropdown-content {
    position: absolute;
    right: 0;
    top: 48px;
    background-color: var(--surface-color);
    border: 1px solid var(--surface-variant);
    border-radius: var(--border-radius-medium);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    min-width: 220px;
    z-index: 100;
    overflow: hidden;
}
.dropdown-content a {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    text-decoration: none;
    color: var(--on-surface);
    font-size: 14px;
}
.dropdown-content a:hover {
    background-color: var(--surface-container);
}
.dropdown-content a .material-symbols-outlined {
    font-size: 20px;
    color: var(--on-surface-variant);
}
#language-dropdown {
    max-height: 400px;
    overflow-y: auto;
}

/* --- Dialogs and Modals --- */
.hidden {
    display: none !important;
}
#confirmation-dialog, #new-note-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--scrim);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}
.dialog-content {
    background-color: var(--surface-color);
    padding: 24px;
    border-radius: var(--border-radius-large);
    width: 90%;
    max-width: 400px;
}
.dialog-content h3 {
    font-size: 20px;
    margin-bottom: 16px;
}
.dialog-content p {
    margin-bottom: 24px;
    color: var(--on-surface-variant);
    line-height: 1.5;
}
.dialog-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 8px;
}
#new-note-folder-select {
    width: 100%;
    padding: 12px;
    border-radius: var(--border-radius-small);
    border: 1px solid var(--outline-color);
    background-color: var(--surface-container);
    color: var(--on-surface);
    margin-bottom: 24px;
    font-size: 16px;
}

/* --- Tooltips --- */
[data-tooltip-key]::after {
    content: attr(data-tooltip-text);
    position: absolute;
    bottom: -35px;
    left: 50%;
    transform: translateX(-50%);
    background-color: #333;
    color: white;
    padding: 5px 10px;
    border-radius: var(--border-radius-small);
    font-size: 12px;
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed-fast), visibility var(--transition-speed-fast);
    z-index: 2000;
}
[data-tooltip-key]:hover::after {
    opacity: 1;
    visibility: visible;
}

/* --- File Drop Overlay --- */
#file-drop-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--scrim);
    z-index: 9999;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 4px dashed var(--primary-color);
}
.overlay-content {
    text-align: center;
    color: white;
}
.overlay-content .material-symbols-outlined {
    font-size: 80px;
}
.overlay-content p {
    font-size: 24px;
    font-weight: 500;
    margin-top: 16px;
}

/* --- Loading Spinner --- */
#loading-spinner {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--scrim);
    z-index: 10000;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: white;
}
.spinner {
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top: 4px solid #fff;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
}
#loading-text {
    margin-top: 20px;
    font-size: 18px;
}

/* --- Responsive Design --- */
.mobile-only {
    display: none;
}

@media (max-width: 768px) {
    .mobile-only {
        display: inline-flex;
    }

    .sync-status {
        display: none;
    }

    #left-panel {
        position: absolute;
        top: var(--header-height);
        left: 0;
        bottom: 0;
        width: 85%;
        max-width: 320px;
        border-right: 1px solid var(--surface-variant);
        transform: translateX(-100%);
        box-shadow: 4px 0px 15px rgba(0,0,0,0.1);
    }

    #app-container.mobile-panel-visible #left-panel {
        transform: translateX(0);
    }

    #main-content::after {
        content: '';
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        bottom: 0;
        background-color: var(--scrim);
        opacity: 0;
        visibility: hidden;
        transition: opacity var(--transition-speed-normal), visibility var(--transition-speed-normal);
        z-index: 4;
    }

    #app-container.mobile-panel-visible #main-content::after {
        opacity: 1;
        visibility: visible;
    }
}