/* --- 1. Root Variables & Global Styles --- */
        :root {
            --font-family-sans: 'Google Sans', 'Noto Sans SC', sans-serif;
            
            /* Light Theme Palette */
            --bg-main: #f0f4f9;
            --bg-sidebar: #e6eaf1;
            --bg-content: #ffffff;
            --bg-input: #f0f4f9;
            --bg-input-focus: #e8eef4;
            --bg-hover-light: #d3e3fd;
            --bg-hover-dark: #dde3ea;
            --bg-active-item: #c2e7ff;
            --bg-ultra-badge: #e8e8e8;
            --bg-send-button: #297FE5; 
            --bg-send-button-hover: #1A73E8;
            --bg-modal-backdrop: rgba(0, 0, 0, 0.4);

            --text-primary: #1f1f1f;
            --text-secondary: #444746;
            --text-placeholder: #5f6368;
            --text-on-dark-bg: #ffffff;
            --text-ultra-badge: #1f1f1f;
            --text-link: #0b57d0;

            --border-color: #d8dde3;
            --border-active: #0b57d0;
            
            --message-model-bg: linear-gradient(135deg, #f5f5f5, #ffffff);
            --message-user-bg: linear-gradient(135deg, #e9e9e9, #f7f7f7);
            --thinking-animation-bg: linear-gradient(90deg, #e9e9e9, #f7f7f7, #e9e9e9);
            --new-chat-btn-bg: var(--bg-main);
            --new-chat-btn-hover-bg: #f8fafd;
            --scrollbar-thumb-bg: #d6d6d6;
            --temp-slider-thumb-border: var(--bg-content);

            --sidebar-width: 256px;
            --header-height: 64px;

            --transition-speed-fast: 0.2s;
            --transition-speed-normal: 0.3s;
            --transition-easing: cubic-bezier(0.4, 0, 0.2, 1);
        }

        body.dark-mode {
            /* Dark Theme Palette */
            --bg-main: #131314;
            --bg-sidebar: #1e1f20;
            --bg-content: #131314;
            --bg-input: #2d2e30;
            --bg-input-focus: #3c3d3f;
            --bg-hover-light: #3c3d3f;
            --bg-hover-dark: #28292a;
            --bg-active-item: #04395e;
            --bg-ultra-badge: #3c3d3f;
            --bg-send-button: #89b4e4; 
            --bg-send-button-hover: #93c5fd;
            --bg-modal-backdrop: rgba(0, 0, 0, 0.6);

            --text-primary: #e3e3e3;
            --text-secondary: #969ba1;
            --text-placeholder: #7f8287;
            --text-on-dark-bg: #131314;
            --text-ultra-badge: #e3e3e3;
            --text-link: #89b4e4;

            --border-color: #3c3d3f;
            --border-active: #89b4e4;

            --message-model-bg: linear-gradient(135deg, #2a2b2d, #1e1f20);
            --message-user-bg: linear-gradient(135deg, #2d2e30, #232425);
            --thinking-animation-bg: linear-gradient(90deg, #2a2b2d, #3c3d3f, #2a2b2d);
            --new-chat-btn-bg: var(--bg-input);
            --new-chat-btn-hover-bg: #3c3d3f;
            --scrollbar-thumb-bg: #4a4c4e;
            --temp-slider-thumb-border: var(--bg-input);
        }


        *, *::before, *::after {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            -webkit-tap-highlight-color: transparent;
        }

        html, body {
            height: 100%;
            width: 100%;
            overflow: hidden;
        }

        body {
            font-family: var(--font-family-sans);
            color: var(--text-primary);
            background-color: var(--bg-main);
            display: flex;
            transition: background-color var(--transition-speed-normal) ease;
        }

        button, input, textarea {
            font-family: inherit;
        }

        svg {
            width: 24px;
            height: 24px;
            flex-shrink: 0;
            color: var(--text-secondary);
        }
        
        .icon-button {
            display: flex;
            align-items: center;
            justify-content: center;
            width: 48px;
            height: 48px;
            background: none;
            border: none;
            border-radius: 50%;
            cursor: pointer;
            transition: background-color var(--transition-speed-fast) ease;
        }
        .icon-button:hover {
            background-color: var(--bg-input);
        }
        .icon-button:disabled {
            opacity: 0.5;
            cursor: not-allowed;
            background-color: transparent;
        }

        /* --- 2. Main Layout & Sidebar --- */
        .app-container {
            display: flex;
            width: 100%;
            height: 100%;
            position: relative;
        }

        #sidebar-backdrop {
            display: none;
            position: fixed;
            top: 0; left: 0; width: 100%; height: 100%;
            background-color: var(--bg-modal-backdrop);
            z-index: 199;
            opacity: 0;
            pointer-events: none;
            transition: opacity var(--transition-speed-normal) ease;
        }
        .app-container:not(.sidebar-collapsed) #sidebar-backdrop {
            display: block;
            opacity: 1;
            pointer-events: auto;
        }

        #sidebar {
            width: var(--sidebar-width);
            height: 100%;
            background-color: var(--bg-sidebar);
            display: flex;
            flex-direction: column;
            padding: 16px 12px;
            flex-shrink: 0;
            position: absolute;
            top: 0;
            left: 0;
            transform: translateX(0);
            transition: transform var(--transition-speed-normal) var(--transition-easing), background-color var(--transition-speed-normal) ease;
            z-index: 200;
            box-shadow: 4px 0 15px -5px rgba(0,0,0,0.1);
        }

        .app-container.sidebar-collapsed #sidebar {
            transform: translateX(-100%); 
            box-shadow: none;
        }
        
        .main-content-area {
            flex-grow: 1;
            height: 100%;
            transition: margin-left var(--transition-speed-normal) var(--transition-easing);
            margin-left: var(--sidebar-width);
        }

        .app-container.sidebar-collapsed .main-content-area {
            margin-left: 0;
        }
        
        @media (max-width: 1024px) {
             #sidebar {
                width: 280px;
             }
        }

        @media (max-width: 768px) {
            body {
                zoom: 0.85;
            }
            .main-content-area {
                margin-left: 0 !important;
            }
            #sidebar {
                width: 85%;
                max-width: 320px;
            }
        }


        .sidebar-header {
            margin-bottom: 16px;
            padding: 0 4px;
        }

        #new-chat-btn {
            display: flex;
            align-items: center;
            justify-content: space-between;
            width: 100%;
            height: 52px;
            padding: 0 24px 0 4px;
            background-color: var(--new-chat-btn-bg);
            border: none;
            border-radius: 26px;
            font-size: 1rem;
            font-weight: 500;
            color: var(--text-primary);
            cursor: pointer;
            transition: all var(--transition-speed-fast) ease;
            box-shadow: 0 1px 2px rgba(0,0,0,0.1);
        }
        #new-chat-btn:hover {
            box-shadow: 0 2px 8px rgba(0,0,0,0.15);
            background-color: var(--new-chat-btn-hover-bg);
        }
        
        #new-chat-btn .icon-placeholder {
            width: 44px;
            height: 44px;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        #history-list {
            flex-grow: 1;
            overflow-y: auto;
            padding-right: 4px;
        }
        #history-list::-webkit-scrollbar {
            width: 6px;
        }
        #history-list::-webkit-scrollbar-track {
            background: transparent;
            margin: 4px 0;
        }
        #history-list::-webkit-scrollbar-thumb {
            background-color: #a0a8b3;
            border-radius: 6px;
            border: 1px solid var(--bg-sidebar);
        }
        #history-list::-webkit-scrollbar-thumb:hover {
            background-color: #858e9c;
        }

        .history-item {
            display: flex;
            align-items: center;
            justify-content: space-between;
            width: 100%;
            padding: 12px 16px;
            border-radius: 24px;
            cursor: pointer;
            transition: background-color var(--transition-speed-fast) ease;
            margin-bottom: 4px;
        }
        .history-item:hover {
            background-color: var(--bg-hover-dark);
        }
        .history-item.active {
            background-color: var(--bg-active-item);
            font-weight: 500;
        }
        .history-item-title {
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;
            font-size: 0.9rem;
        }
        .delete-chat-btn {
            background: none; border: none; cursor: pointer;
            opacity: 0; transition: opacity var(--transition-speed-fast) ease;
            display: flex; align-items: center; justify-content: center;
            width: 32px;
            height: 32px;
            border-radius: 50%;
        }
        .delete-chat-btn svg {
            width: 18px;
            height: 18px;
        }
        .history-item:hover .delete-chat-btn {
            opacity: 0.7;
        }
        .delete-chat-btn:hover {
            opacity: 1;
            background-color: rgba(0,0,0,0.1);
        }

        #sidebar-footer {
            position: relative;
            padding: 0 4px;
        }
        
        #settings-button {
            display: flex;
            align-items: center;
            justify-content: center;
            width: 44px;
            height: 44px;
            border-radius: 50%;
            cursor: pointer;
            transition: background-color var(--transition-speed-fast) ease, transform var(--transition-speed-normal) ease;
        }
        #settings-button:hover {
            background-color: var(--bg-hover-dark);
            transform: rotate(90deg);
        }
        
        #settings-menu {
            position: absolute;
            bottom: 100%;
            left: 0;
            width: 100%;
            margin-bottom: 8px;
            background-color: var(--bg-content);
            border-radius: 12px;
            padding: 8px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.15);
            z-index: 1001;
            visibility: hidden;
            opacity: 0;
            transform: translateY(10px) scale(0.95);
            transition: all var(--transition-speed-fast) ease, background-color var(--transition-speed-normal) ease;
        }
        #settings-menu.active {
            visibility: visible;
            opacity: 1;
            transform: translateY(0) scale(1);
        }
        .settings-menu-item {
            display: flex;
            align-items: center;
            gap: 12px;
            padding: 12px;
            border-radius: 8px;
            cursor: pointer;
            font-size: 0.9rem;
            transition: background-color var(--transition-speed-fast) ease;
        }
        .settings-menu-item:hover {
            background-color: var(--bg-hover-dark);
        }


        /* --- 3. Main Content Area --- */
        .chat-area {
            width: 100%;
            height: 100%;
            background-color: var(--bg-content);
            display: grid;
            grid-template-rows: var(--header-height) 1fr auto;
            position: relative;
            transition: background-color var(--transition-speed-normal) ease;
        }

        /* --- 4. Header --- */
        .chat-header {
            grid-row: 1;
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0 24px;
            flex-shrink: 0;
            background: transparent;
        }

        .header-left, .header-right {
            display: flex;
            align-items: center;
            gap: 16px;
        }

        .header-title-group {
            display: flex;
            align-items: center;
            gap: 8px;
        }
        .header-title-group h1 {
            font-size: 1.375rem;
            font-weight: 500;
            color: var(--text-primary);
        }

        .model-selector-wrapper {
            position: relative;
        }

        .selected-model {
            display: flex;
            align-items: center;
            gap: 6px;
            padding: 8px 12px;
            border-radius: 8px;
            cursor: pointer;
            transition: background-color var(--transition-speed-fast) ease;
        }
        .selected-model:hover {
            background-color: var(--bg-input);
        }
        #selected-model-display {
            font-size: 1.375rem;
            font-weight: 400;
            color: var(--text-secondary);
        }
        .selected-model svg {
            width: 20px;
            height: 20px;
        }

        .model-dropdown {
            position: absolute;
            top: calc(100% + 8px);
            left: 0;
            background-color: var(--bg-content);
            border-radius: 12px;
            padding: 8px;
            box-shadow: 0 4px 16px rgba(0,0,0,0.15);
            z-index: 1000;
            width: 320px;
            visibility: hidden;
            opacity: 0;
            transform: translateY(10px) scale(0.95);
            transition: all var(--transition-speed-fast) ease, background-color var(--transition-speed-normal) ease;
        }
        .model-dropdown.active {
            visibility: visible;
            opacity: 1;
            transform: translateY(0) scale(1);
        }
        .model-option h4 { font-weight: 500; }
        .model-option p { font-size: 0.8rem; color: var(--text-secondary); }
        .checkmark { color: var(--text-link); }

        .ultra-badge {
            background-color: var(--bg-ultra-badge);
            color: var(--text-ultra-badge);
            font-size: 0.8rem;
            font-weight: 700;
            padding: 6px 12px;
            border-radius: 8px;
            letter-spacing: 0.5px;
            transition: background-color var(--transition-speed-normal) ease, color var(--transition-speed-normal) ease;
        }

        /* --- 5. Chat Output --- */
        .chat-output-wrapper {
            grid-row: 2;
            overflow: hidden;
            position: relative;
        }
        .chat-output-wrapper::before {
            content: '';
            position: absolute;
            left: 0;
            right: 0;
            height: 30px;
            pointer-events: none;
            z-index: 2;
            top: 0;
            background: linear-gradient(to bottom, var(--bg-content), transparent);
            transition: background var(--transition-speed-normal) ease;
        }
        .chat-output-wrapper::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            right: 0;
            height: 40px;
            pointer-events: none;
            z-index: 2;
            background: linear-gradient(to top, var(--bg-content), transparent);
            transition: background var(--transition-speed-normal) ease;
            display: block;
        }

        #chatOutput {
            height: 100%;
            overflow-y: auto;
            padding: 0 24px 16px 24px;
        }
        #chatOutput::-webkit-scrollbar { width: 8px; }
        #chatOutput::-webkit-scrollbar-track { background: transparent; }
        #chatOutput::-webkit-scrollbar-thumb {
            background-color: var(--scrollbar-thumb-bg);
            border-radius: 10px;
            border: 2px solid var(--bg-content);
            transition: background-color var(--transition-speed-normal) ease;
        }

        .chat-content-container {
            max-width: 800px;
            margin: 0 auto;
            display: flex;
            flex-direction: column;
            gap: 24px;
            height: 100%;
        }
        
        @keyframes floatIn {
            from {
                opacity: 0;
                transform: translateY(15px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }
        
        @keyframes fadeIn {
            from { opacity: 0; }
            to { opacity: 1; }
        }

        .message.fade-in-whole, .message.content-refreshed {
            animation: floatIn 0.5s var(--transition-easing) forwards;
        }

        @keyframes thinking-gradient {
            0% { background-position: 0% 50%; }
            50% { background-position: 100% 50%; }
            100% { background-position: 0% 50%; }
        }

        .message-wrapper {
            animation: floatIn 0.5s var(--transition-easing);
            display: flex;
            flex-direction: column;
        }
        .message-wrapper.user {
            align-items: flex-end;
        }
        .message-wrapper.model {
            align-items: flex-start;
        }
        .message-wrapper:hover .message-actions {
            opacity: 1;
            transform: translateY(0);
        }

        .chat-content-container > .message-wrapper:last-of-type {
            margin-bottom: 45vh;
        }

        .welcome-container {
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            height: 100%;
            text-align: center;
        }
        .welcome-message {
            flex-grow: 0;
        }
        .welcome-message h2 {
            font-size: 3.5rem;
            font-weight: 500;
            background: linear-gradient(45deg, #2196F3, #E91E63, #2196F3);
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
            animation: floatIn 0.7s var(--transition-easing) forwards, gradient-animation 8s ease infinite;
            background-size: 200% 200%;
        }
        
        @keyframes gradient-animation {
            0% { background-position: 0% 50%; }
            50% { background-position: 100% 50%; }
            100% { background-position: 0% 50%; }
        }

        .message {
            max-width: 100%;
            padding: 1rem 1.25rem;
            border-radius: 20px;
            line-height: 1.6;
            word-wrap: break-word;
            position: relative;
            box-shadow: 0 2px 5px rgba(0,0,0,0.05);
            transition: background var(--transition-speed-normal) ease, color var(--transition-speed-normal) ease;
        }
        .message.is-editing {
            border: 2px solid var(--border-active);
            box-shadow: 0 0 0 4px var(--bg-hover-light);
            padding: 0;
            background: var(--bg-input-focus);
        }
        .message.thinking-animation {
            color: var(--text-secondary);
            font-style: italic;
            background: var(--thinking-animation-bg);
            background-size: 200% 200%;
            animation: thinking-gradient 2.5s ease infinite;
        }

        .message-wrapper.model .message {
            border-top-left-radius: 4px;
            background: var(--message-model-bg);
            color: var(--text-primary);
        }
        .message-wrapper.user .message {
            background: var(--message-user-bg);
            color: var(--text-primary);
            border-bottom-right-radius: 4px;
        }
        .message p:not(:last-child) {
            margin-bottom: 1em;
        }
        .message ul, .message ol {
            padding-left: 1.5em;
        }
        .message pre {
            background-color: #1e1e1e; color: #d4d4d4; padding: 16px;
            border-radius: 8px; position: relative;
            margin: 1em 0;
            white-space: pre-wrap;
            word-wrap: break-word;
        }
        .message code { font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace; font-size: 14px; }
        .copy-code-button {
            position: absolute; top: 10px; right: 10px; background-color: #555; color: white;
            border: none; padding: 5px 10px; border-radius: 5px; cursor: pointer; opacity: 0;
            transition: opacity var(--transition-speed-fast);
        }
        .message pre:hover .copy-code-button { opacity: 1; }
        .copy-code-button:hover { background-color: #666; }
        
        .message-actions {
            display: flex;
            flex-wrap: wrap;
            gap: 8px;
            opacity: 0;
            transition: opacity var(--transition-speed-fast) ease, transform var(--transition-speed-fast) ease;
        }
        .message-wrapper.model .message-actions {
            margin-bottom: 8px;
            transform: translateY(5px);
        }
        .message-wrapper.user .message-actions {
            display: flex !important;
            opacity: 1 !important;
            transform: translateY(0) !important;
            transition: opacity 0.2s ease, transform 0.2s ease;
            margin-top: 8px;
            justify-content: flex-end; /* 按钮右对齐 */
        }
                .message-wrapper.user:hover .message-actions {
            opacity: 1;
            transform: translateY(0);
        }
        
        .action-button {
            background-color: var(--bg-content);
            border: 1px solid var(--border-color);
            border-radius: 16px;
            padding: 4px 12px;
            font-size: 0.8rem;
            cursor: pointer;
            display: flex;
            align-items: center;
            gap: 4px;
            box-shadow: 0 1px 3px rgba(0,0,0,0.05);
            transition: all var(--transition-speed-fast) ease;
            color: var(--text-primary);
        }
        body.dark-mode .action-button {
            color: #fff;
        }
         .action-button:hover {
            background-color: var(--bg-input);
         }
         .action-button svg {
            width: 16px; height: 16px;
            color: currentColor;
         }
         .action-button.regenerate-button svg {
            width: 18px; height: 18px;
         }
        
        @keyframes loading-gradient {
            0% { background-color: rgba(60, 61, 63, 0.5); }
            50% { background-color: rgba(80, 81, 83, 0.6); }
            100% { background-color: rgba(60, 61, 63, 0.5); }
        }

        #summarize-btn {
            gap: 8px;
            padding: 8px 16px;
            width: auto;
            height: auto;
        }
        #summarize-btn svg {
            width: 18px; height: 18px;
        }
        
        .rewrite-options {
            display: flex;
            gap: 8px;
            opacity: 0;
            visibility: hidden;
            transform: translateY(-5px);
            transition: opacity 0.2s ease, visibility 0s 0.2s, transform 0.2s ease;
        }
        .rewrite-options.visible {
            opacity: 1;
            visibility: visible;
            transform: translateY(0);
            transition: opacity 0.2s ease, visibility 0s 0s, transform 0.2s ease;
        }
        .message-loading-overlay {
            position: absolute;
            top: 0; left: 0; right: 0; bottom: 0;
            color: white;
            display: flex;
            align-items: center;
            justify-content: center;
            border-radius: 20px;
            z-index: 10;
            font-size: 0.9rem;
            font-weight: 500;
            animation: fadeIn 0.3s ease, loading-gradient 2s ease-in-out infinite;
        }


        /* --- 6. Chat Input Area --- */
        .chat-input-area {
            grid-row: 3;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 0 24px 0 24px;
            flex-direction: column;
            background: transparent;
        }
        .chat-input-container {
            width: 100%;
            max-width: 800px;
            position: relative;
            margin-top: 12px;
        }
        .chat-input {
            display: flex;
            align-items: center;
            gap: 8px;
            width: 100%;
            min-height: 56px;
            background-color: var(--bg-input);
            border-radius: 28px;
            padding: 8px 12px;
            transition: background-color var(--transition-speed-normal) ease;
            box-shadow: 0 2px 8px rgba(0,0,0,0.08);
        }
        .chat-input:focus-within {
            background-color: var(--bg-input-focus);
        }

        #userInput {
            flex-grow: 1;
            border: none;
            background: transparent;
            font-size: 1rem;
            line-height: 1.5;
            outline: none;
            color: var(--text-primary);
            resize: none;
            overflow-y: hidden;
            padding: 8px 0;
            max-height: 125px; 
            scrollbar-width: none; 
        }
        #userInput::-webkit-scrollbar {
            display: none; 
        }
        #userInput::placeholder {
            color: var(--text-placeholder);
        }
        
        /* NEW: Yuki Mode Button Styles */
        #yuki-mode-btn {
            display: flex;
            align-items: center;
            justify-content: center;
            width: 40px;
            height: 40px;
            flex-shrink: 0;
            background: transparent;
            border: none;
            border-radius: 50%;
            cursor: pointer;
            padding: 0;
            transition: background-color 0.2s ease, color 0.2s ease;
        }
        #yuki-mode-btn:hover:not(.active):not(:disabled) {
            background-color: var(--bg-input-focus);
        }
        #yuki-mode-btn.active {
            background-color: var(--bg-hover-light);
        }
        #yuki-mode-btn.active svg {
            color: var(--text-link);
        }
        #yuki-mode-btn:disabled {
            cursor: not-allowed;
            opacity: 0.9;
        }
        body.dark-mode #yuki-mode-btn.active {
            background-color: var(--bg-active-item);
        }
        body.dark-mode #yuki-mode-btn:hover:not(.active):not(:disabled) {
            background-color: var(--bg-input-focus);
        }


        #sendButton {
            display: flex;
            align-items: center;
            justify-content: center;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            border: none;
            background-color: var(--bg-send-button);
            cursor: pointer;
            transition: all var(--transition-speed-fast) ease;
            transform: scale(0);
            opacity: 0;
            flex-shrink: 0;
        }
        #sendButton svg {
            color: var(--text-on-dark-bg);
        }
        #sendButton:hover:not(:disabled) {
            background-color: var(--bg-send-button-hover);
            transform: scale(1.05);
        }
        #sendButton:disabled {
            opacity: 0.5;
            cursor: not-allowed;
        }
        #sendButton.visible {
            transform: scale(1);
            opacity: 1;
        }
        #sendButton.hidden-by-edit {
            transform: scale(0);
            opacity: 0;
        }
        #sendButton .stop-icon { display: none; }
        #sendButton.is-loading .send-icon { display: none; }
        #sendButton.is-loading .stop-icon { display: block; }
        #sendButton.is-loading { background-color: #dc3545; }

        .disclaimer-text {
            text-align: center;
            font-size: 0.75rem;
            color: var(--text-secondary);
            padding: 12px 1rem;
            background: transparent;
        }

        /* --- 7. Modals --- */
        .modal-overlay {
            position: fixed; top: 0; left: 0; width: 100%; height: 100%;
            background-color: var(--bg-modal-backdrop);
            z-index: 2000;
            display: flex; justify-content: center; align-items: center;
            opacity: 0;
            visibility: hidden;
            transition: opacity var(--transition-speed-normal) ease, visibility 0s var(--transition-speed-normal);
        }
        .modal-overlay.active {
            opacity: 1;
            visibility: visible;
            transition: opacity var(--transition-speed-normal) ease;
        }
        .modal-content {
            background-color: var(--bg-content);
            padding: 24px;
            border-radius: 16px;
            width: 90%;
            max-width: 500px;
            box-shadow: 0 8px 24px rgba(0,0,0,0.1);
            transform: scale(0.95);
            opacity: 0;
            transition: transform var(--transition-speed-normal) var(--transition-easing), opacity var(--transition-speed-normal) ease, background-color var(--transition-speed-normal) ease;
        }
        .modal-overlay.active .modal-content {
            transform: scale(1);
            opacity: 1;
        }
        .modal-content.content-fade-in {
            animation: fadeIn 0.4s ease forwards;
        }

        .modal-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; }
        .modal-title { font-size: 1.25rem; font-weight: 500; }
        .modal-close-btn { background: none; border: none; font-size: 1.5rem; cursor: pointer; color: var(--text-secondary); }
        .modal-intro { color: var(--text-secondary); margin-bottom: 24px; font-size: 0.9rem; line-height: 1.5; }
        .modal-intro b { color: var(--text-primary); font-weight: 500; }
        
        #modal-title { margin-bottom: 8px; }
        #modal-message { margin-bottom: 16px; color: var(--text-secondary); white-space: pre-wrap; max-height: 60vh; overflow-y: auto;}
        #modal-input-wrapper { margin-bottom: 24px; }
        #modal-input { width: 100%; padding: 12px; border: 1px solid var(--border-color); border-radius: 8px; font-size: 1rem; background-color: var(--bg-input); color: var(--text-primary); }
        #modal-input:focus { border-color: var(--border-active); outline: none; box-shadow: 0 0 0 2px var(--bg-hover-light); }
        #modal-button-wrapper { display: flex; justify-content: flex-end; gap: 8px; }
        .modal-btn { padding: 10px 24px; border-radius: 20px; border: none; font-size: 0.9rem; font-weight: 500; cursor: pointer; transition: background-color var(--transition-speed-fast) ease; }
        #modal-confirm-btn { background-color: var(--text-link); color: var(--text-on-dark-bg); }
        body.light-mode #modal-confirm-btn { color: white; }
        #modal-confirm-btn:hover { background-color: #0a4cb0; }
        body.dark-mode #modal-confirm-btn:hover { background-color: #93c5fd; }
        #modal-cancel-btn { background-color: transparent; color: var(--text-link); }
        #modal-cancel-btn:hover { background-color: var(--bg-hover-light); }

        .switch { position: relative; display: inline-block; width: 44px; height: 24px; }
        .switch input { opacity: 0; width: 0; height: 0; }
        .slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: #ccc; transition: .4s; border-radius: 24px; }
        .slider:before { position: absolute; content: ""; height: 18px; width: 18px; left: 3px; bottom: 3px; background-color: white; transition: .4s; border-radius: 50%; }
        input:checked + .slider { background-color: var(--text-link); }
        input:checked + .slider:before { transform: translateX(20px); }

        .custom-preset-container { margin-top: 16px; }
        .custom-preset-toggle-wrapper { display: flex; justify-content: space-between; align-items: center; margin-bottom: 12px; }
        #custom-preset-input { width: 100%; min-height: 100px; padding: 12px; border-radius: 8px; border: 1px solid var(--border-color); resize: vertical; background-color: var(--bg-input); color: var(--text-primary); }
        .options-list { display: flex; flex-direction: column; gap: 16px; }
        .option-item { display: flex; justify-content: space-between; align-items: center; }
        .option-item p.jieshao { color: var(--text-secondary); font-size: 0.8rem; }
        
        #temperature-slider {
            -webkit-appearance: none;
            appearance: none;
            flex-grow: 1;
            max-width: 150px;
            height: 6px;
            background: var(--bg-hover-dark);
            border-radius: 3px;
            outline: none;
            cursor: pointer;
            transition: all var(--transition-speed-fast) ease;
        }
        #temperature-slider:hover {
            opacity: 0.9;
        }
        #temperature-slider::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 18px;
            height: 18px;
            background: var(--text-link);
            border-radius: 50%;
            border: 3px solid var(--temp-slider-thumb-border);
            box-shadow: 0 1px 4px rgba(0,0,0,0.2);
            margin-top: -6px;
            transition: transform var(--transition-speed-fast) ease;
        }
        #temperature-slider:hover::-webkit-slider-thumb,
        #temperature-slider:focus::-webkit-slider-thumb {
             transform: scale(1.1);
        }
        #temperature-slider::-moz-range-thumb {
            width: 18px;
            height: 18px;
            background: var(--text-link);
            border-radius: 50%;
            border: 3px solid var(--temp-slider-thumb-border);
            box-shadow: 0 1px 4px rgba(0,0,0,0.2);
            cursor: pointer;
        }

        /* --- 8. Responsiveness --- */
        @media (max-width: 768px) {
            .chat-header { padding: 0 16px; }
            .header-title-group h1, #selected-model-display { font-size: 1.25rem; }
            .welcome-message h2 { font-size: 2.5rem; text-align: center; }
            .chat-input-area { padding: 8px 16px 12px 16px; }
            #chatOutput { padding: 16px; }
            .header-right { gap: 4px; }
            .message-wrapper.user .message-actions {display: flex !important;opacity: 1 !important;}
            .message-actions {
                opacity: 1;
                transform: translateY(0)!important;
            }
            .delete-chat-btn {
                opacity: 0.7;
            }
        }
        .edit-button {
    margin-left: auto; /* 使按钮靠右 */
}

/* ==========================================================================
   === 9. Custom Styling for Attachments, Account and Login Pages ===
   ========================================================================== */

/* --- File Chips / Attachments Styling --- */
.file-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  width: 100%;
  max-width: 800px;
  margin-top: 8px;
  padding: 0 16px;
}

.file-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background-color: var(--bg-sidebar);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 4px 10px;
  font-size: 0.8rem;
  color: var(--text-primary);
  animation: floatIn 0.3s var(--transition-easing);
}

.file-chip button {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  transition: background-color var(--transition-speed-fast) ease, color var(--transition-speed-fast) ease;
}

.file-chip button:hover {
  background-color: var(--bg-input-focus);
  color: var(--text-primary);
}

/* Error text style under the input bar */
.error-text {
  color: #d93025; /* Google-like red */
  font-size: 0.8rem;
  margin-top: 6px;
  text-align: center;
  width: 100%;
}
body.dark-mode .error-text {
  color: #f28b82;
}

/* --- Account & Login Pages Styling --- */
.account-shell {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: var(--bg-main);
  color: var(--text-primary);
  padding: 24px;
  transition: background-color var(--transition-speed-normal) ease;
}

.account-layout {
  width: min(800px, 100%);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.account-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 16px;
}

.account-header h1 {
  margin: 0;
  font-size: 1.8rem;
  font-weight: 500;
  color: var(--text-primary);
}

.account-header p {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.account-nav {
  display: flex;
  gap: 12px;
}

.endpoint-panel,
.key-actions,
.new-key,
.keys-table-wrap,
.curl-panel {
  border: 1px solid var(--border-color);
  background: var(--bg-content);
  border-radius: 12px;
  padding: 18px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.04);
}

.endpoint-panel label,
.new-key label,
.curl-panel label {
  display: block;
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 500;
  margin-bottom: 8px;
}

.endpoint-panel code,
.new-key code,
.curl-panel code {
  font-family: monospace;
  word-break: break-all;
  font-size: 0.9rem;
  background-color: var(--bg-main);
  padding: 4px 8px;
  border-radius: 6px;
}

.keys-table-wrap {
  overflow-x: auto;
}

.keys-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.keys-table th,
.keys-table td {
  text-align: left;
  padding: 12px 10px;
  border-bottom: 1px solid var(--border-color);
}

.keys-table th {
  color: var(--text-secondary);
  font-weight: 500;
}

.keys-table td {
  color: var(--text-primary);
}

.curl-panel pre {
  margin: 0;
  white-space: pre-wrap;
  word-break: break-all;
}

.auth-card {
  width: min(480px, 100%);
  border: 1px solid var(--border-color);
  background: var(--bg-content);
  border-radius: 16px;
  padding: 28px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.auth-card h1 {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--text-primary);
}

.auth-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.5;
}

/* Button styles in account page to match oxygen7.xyz styles */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: background-color var(--transition-speed-fast) ease, transform var(--transition-speed-fast) ease;
  border: none;
  text-decoration: none;
}

.button.primary {
  background-color: var(--bg-send-button);
  color: var(--text-on-dark-bg);
}
body.light-mode .button.primary {
  color: white;
}
.button.primary:hover {
  background-color: var(--bg-send-button-hover);
}

.button.secondary {
  background-color: var(--bg-input);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}
.button.secondary:hover {
  background-color: var(--bg-input-focus);
}

.button.ghost {
  background-color: transparent;
  color: var(--text-link);
}
.button.ghost:hover {
  background-color: var(--bg-hover-light);
}

.hidden {
  display: none !important;
}