:root {
    --font-sans: 'Inter', system-ui, sans-serif;
    --bg-app: #f4f7fa;
    --bg-sidebar: #ffffff;
    --bg-chat: #ffffff;
    --bg-input: #ffffff;
    --bg-user-message: #4a80ee;
    --bg-bot-message: #eef1f5;
    --text-primary: #1a1a1a;
    --text-secondary: #6b7280;
    --text-user-message: #ffffff;
    --text-bot-message: #1a1a1a;
    --border-color: #e5e7eb;
    --accent-color: #4a80ee;
    --shadow-color: rgba(0, 0, 0, 0.05);
    --error-text: #de4437;
    --success-text: #18a34a;
}

[data-theme='dark'] {
    --bg-app: #111827;
    --bg-sidebar: #1f2937;
    --bg-chat: #111827;
    --bg-input: #374151;
    --bg-user-message: #4a80ee;
    --bg-bot-message: #374151;
    --text-primary: #f9fafb;
    --text-secondary: #9ca3af;
    --text-user-message: #ffffff;
    --text-bot-message: #f9fafb;
    --border-color: #374151;
    --accent-color: #60a5fa;
    --shadow-color: rgba(0, 0, 0, 0.2);
    --error-text: #f28b82;
    --success-text: #81c995;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-app);
    color: var(--text-primary);
    margin: 0;
    height: 100vh;
    overflow: hidden;
}

.app-layout { display: flex; height: 100%; background-color: var(--bg-app); }

#sidebar {
    width: 260px;
    background-color: var(--bg-sidebar);
    padding: 1rem;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
    transition: width 0.3s ease, padding 0.3s ease, transform 0.3s ease;
    flex-shrink: 0;
}

.app-layout.sidebar-collapsed #sidebar { width: 0; padding: 1rem 0; overflow: hidden; border-right: none; }

#sidebar-footer { margin-top: auto; border-top: 1px solid var(--border-color); padding-top: 1rem; }

#new-chat-btn, #settings-btn {
    width: 100%;
    padding: 0.75rem;
    border: none;
    border-radius: 8px;
    background-color: var(--accent-color);
    color: white;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    margin-bottom: 1rem;
    transition: background-color 0.2s;
    white-space: nowrap;
}
#settings-btn { background-color: transparent; color: var(--text-secondary); border: 1px solid var(--border-color); }
#settings-btn:hover { background-color: var(--bg-app); }

#conversation-list { list-style: none; padding: 0; margin: 0; overflow-y: auto; flex-grow: 1; }
#conversation-list li {
    position: relative; /* Needed for absolute positioning of the delete button */
    padding: 0.75rem 2rem 0.75rem 1rem; /* Add padding-right for the button */
    border-radius: 8px; 
    cursor: pointer; 
    margin-bottom: 0.5rem; 
    white-space: nowrap; 
    overflow: hidden; 
    text-overflow: ellipsis; 
    color: var(--text-secondary); 
    font-weight: 500; 
}

.delete-conv-btn {
    position: absolute;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    border: none;
    background: transparent;
    color: var(--text-secondary);
    padding: 0.25rem;
    border-radius: 4px;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.2s ease;
}

#conversation-list li:hover .delete-conv-btn {
    opacity: 1;
}

.delete-conv-btn:hover {
    background-color: var(--bg-app);
    color: var(--error-text);
}

#conversation-list li.active { background-color: var(--accent-color); color: white; }

.main-container { flex-grow: 1; display: flex; flex-direction: column; max-height: 100vh; position: relative; background-color: var(--bg-chat); }

.chat-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

#chat-title {
    margin: 0;
    font-size: 1.1rem;
    font-weight: 600;
    text-align: center;
    flex-grow: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

#model-select {
    background-color: var(--bg-input);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.4rem 0.8rem;
    font-size: 0.9rem;
}

.chat-container { flex-grow: 1; display: flex; flex-direction: column; overflow: hidden; }

.chat-box {
    flex-grow: 1;
    padding: 1.5rem;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.welcome-message { text-align: center; margin: auto; color: var(--text-secondary); }
.welcome-message h1 { font-size: 2rem; font-weight: 600; }

.message { display: flex; gap: 1rem; max-width: 85%; align-items: flex-start; }
.message .avatar { width: 36px; height: 36px; flex-shrink: 0; border-radius: 50%; display: flex; justify-content: center; align-items: center; font-weight: bold; background-color: var(--accent-color); color: white; }
.message .text-content { padding: 0.75rem 1.25rem; border-radius: 12px; line-height: 1.6; }

.user-message { align-self: flex-end; flex-direction: row-reverse; }
.user-message .text-content { background-color: var(--bg-user-message); color: var(--text-user-message); border-bottom-right-radius: 2px; }

.bot-message { align-self: flex-start; }
.bot-message .avatar { background-color: #19c37d; }
.bot-message .text-content { background-color: var(--bg-bot-message); color: var(--text-bot-message); border-bottom-left-radius: 2px; }

.error-message .text-content { background-color: var(--error-bg); color: var(--error-text); }

.chat-form { position: relative; padding: 1rem; border-top: 1px solid var(--border-color); background-color: var(--bg-input); }
#user-input { 
    width: 100%; 
    padding: 1rem 3.5rem 1rem 1.5rem; /* Add padding-right for button */
    border: 1px solid var(--border-color); 
    border-radius: 18px; 
    background-color: var(--bg-input); 
    color: var(--text-primary); 
    font-size: 1rem; 
    resize: none; 
    box-sizing: border-box;
}
#send-btn {
    position: absolute;
    right: 1.5rem;
    top: 50%;
    transform: translateY(-50%) scale(0.8);
    width: 36px;
    height: 36px;
    padding: 0;
    border: none;
    border-radius: 50%;
    background-color: var(--accent-color);
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.2s ease, transform 0.2s ease;
}

#send-btn.visible {
    opacity: 1;
    transform: translateY(-50%) scale(1);
}

#send-btn svg { width: 20px; height: 20px; }

#send-btn.generating .send-icon { display: none; }
#send-btn.generating .stop-icon { display: block; }
#send-btn:not(.generating) .send-icon { display: block; }
#send-btn:not(.generating) .stop-icon { display: none; }

/* Modal, Responsive, etc. */
.modal { display: none; position: fixed; z-index: 1000; left: 0; top: 0; width: 100%; height: 100%; background-color: rgba(0,0,0,0.5); }
.modal.active { display: flex; justify-content: center; align-items: center; }
.modal-content { background-color: var(--bg-sidebar); padding: 2rem; border-radius: 12px; width: 90%; max-width: 500px; position: relative; }
.close-btn { position: absolute; top: 1rem; right: 1.5rem; font-size: 1.5rem; font-weight: bold; cursor: pointer; }

.setting-item { margin-bottom: 1.5rem; }
.setting-item label { display: block; margin-bottom: 0.5rem; font-weight: 500; }
.setting-item input, .setting-item select { width: 100%; padding: 0.5rem 0.75rem; border: 1px solid var(--border-color); border-radius: 8px; font-size: 0.9rem; background-color: var(--bg-input); color: var(--text-primary); box-sizing: border-box; }
.checkbox-label { display: flex; align-items: center; cursor: pointer; }
.checkbox-label input[type="checkbox"] { margin-right: 0.5rem; cursor: pointer; width: auto; }
.checkbox-label span { font-weight: normal; }
#api-key-status { margin-top: 0.5rem; font-size: 0.85rem; min-height: 1.2em; }
.status-success { color: var(--success-text); }
.status-error { color: var(--error-text); }

.theme-switcher { display: flex; justify-content: space-between; align-items: center; }
.switch { position: relative; display: inline-block; width: 50px; height: 28px; }
.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; }
.slider:before { position: absolute; content: ""; height: 20px; width: 20px; left: 4px; bottom: 4px; background-color: white; transition: .4s; }
input:checked + .slider { background-color: var(--accent-color); }
input:checked + .slider:before { transform: translateX(22px); }
.slider.round { border-radius: 34px; }
.slider.round:before { border-radius: 50%; }

#delete-all-btn { width: 100%; padding: 0.75rem; border: 1px solid var(--error-text); color: var(--error-text); background: transparent; border-radius: 8px; cursor: pointer; }

#sidebar-toggle-btn {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 40px;
    height: 40px;
    background: transparent;
    color: var(--text-secondary);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

#sidebar-toggle-btn:hover {
    background-color: var(--bg-bot-message);
}

/* Markdown Styles */
.text-content pre {
    background-color: var(--bg-app);
    padding: 1rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    white-space: pre-wrap;
    word-wrap: break-word;
}

.text-content code {
    font-family: 'Courier New', Courier, monospace;
    background-color: var(--bg-app);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-size: 0.9rem;
}

.text-content pre code {
    background-color: transparent;
    padding: 0;
    border-radius: 0;
    font-size: inherit;
}

.text-content ul, .text-content ol {
    padding-left: 1.5rem;
}

.text-content blockquote {
    border-left: 3px solid var(--accent-color);
    padding-left: 1rem;
    margin-left: 0;
    font-style: italic;
    color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 768px) {
    #sidebar { position: fixed; height: 100%; z-index: 1001; transform: translateX(-100%); }
    .app-layout.sidebar-open #sidebar { transform: translateX(0); }
    /* The button is now always visible, so this rule is not needed anymore */
    .app-layout.sidebar-collapsed #sidebar { transform: translateX(-100%); }
}
/* =================================================================
   CSS ĐÃ CÓ VÀ ĐÃ LÀM ĐÚNG THEO YÊU CẦU CỦA BẠN
   ================================================================= */

/* Styles cho media trong chat */
.content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.media-content {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.chat-media {
    max-width: 200px;
    max-height: 200px;
    border-radius: 8px;
    cursor: pointer;
    object-fit: cover;
}

video.chat-media {
    cursor: default;
}

/* Style cho nút upload */
#upload-btn {
    position: absolute;
    left: 1.5rem;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
    transition: background-color 0.2s;
}

#upload-btn:hover {
    background-color: var(--bg-bot-message);
}

/* Điều chỉnh padding cho input để tránh chồng lên nút upload */
#user-input {
    padding-left: 3.5rem !important;
}

/* Styles cho file preview */
#file-preview {
    padding: 8px;
    border-bottom: 1px solid var(--border-color);
}

.preview-files {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.preview-item {
    position: relative;
    width: 100px;
    height: 100px;
    border-radius: 8px;
    overflow: hidden;
    background-color: var(--bg-bot-message);
}

.preview-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-preview {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 8px;
    box-sizing: border-box;
}

.video-preview svg {
    width: 32px;
    height: 32px;
    margin-bottom: 4px;
}

.video-preview span {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-align: center;
    word-break: break-word;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.remove-file {
    position: absolute;
    top: 4px;
    right: 4px;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background-color: rgba(0, 0, 0, 0.5);
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    padding: 0;
    line-height: 1;
}

.remove-file:hover {
    background-color: rgba(0, 0, 0, 0.7);
}

/* Styles cho drag & drop */
#user-input.drag-over {
    border-color: var(--accent-color);
    background-color: var(--bg-bot-message);
}

/* Animation cho preview */
.preview-item {
    animation: fadeIn 0.3s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Wrapper để định vị nút copy, KHÔNG CUỘN */
.code-wrapper {
    position: relative;
    margin-top: 1em;
    margin-bottom: 1em;
    /* Đảm bảo không có overflow trên wrapper này */
    /* overflow: hidden;  <-- KHÔNG DÙNG CÁI NÀY NẾU KHÔNG CẦN THIẾT */
}

/* Khối <pre> bên trong, có thể CUỘN */
.code-wrapper pre {
    max-height: 300px; /* Ví dụ: Giới hạn chiều cao để khối code có thể cuộn dọc */
    overflow: auto;    /* Quan trọng: Tạo thanh cuộn khi nội dung vượt quá kích thước */
    /* overflow-x: auto; nếu chỉ muốn cuộn ngang */
    /* overflow-y: auto; nếu chỉ muốn cuộn dọc */

    padding-top: 2.5em !important; /* Đủ chỗ cho nút copy */
    margin: 0 !important;
    background-color: #2d2d2d; /* Ví dụ màu nền cho code */
    color: #f8f8f2;
    padding: 1.2em;
    border-radius: 6px;
}

/* Nút Copy, cố định trong wrapper, KHÔNG CUỘN cùng nội dung pre */
.copy-btn {
    position: absolute; /* Quan trọng: Đặt tuyệt đối trong .code-wrapper */
    top: 8px;
    right: 8px;
    display: flex;
    align-items: center;
    gap: 6px;
    background-color: #3e434e;
    color: #e0e0e0;
    border: 1px solid #555;
    padding: 6px 10px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    opacity: 0;
    transition: opacity 0.2s ease-in-out, background-color 0.2s ease-in-out;
    z-index: 10; /* Đảm bảo nút nằm trên code nếu có trường hợp che phủ */
}

/* Các style khác cho nút và hover */
.code-wrapper:hover .copy-btn {
    opacity: 1;
}

.copy-btn:hover {
    background-color: #555c69;
}

.copy-btn.copied {
    background-color: #28a745;
    color: white;
    opacity: 1;
}