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

:root {
    /* Light Theme */
    --bg-primary: #f5f7fb;
    --bg-secondary: #ffffff;
    --bg-sidebar: rgba(255, 255, 255, 0.95);
    --text-primary: #1a1a2e;
    --text-secondary: #666;
    --border-color: rgba(0, 0, 0, 0.08);
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(255, 255, 255, 0.8);
    --accent-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --accent-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
    --message-user: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --message-assistant: #ffffff;
    --scrollbar-track: #f1f1f1;
    --scrollbar-thumb: #c1c1c1;
}

[data-theme="dark"] {
    --bg-primary: #0f0f1a;
    --bg-secondary: #1a1a2e;
    --bg-sidebar: rgba(26, 26, 46, 0.95);
    --text-primary: #ffffff;
    --text-secondary: #a0a0c0;
    --border-color: rgba(255, 255, 255, 0.08);
    --glass-bg: rgba(26, 26, 46, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.4);
    --message-user: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --message-assistant: #2a2a3e;
    --scrollbar-track: #1a1a2e;
    --scrollbar-thumb: #3a3a5e;
}

/* Theme Variants */
[data-theme="ocean"] {
    --bg-primary: #e8f4f8;
    --bg-secondary: #ffffff;
    --accent-primary: linear-gradient(135deg, #006994, #004e7c);
    --message-user: linear-gradient(135deg, #006994, #004e7c);
}

[data-theme="forest"] {
    --bg-primary: #e8f5e9;
    --bg-secondary: #ffffff;
    --accent-primary: linear-gradient(135deg, #2e7d32, #1b5e20);
    --message-user: linear-gradient(135deg, #2e7d32, #1b5e20);
}

[data-theme="sunset"] {
    --bg-primary: #fff3e0;
    --bg-secondary: #ffffff;
    --accent-primary: linear-gradient(135deg, #ff6b6b, #ee5a24);
    --message-user: linear-gradient(135deg, #ff6b6b, #ee5a24);
}

[data-theme="midnight"] {
    --bg-primary: #0a0e27;
    --bg-secondary: #131b3c;
    --text-primary: #e0e0ff;
    --accent-primary: linear-gradient(135deg, #667eea, #764ba2);
    --message-user: linear-gradient(135deg, #667eea, #764ba2);
    --message-assistant: #1a2352;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    overflow: hidden;
    transition: background 0.3s ease, color 0.3s ease;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: var(--scrollbar-track);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: #667eea;
}

/* App Container */
.app-container {
    display: flex;
    height: 100vh;
    width: 100%;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--bg-sidebar);
    backdrop-filter: blur(20px);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    z-index: 10;
    flex-shrink: 0;
}

.sidebar.collapsed {
    width: 60px;
}

.sidebar.collapsed .logo-area h2,
.sidebar.collapsed .new-chat-btn span,
.sidebar.collapsed .import-chat-btn span,
.sidebar.collapsed .search-btn span,
.sidebar.collapsed .settings-btn span,
.sidebar.collapsed .conversation-info,
.sidebar.collapsed .lang-toggle span {
    display: none;
}

.sidebar.collapsed .new-chat-btn,
.sidebar.collapsed .import-chat-btn,
.sidebar.collapsed .search-btn,
.sidebar.collapsed .settings-btn {
    justify-content: center;
    padding: 10px;
}

.sidebar.collapsed .conversation-item {
    justify-content: center;
    padding: 10px;
}

.sidebar-header {
    padding: 20px 16px;
    border-bottom: 1px solid var(--border-color);
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
}

.logo-icon {
    width: 36px;
    height: 36px;
    background: var(--accent-primary);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

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

.logo-area h2 {
    font-size: 1.2rem;
    font-weight: 700;
    background: var(--accent-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Sidebar Buttons */
.new-chat-btn,
.import-chat-btn,
.search-btn,
.settings-btn {
    width: 100%;
    padding: 10px 12px;
    margin-bottom: 8px;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-primary);
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: all 0.2s;
}

.new-chat-btn {
    background: var(--accent-primary);
    color: white;
    border: none;
}

.new-chat-btn:hover,
.import-chat-btn:hover,
.search-btn:hover,
.settings-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

/* Conversations List */
.conversations-list {
    flex: 1;
    overflow-y: auto;
    padding: 12px;
}

.conversation-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.2s;
    margin-bottom: 4px;
}

.conversation-item:hover {
    background: var(--glass-bg);
}

.conversation-item.active {
    background: var(--accent-primary);
    color: white;
}

.conversation-info {
    flex: 1;
    overflow: hidden;
}

.conversation-title {
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    cursor: pointer;
}

.conversation-title:hover {
    text-decoration: underline;
}

.conversation-date {
    font-size: 0.65rem;
    opacity: 0.6;
}

.conversation-delete {
    opacity: 0;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 4px 6px;
    border-radius: 6px;
    transition: all 0.2s;
}

.conversation-item:hover .conversation-delete {
    opacity: 1;
}

.conversation-delete:hover {
    background: rgba(220, 53, 69, 0.2);
    color: #dc3545;
}

/* Sidebar Footer */
.sidebar-footer {
    padding: 16px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    gap: 8px;
}

.sidebar-footer button {
    flex: 1;
    padding: 8px;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    color: var(--text-primary);
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.sidebar-footer button:hover {
    background: var(--accent-primary);
    color: white;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    min-width: 0;
}

/* Chat Header */
.chat-header {
    padding: 12px 20px;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 20px;
    cursor: pointer;
    color: var(--text-primary);
}

.header-info {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}

.provider-badge {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    background: var(--accent-primary);
    border-radius: 20px;
    color: white;
    font-size: 0.75rem;
    font-weight: 600;
}

.model-selector select,
.mode-selector select {
    padding: 6px 12px;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    color: var(--text-primary);
    cursor: pointer;
    font-size: 0.8rem;
}

.clear-chat-btn {
    background: none;
    border: none;
    font-size: 18px;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 6px;
    border-radius: 8px;
    transition: all 0.2s;
}

.clear-chat-btn:hover {
    background: rgba(220, 53, 69, 0.1);
    color: #dc3545;
}

/* Welcome Screen */
.welcome-screen {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px;
    overflow-y: auto;
}

.welcome-content {
    text-align: center;
    max-width: 500px;
}

.static-logo {
    width: 100px;
    height: 100px;
    margin: 0 auto 24px;
}

.logo-icon-center {
    width: 100%;
    height: 100%;
    background: var(--accent-primary);
    border-radius: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.logo-icon-center img {
    width: 70%;
    height: 70%;
    object-fit: contain;
    filter: brightness(0) invert(1);
}

.welcome-content h1 {
    font-size: 2rem;
    margin-bottom: 12px;
    background: var(--accent-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
}

/* Chat Messages */
.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.message {
    display: flex;
    animation: fadeIn 0.3s ease;
}

.message.user {
    justify-content: flex-end;
}

.message.assistant {
    justify-content: flex-start;
}

.message-content {
    max-width: 75%;
    padding: 10px 16px;
    border-radius: 18px;
    line-height: 1.4;
    font-size: 0.9rem;
}

.message.user .message-content {
    background: var(--message-user);
    color: white;
    border-bottom-right-radius: 4px;
}

.message.assistant .message-content {
    background: var(--message-assistant);
    color: var(--text-primary);
    border-bottom-left-radius: 4px;
    box-shadow: var(--shadow-sm);
}

/* Input Area */
.input-area {
    padding: 16px 20px;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border-top: 1px solid var(--border-color);
}

.input-container {
    display: flex;
    gap: 10px;
    align-items: flex-end;
}

.input-container textarea {
    flex: 1;
    padding: 10px 14px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.9rem;
    resize: none;
    transition: all 0.2s;
    max-height: 120px;
    overflow-y: auto;
    scrollbar-width: thin;
}

/* Textarea scrollbar styling - no scroll on single line */
.input-container textarea::-webkit-scrollbar {
    width: 4px;
}

.input-container textarea::-webkit-scrollbar-track {
    background: transparent;
}

.input-container textarea::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 4px;
}

.input-container textarea:focus {
    outline: none;
    border-color: #667eea;
}

.send-btn {
    width: 38px;
    height: 38px;
    background: var(--accent-primary);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    color: white;
    font-size: 14px;
    transition: transform 0.2s;
    flex-shrink: 0;
}

.send-btn:hover {
    transform: translateY(-1px);
}

.input-footer {
    margin-top: 6px;
    font-size: 0.65rem;
    color: var(--text-secondary);
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 4px 0;
}

.typing-indicator span {
    width: 6px;
    height: 6px;
    background: var(--accent-primary);
    border-radius: 50%;
    animation: typing 1.4s infinite;
}

.typing-indicator span:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-indicator span:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.4;
    }
    30% {
        transform: translateY(-6px);
        opacity: 1;
    }
}

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

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(8px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    max-width: 450px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    border-radius: 20px;
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-lg);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

.modal-close {
    background: none;
    border: none;
    font-size: 22px;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.modal-close:hover {
    transform: rotate(90deg);
}

.modal-body {
    padding: 20px;
}

/* Language Options */
.lang-option {
    width: 100%;
    padding: 10px 14px;
    margin: 6px 0;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    cursor: pointer;
    font-size: 0.9rem;
    text-align: left;
    transition: all 0.2s;
    color: var(--text-primary);
}

.lang-option:hover {
    background: var(--accent-primary);
    color: white;
    transform: translateX(4px);
}

/* Settings Section */
.settings-section {
    margin-bottom: 20px;
}

.settings-section h4 {
    margin-bottom: 10px;
    font-size: 0.9rem;
}

.settings-section label {
    font-size: 0.8rem;
    display: block;
    margin-bottom: 6px;
    color: var(--text-secondary);
}

.settings-section select {
    width: 100%;
    padding: 8px 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-primary);
    font-size: 0.85rem;
}

.theme-options {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.theme-option {
    padding: 6px 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.8rem;
    color: var(--text-primary);
}

.theme-option:hover {
    background: var(--accent-primary);
    color: white;
}

.settings-action-btn {
    width: 100%;
    margin-top: 10px;
    padding: 8px;
    background: var(--accent-primary);
    border: none;
    border-radius: 10px;
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 0.85rem;
}

/* Search Modal */
.search-input {
    width: 100%;
    padding: 10px 14px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    color: var(--text-primary);
    font-size: 0.9rem;
    margin-bottom: 16px;
}

.search-results {
    max-height: 300px;
    overflow-y: auto;
}

.search-result-item {
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
    transition: all 0.2s;
}

.search-result-item:hover {
    background: var(--glass-bg);
}

.search-result-title {
    font-weight: 600;
    font-size: 0.85rem;
}

.search-result-preview {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 4px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Notification */
.notification {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 10px 20px;
    background: var(--accent-primary);
    color: white;
    border-radius: 10px;
    font-size: 0.8rem;
    z-index: 1100;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.3s ease;
    pointer-events: none;
}

.notification.show {
    opacity: 1;
    transform: translateY(0);
}

.notification.error {
    background: linear-gradient(135deg, #dc3545, #c82333);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -280px;
        height: 100vh;
        z-index: 100;
        width: 280px;
    }
    
    .sidebar.mobile-open {
        left: 0;
    }
    
    .sidebar.collapsed {
        left: -60px;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .message-content {
        max-width: 85%;
    }
    
    .welcome-content h1 {
        font-size: 1.5rem;
    }
    
    .static-logo {
        width: 70px;
        height: 70px;
    }
    
    .header-info {
        gap: 8px;
    }
    
    .model-selector select,
    .mode-selector select {
        font-size: 0.7rem;
        padding: 4px 8px;
    }
}