/* ============================================
   CSS Custom Properties (Theme Variables)
   ============================================ */

:root {
    /* Colors - Light Theme */
    --color-bg: #ffffff;
    --color-bg-secondary: #f5f5f5;
    --color-bg-tertiary: #e8e8e8;
    --color-text: #1a1a1a;
    --color-text-secondary: #4a4a4a;
    --color-text-muted: #888888;
    --color-border: #e0e0e0;
    --color-border-light: #f0f0f0;
    
    /* Brand Colors */
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-primary-light: #dbeafe;
    --color-danger: #dc2626;
    --color-danger-hover: #b91c1c;
    --color-success: #16a34a;
    --color-warning: #f59e0b;
    
    /* Message Colors */
    --color-user-bg: #2563eb;
    --color-user-text: #ffffff;
    --color-assistant-bg: #f5f5f5;
    --color-assistant-text: #1a1a1a;
    
    /* Sizing */
    --sidebar-width: 280px;
    --header-height: 60px;
    --input-height: 120px;
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Z-Index Scale */
    --z-header: 100;
    --z-backdrop: 900;
    --z-sidebar: 1000;
    --z-modal: 2000;
    --z-toast: 3000;
}

/* Dark Theme */
[data-theme="dark"] {
    --color-bg: #0f0f0f;
    --color-bg-secondary: #1a1a1a;
    --color-bg-tertiary: #262626;
    --color-text: #f5f5f5;
    --color-text-secondary: #d4d4d4;
    --color-text-muted: #737373;
    --color-border: #2d2d2d;
    --color-border-light: #262626;
    
    --color-primary-light: #1e3a5f;
    
    --color-user-bg: #2563eb;
    --color-user-text: #ffffff;
    --color-assistant-bg: #1a1a1a;
    --color-assistant-text: #f5f5f5;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
}

/* ============================================
   Reset & Base Styles
   ============================================ */

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-bg);
    overflow: hidden;
}

/* Accessibility */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

.text-muted {
    color: var(--color-text-muted);
}

/* ============================================
   App Layout
   ============================================ */

.app {
    display: flex;
    height: 100vh;
    height: 100dvh;
    overflow: hidden;
}

/* ============================================
   Sidebar
   ============================================ */

.sidebar {
    width: var(--sidebar-width);
    height: 100%;
    background: var(--color-bg-secondary);
    border-right: 1px solid var(--color-border);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    transition: transform var(--transition-normal), width var(--transition-normal);
    z-index: var(--z-sidebar);
    overflow: hidden;
}

.sidebar.collapsed {
    transform: translateX(-100%);
    width: 0;
    border: none;
}

.sidebar__header {
    padding: 1rem;
    border-bottom: 1px solid var(--color-border);
}

.sidebar__conversations {
    flex: 1;
    overflow-y: auto;
    padding: 0.5rem;
}

.sidebar__empty {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--color-text-muted);
}

.sidebar__empty p:first-child {
    font-weight: 500;
    margin-bottom: 0.25rem;
}

.sidebar__footer {
    padding: 1rem;
    border-top: 1px solid var(--color-border);
}

/* Conversation Item */
.conversation-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background var(--transition-fast);
    margin-bottom: 0.125rem;
}

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

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

.conversation-item__title {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-size: 0.875rem;
}

.conversation-item {
    min-height: 44px;
}

.conversation-item__delete {
    opacity: 0;
    transition: opacity var(--transition-fast);
    width: 28px !important;
    height: 28px !important;
}

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

/* Sidebar Toggle */
.sidebar-toggle {
    position: fixed;
    top: 0.5rem;
    left: 0.5rem;
    z-index: calc(var(--z-header) + 1);
    width: 44px;
    height: 44px;
    border-radius: var(--radius-md);
    background: transparent;
    border: none;
    color: var(--color-text);
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    transition: background var(--transition-fast);
}

.sidebar-toggle:hover {
    background: var(--color-bg-tertiary);
}

/* Sidebar Backdrop */
.sidebar-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: var(--z-backdrop);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), visibility var(--transition-normal);
    backdrop-filter: blur(2px);
}

.sidebar-backdrop.visible {
    opacity: 1;
    visibility: visible;
}

/* ============================================
   Main Chat Area
   ============================================ */

.chat {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
    background: var(--color-bg);
}

/* Chat Header */
.chat__header {
    height: var(--header-height);
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg);
    flex-shrink: 0;
}

.chat__title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    min-width: 0;
}

.chat__title h1 {
    font-size: 1.125rem;
    font-weight: 600;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.chat__actions {
    display: flex;
    gap: 0.5rem;
}

/* Status Bar */
.status-bar {
    padding: 0.75rem 1.5rem;
    background: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    flex-shrink: 0;
}

.status-bar__content {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.status-bar__icon {
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.status-bar.ready .status-bar__icon {
    color: var(--color-success);
}

.status-bar.error .status-bar__icon {
    color: var(--color-danger);
}

#status-text {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

/* Progress */
.progress-container {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex: 1;
    max-width: 300px;
}

.progress {
    flex: 1;
    height: 6px;
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress__bar {
    height: 100%;
    background: var(--color-primary);
    border-radius: var(--radius-full);
    transition: width var(--transition-fast);
}

.progress__text {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-text-muted);
    min-width: 3rem;
    text-align: right;
}

/* Messages Container */
.chat__messages {
    flex: 1;
    overflow-y: auto;
    position: relative;
}

.message-list {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

/* Welcome Screen */
.welcome {
    text-align: center;
    padding: 3rem 1rem;
    max-width: 500px;
    margin: 0 auto;
}

.welcome__icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 1.5rem;
    color: var(--color-primary);
}

.welcome__icon svg {
    width: 100%;
    height: 100%;
}

.welcome h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.welcome > p {
    color: var(--color-text-secondary);
    margin-bottom: 1.5rem;
}

.welcome__features {
    list-style: none;
    text-align: left;
    display: inline-block;
    margin-bottom: 1.5rem;
}

.welcome__features li {
    padding: 0.5rem 0;
    color: var(--color-text-secondary);
}

/* Message Bubbles */
.message {
    display: flex;
    flex-direction: column;
    max-width: 85%;
    animation: fadeIn var(--transition-normal);
}

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

.message--user {
    align-self: flex-end;
}

.message--assistant {
    align-self: flex-start;
}

/* Comparison Mode Group */
.message-group {
    display: flex;
    gap: 1rem;
    width: 100%;
    align-self: stretch;
}

.message-group .message {
    flex: 1;
    max-width: none;
    min-width: 0;
    width: 0;
}

.message__bubble {
    padding: 0.875rem 1rem;
    border-radius: var(--radius-lg);
    line-height: 1.6;
}

.message--user .message__bubble {
    background: var(--color-user-bg);
    color: var(--color-user-text);
    border-bottom-right-radius: var(--radius-sm);
}

.message--assistant .message__bubble {
    background: var(--color-assistant-bg);
    color: var(--color-assistant-text);
    border-bottom-left-radius: var(--radius-sm);
    border: 1px solid var(--color-border);
}

/* Code Block Wrapper */
.code-block {
    margin: 0.75rem 0;
    border-radius: var(--radius-md);
    overflow: hidden;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
}

.code-block__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.5rem 1rem;
    background: rgba(0, 0, 0, 0.2);
    border-bottom: 1px solid var(--color-border);
    font-size: 0.75rem;
    color: var(--color-text-muted);
}

.code-block pre {
    margin: 0 !important;
    border-radius: 0 !important;
    background: transparent !important;
}

/* Copy Buttons */
.btn-copy-code {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.btn-copy-code:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--color-text);
}

.btn-copy-message {
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: var(--radius-sm);
    opacity: 0; /* Hide by default */
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.message:hover .btn-copy-message {
    opacity: 1;
}

.btn-copy-message:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text);
}

.btn-edit-message {
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: var(--radius-sm);
    opacity: 0; /* Hide by default */
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.message:hover .btn-edit-message {
    opacity: 1;
}

.btn-edit-message:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text);
}

.btn-copy-code.success,
.btn-copy-message.success {
    color: var(--color-success);
}

/* Edit Form */
.edit-form {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    width: 100%;
}

.edit-form__textarea {
    width: 100%;
    padding: 0.5rem;
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-text);
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    resize: none;
}

.edit-form__textarea:focus {
    outline: none;
    border-color: var(--color-primary);
}

.edit-form__actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
}

.message__meta {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0.375rem;
    padding: 0 0.25rem;
    min-height: 24px;
}

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

.message__time {
    font-size: 0.75rem;
    color: var(--color-text-muted);
}

.message__model {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    background: var(--color-bg-tertiary);
    padding: 0.125rem 0.5rem;
    border-radius: var(--radius-sm);
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 0.5rem;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: var(--color-text-muted);
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out both;
}

.typing-indicator span:nth-child(1) { animation-delay: -0.32s; }
.typing-indicator span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}

/* Scroll to Bottom Button */
.scroll-bottom-btn {
    position: absolute;
    bottom: 1rem;
    right: 1rem;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    color: var(--color-text);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-fast);
}

.scroll-bottom-btn:hover {
    background: var(--color-bg-tertiary);
    transform: translateY(-2px);
}

/* Input Area */
.chat__input-area {
    padding: 1rem 1.5rem;
    padding-bottom: calc(1rem + env(safe-area-inset-bottom));
    border-top: 1px solid var(--color-border);
    background: var(--color-bg);
    flex-shrink: 0;
}

.model-controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 0.75rem;
    flex-wrap: wrap;
}

.model-selector {
    display: flex;
    gap: 0.75rem;
    flex: 1;
    min-width: 280px;
}

.model-selector .select {
    flex: 1;
}

.input-group {
    display: flex;
    gap: 0.5rem;
    align-items: flex-end;
}

.input-group__textarea {
    flex: 1;
    min-height: 44px;
    max-height: 200px;
    padding: 0.75rem 1rem;
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.5;
    color: var(--color-text);
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    resize: none;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.input-group__textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-light);
}

.input-group__textarea:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.input-group__textarea::placeholder {
    color: var(--color-text-muted);
}

.chat__disclaimer {
    text-align: center;
    font-size: 0.75rem;
    color: var(--color-text-muted);
    margin-top: 0.5rem;
}

/* ============================================
   Components
   ============================================ */

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.625rem 1rem;
    font-family: inherit;
    font-size: 0.875rem;
    font-weight: 500;
    line-height: 1;
    text-decoration: none;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn.active {
    background: var(--color-primary-light);
    color: var(--color-primary);
}

.btn--primary {
    background: var(--color-primary);
    color: white;
}

.btn--primary:hover:not(:disabled) {
    background: var(--color-primary-hover);
}

.btn--danger {
    background: var(--color-danger);
    color: white;
}

.btn--danger:hover:not(:disabled) {
    background: var(--color-danger-hover);
}

.btn--ghost {
    background: transparent;
    color: var(--color-text);
}

.btn--ghost:hover:not(:disabled) {
    background: var(--color-bg-tertiary);
}

.btn--outline {
    background: transparent;
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn--outline:hover:not(:disabled) {
    background: var(--color-bg-secondary);
    border-color: var(--color-text-muted);
}

.btn--full {
    width: 100%;
}

.btn--icon {
    width: 44px;
    height: 44px;
    padding: 0;
}

.btn--sm {
    padding: 0.375rem 0.75rem;
    font-size: 0.8125rem;
}

/* Select */
.select {
    padding: 0.625rem 2rem 0.625rem 0.75rem;
    font-family: inherit;
    font-size: 0.875rem;
    color: var(--color-text);
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%23888' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.5rem center;
    transition: border-color var(--transition-fast);
}

.select:focus {
    outline: none;
    border-color: var(--color-primary);
}

.select:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Textarea */
.textarea {
    width: 100%;
    padding: 0.75rem;
    font-family: inherit;
    font-size: 0.875rem;
    line-height: 1.5;
    color: var(--color-text);
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    resize: vertical;
    transition: border-color var(--transition-fast);
}

.textarea:focus {
    outline: none;
    border-color: var(--color-primary);
}

/* Slider */
.slider {
    width: 100%;
    height: 6px;
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
    appearance: none;
    cursor: pointer;
}

.slider::-webkit-slider-thumb {
    width: 18px;
    height: 18px;
    background: var(--color-primary);
    border-radius: 50%;
    appearance: none;
    cursor: pointer;
    transition: transform var(--transition-fast);
}

.slider::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

.slider::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: var(--color-primary);
    border: none;
    border-radius: 50%;
    cursor: pointer;
}

/* Badge */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.625rem;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-full);
    background: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
}

.badge--model {
    background: var(--color-primary-light);
    color: var(--color-primary);
}

/* Icon */
.icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

/* Spinner */
.spinner {
    width: 18px;
    height: 18px;
    border: 2px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ============================================
   Modal
   ============================================ */

.modal {
    position: fixed;
    inset: 0;
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    background: rgba(0, 0, 0, 0.1);
    color: var(--color-text);
    border: none;
    border-radius: var(--radius-xl);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), visibility var(--transition-normal);
}

.modal[open] {
    opacity: 1;
    visibility: visible;
}

.modal::backdrop {
    background: transparent;
}

.modal__content {
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    background: var(--color-bg);
    color: var(--color-text);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.modal__content--sm {
    max-width: 400px;
}

.modal__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
}

.modal__header h2 {
    font-size: 1.125rem;
    font-weight: 600;
}

.modal__body {
    padding: 1.5rem;
    overflow-y: auto;
}

/* Settings */
.setting {
    margin-bottom: 1.5rem;
}

.setting:last-child {
    margin-bottom: 0;
}

.setting__label {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.setting__value {
    font-weight: 600;
    color: var(--color-primary);
}

.setting__control {
    margin-bottom: 0.375rem;
}

.setting__help {
    font-size: 0.8125rem;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
}

.setting__actions {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.setting--danger {
    padding-top: 1.5rem;
    border-top: 1px solid var(--color-border);
}

.setting--danger .setting__label {
    color: var(--color-danger);
}

/* Export Options */
.export-options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 1rem;
}

/* Shortcuts Modal */
.shortcuts-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.shortcut-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--color-border);
}

.shortcut-item:last-child {
    border-bottom: none;
}

.shortcut-desc {
    font-size: 0.875rem;
    color: var(--color-text);
}

.shortcut-key {
    font-family: inherit;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.25rem 0.5rem;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    min-width: 24px;
    text-align: center;
    display: inline-block;
}

/* ============================================
   Toast Notifications
   ============================================ */

.toast-container {
    position: fixed;
    bottom: 1.5rem;
    right: 1.5rem;
    z-index: var(--z-toast);
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.toast {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.875rem 1rem;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    animation: slideIn var(--transition-normal);
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.toast--success {
    border-left: 3px solid var(--color-success);
}

.toast--error {
    border-left: 3px solid var(--color-danger);
}

.toast--warning {
    border-left: 3px solid var(--color-warning);
}

.toast__message {
    font-size: 0.875rem;
}

/* ============================================
   Theme Toggle Icons
   ============================================ */

[data-theme="dark"] .icon--sun {
    display: block;
}

[data-theme="dark"] .icon--moon {
    display: none;
}

[data-theme="light"] .icon--sun,
:root:not([data-theme="dark"]) .icon--sun {
    display: none;
}

[data-theme="light"] .icon--moon,
:root:not([data-theme="dark"]) .icon--moon {
    display: block;
}

/* ============================================
   Markdown Content Styles
   ============================================ */

.message__bubble p {
    margin-bottom: 0.75rem;
}

.message__bubble p:last-child {
    margin-bottom: 0;
}

.message__bubble code {
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    font-size: 0.875em;
    padding: 0.125rem 0.375rem;
    background: rgba(0, 0, 0, 0.1);
    border-radius: var(--radius-sm);
}

[data-theme="dark"] .message__bubble code {
    background: rgba(255, 255, 255, 0.1);
}

.message__bubble pre {
    margin: 0.75rem 0;
    border-radius: var(--radius-md);
    overflow: hidden;
}

.message__bubble pre code {
    font-size: 0.8125rem;
    line-height: 1.6;
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
}

/* Override highlight.js background to match theme if needed, 
   but for now we let the library theme take precedence */
.hljs {
    padding: 1rem !important; /* Ensure consistent padding */
}

.message__bubble ul,
.message__bubble ol {
    margin: 0.75rem 0;
    padding-left: 1.5rem;
}

.message__bubble li {
    margin-bottom: 0.375rem;
}

.message__bubble blockquote {
    margin: 0.75rem 0;
    padding-left: 1rem;
    border-left: 3px solid var(--color-border);
    color: var(--color-text-secondary);
}

.message__bubble a {
    color: var(--color-primary);
    text-decoration: underline;
}

/* Streaming cursor */
.message__bubble .cursor {
    display: inline-block;
    animation: blink 1s step-end infinite;
    color: var(--color-primary);
    font-weight: normal;
}

@keyframes blink {
    50% { opacity: 0; }
}

.message__bubble h1,
.message__bubble h2,
.message__bubble h3 {
    margin: 1rem 0 0.5rem;
    font-weight: 600;
}

.message__bubble h1:first-child,
.message__bubble h2:first-child,
.message__bubble h3:first-child {
    margin-top: 0;
}

/* Error Message in Bubble */
.message__bubble--error {
    background: var(--color-bg-secondary) !important;
    border: 1px solid var(--color-danger) !important;
    color: var(--color-danger) !important;
}

.error-message {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.error-message__content {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
}

.error-message .btn-retry {
    align-self: flex-start;
    color: var(--color-text);
    border-color: var(--color-border);
}

.error-message .btn-retry:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
    background: var(--color-primary-light);
}

/* ============================================
   Responsive Design
   ============================================ */

@media (max-width: 768px) {
    .sidebar,
    .sidebar.collapsed {
        position: fixed;
        left: 0;
        top: 0;
        height: 100%;
        transform: translateX(-100%);
        box-shadow: var(--shadow-xl);
        width: var(--sidebar-width) !important;
    }
    
    .sidebar.mobile-open {
        transform: translateX(0);
    }

    .sidebar-toggle {
        display: flex;
    }
    
    .chat__header {
        padding-left: 3.5rem;
    }
    
    .chat__title h1 {
        font-size: 1rem;
    }
    
    .message-list {
        padding: 1rem;
    }
    
    .message {
        max-width: 95%;
    }
    
    .chat__input-area {
        padding: 0.75rem 1rem;
    }
    
    .model-selector {
        flex-direction: column;
    }
    
    .toast-container {
        left: 1rem;
        right: 1rem;
        bottom: 1rem;
    }
    
    .toast {
        width: 100%;
    }

    /* Hide header actions on mobile */
    #compare-toggle,
    #export-btn {
        display: none !important;
    }
}

/* Extra small devices */
@media (max-width: 600px) {
    .chat__header {
        padding-left: 4rem;
        padding-right: 0.75rem;
    }

    .chat__title {
        overflow: hidden;
    }

    .chat__title h1 {
        font-size: 1rem;
    }

    /* Hide badge on very small screens to prevent overlap */
    .chat__title .badge {
        display: none !important;
    }

    .chat__actions {
        gap: 0.25rem;
    }

    .chat__actions .btn {
        padding: 0.5rem;
    }

    .model-selector .select {
        font-size: 0.8125rem;
        padding-top: 0.5rem;
        padding-bottom: 0.5rem;
    }

    .model-selector .btn {
        padding: 0.5rem 0.75rem;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}