/* ============================================
   AI Chat Website - Styles (Modernized)
   ============================================ */

:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --primary-light: #eef2ff;
    --sidebar-bg: #0f0f0f;
    --sidebar-hover: #1a1a1a;
    --sidebar-active: #262626;
    --sidebar-border: #2a2a2a;
    --main-bg: #ffffff;
    --chat-bg: #f8f9fb;
    --user-msg-bg: #4f46e5;
    --user-msg-text: #ffffff;
    --assistant-msg-bg: #ffffff;
    --assistant-msg-text: #1a1a1a;
    --border-color: #e5e7eb;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --input-bg: #ffffff;
    --input-border: #d1d5db;
    --input-focus-ring: rgba(79, 70, 229, 0.15);
    --accent-color: #4f46e5;
    --danger-color: #ef4444;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    --radius-full: 9999px;
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark mode */
body.dark-mode {
    --main-bg: #000000;
    --chat-bg: #0a0a0a;
    --user-msg-bg: #4f46e5;
    --user-msg-text: #ffffff;
    --assistant-msg-bg: #111111;
    --assistant-msg-text: #e5e7eb;
    --border-color: #1f2937;
    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --text-tertiary: #6b7280;
    --input-bg: #111111;
    --input-border: #374151;
    --input-focus-ring: rgba(79, 70, 229, 0.25);
    --sidebar-bg: #000000;
    --sidebar-hover: #111111;
    --sidebar-active: #1f2937;
    --sidebar-border: #1f2937;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
}

/* Theme transition */
body, .auth-card, .sidebar, .main-content, .chat-messages,
.message-content, .input-wrapper, .suggestion-card, .modal {
    transition: background-color 0.25s ease, color 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans SC', sans-serif;
    background: var(--main-bg);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Auth Container
   ============================================ */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 20px;
    position: relative;
    overflow: hidden;
}

.auth-container::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 30%, rgba(255,255,255,0.1) 0%, transparent 50%),
                radial-gradient(circle at 70% 70%, rgba(255,255,255,0.05) 0%, transparent 50%);
    animation: authBgFloat 20s ease-in-out infinite;
}

@keyframes authBgFloat {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(30px, -30px) rotate(1deg); }
    66% { transform: translate(-20px, 20px) rotate(-1deg); }
}

.auth-card {
    background: rgba(255, 255, 255, 0.98);
    border-radius: var(--radius-lg);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25), 0 0 0 1px rgba(255,255,255,0.1);
    padding: 48px 40px;
    width: 100%;
    max-width: 420px;
    animation: slideUp 0.5s cubic-bezier(0.16, 1, 0.3, 1);
    backdrop-filter: blur(20px);
    position: relative;
    z-index: 1;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(40px) scale(0.96);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.auth-header {
    text-align: center;
    margin-bottom: 36px;
}

.auth-header-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    color: #ffffff;
    margin: 0 auto 20px;
    box-shadow: 0 10px 15px -3px rgba(79, 70, 229, 0.3);
}

.auth-header h1 {
    font-size: 26px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.auth-header p {
    color: var(--text-secondary);
    font-size: 15px;
    font-weight: 400;
}

.form-group {
    margin-bottom: 20px;
    position: relative;
}

.form-group label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
    letter-spacing: 0.01em;
}

.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 1.5px solid var(--input-border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    transition: var(--transition);
    background: var(--input-bg);
    color: var(--text-primary);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px var(--input-focus-ring);
    background: var(--main-bg);
}

.form-group input::placeholder {
    color: var(--text-tertiary);
}

.error-message {
    background: #fef2f2;
    border: 1px solid #fecaca;
    color: var(--danger-color);
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    margin-bottom: 16px;
    font-size: 14px;
    font-weight: 500;
    animation: shake 0.4s ease;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-6px); }
    75% { transform: translateX(6px); }
}

.auth-btn {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    color: #ffffff;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    margin-top: 8px;
    box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.2);
    letter-spacing: 0.01em;
}

.auth-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(79, 70, 229, 0.3);
    background: linear-gradient(135deg, var(--primary-hover), #6d28d9);
}

.auth-btn:active {
    transform: translateY(0);
}

.auth-footer {
    text-align: center;
    margin-top: 28px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
}

.auth-footer p {
    font-size: 14px;
    color: var(--text-secondary);
}

.auth-footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

.auth-footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
    text-underline-offset: 3px;
}

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

/* ============================================
   Sidebar Overlay (Mobile)
   ============================================ */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 90;
    opacity: 0;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(2px);
}

.sidebar-overlay.active {
    opacity: 1;
}

/* ============================================
   Sidebar
   ============================================ */
.sidebar {
    width: 280px;
    background: var(--sidebar-bg);
    color: #ffffff;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--sidebar-border);
    transition: var(--transition);
    position: relative;
    z-index: 100;
}

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

.sidebar-user-area {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px;
    background: var(--sidebar-hover);
    border-radius: var(--radius-sm);
    margin-bottom: 12px;
    border: 1px solid var(--sidebar-border);
    transition: transform .35s ease, box-shadow .35s ease;
}

.sidebar-avatar {
    width: 42px;
    height: 42px;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 15px;
    font-weight: 700;
    color: #ffffff;
    flex-shrink: 0;
    box-shadow: 0 4px 10px rgba(79, 70, 229, 0.35);
    letter-spacing: 0.02em;
}

.sidebar-user-info {
    flex: 1;
    min-width: 0;
}

.sidebar-username-row {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.sidebar-username {
    font-size: 14px;
    font-weight: 600;
    color: #ffffff;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.sidebar-user-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 2px;
}

.sidebar-points {
    font-size: 12px;
    color: var(--warning-color);
    font-weight: 500;
}

.vip-badge {
    font-size: 11px;
    font-weight: 700;
    padding: 3px 10px;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, #f59e0b, #d97706);
    color: #fff;
    line-height: 1.4;
    white-space: nowrap;
    box-shadow: 0 2px 4px rgba(245, 158, 11, 0.3);
    letter-spacing: 0.02em;
}

.sidebar-user-area.vip-legendary .vip-badge {
    background: linear-gradient(135deg, #f59e0b, #ef4444);
}

.new-chat-btn {
    width: 100%;
    padding: 12px 16px;
    background: var(--primary-color);
    border: none;
    color: #ffffff;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: var(--transition);
    box-shadow: 0 4px 6px -1px rgba(79, 70, 229, 0.2);
}

.new-chat-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 6px 10px -1px rgba(79, 70, 229, 0.3);
}

.new-chat-btn:active {
    transform: translateY(0);
}

.sidebar-section {
    padding: 8px 16px;
    font-size: 11px;
    font-weight: 600;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-top: 8px;
}

.sidebar-admin-section {
    padding: 8px 16px;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.sidebar-admin-link {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 12px;
    border-radius: var(--radius-sm);
    color: #d1d5db;
    text-decoration: none;
    font-size: 13px;
    font-weight: 500;
    transition: var(--transition);
}

.sidebar-admin-link:hover {
    background: var(--sidebar-hover);
    color: #ffffff;
}

.sidebar-admin-link i {
    width: 18px;
    text-align: center;
    font-size: 13px;
    opacity: 0.7;
}

.sidebar-admin-link:hover i {
    opacity: 1;
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: 8px 12px;
}

.conversation-list {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.empty-conversations {
    padding: 32px 16px;
    text-align: center;
    color: #6b7280;
    font-size: 13px;
    line-height: 1.5;
}

.conversation-item {
    padding: 12px 14px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    position: relative;
}

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

.conversation-item.active {
    background: var(--sidebar-active);
    box-shadow: inset 3px 0 0 var(--primary-color);
}

.conversation-item.active .conversation-title {
    color: #ffffff;
    font-weight: 600;
}

.conversation-title {
    flex: 1;
    font-size: 14px;
    color: #d1d5db;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: 1.4;
}

.conversation-delete {
    opacity: 0;
    background: none;
    border: none;
    color: #6b7280;
    cursor: pointer;
    padding: 6px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    font-size: 13px;
}

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

.conversation-delete:hover {
    color: var(--danger-color);
    background: rgba(239, 68, 68, 0.15);
}

.sidebar-footer {
    padding: 16px;
    border-top: 1px solid var(--sidebar-border);
}

.model-selector {
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-bottom: 12px;
}

.model-selector label {
    font-size: 11px;
    color: #9ca3af;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.model-selector select {
    width: 100%;
    padding: 10px 12px;
    background: var(--sidebar-hover);
    border: 1px solid var(--sidebar-border);
    color: #ffffff;
    border-radius: var(--radius-sm);
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%239ca3af' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M6 9l6 6 6-6'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

.model-selector select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--input-focus-ring);
}

.effort-selector {
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-bottom: 12px;
}

.effort-selector label {
    font-size: 11px;
    color: #9ca3af;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.effort-selector select {
    width: 100%;
    padding: 10px 12px;
    background: var(--sidebar-hover);
    border: 1px solid var(--sidebar-border);
    color: #ffffff;
    border-radius: var(--radius-sm);
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%239ca3af' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M6 9l6 6 6-6'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

.effort-selector select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--input-focus-ring);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 12px;
    background: var(--sidebar-hover);
    border-radius: var(--radius-sm);
    margin-top: 4px;
}

.icon-btn {
    background: none;
    border: none;
    padding: 8px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    color: #9ca3af;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #ffffff;
}

.logout-btn {
    background: none;
    border: none;
    color: #9ca3af;
    cursor: pointer;
    padding: 8px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.logout-btn:hover {
    color: var(--danger-color);
    background: rgba(239, 68, 68, 0.15);
}

/* ============================================
   Main Content
   ============================================ */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--main-bg);
    overflow: hidden;
    min-width: 0;
}

.chat-header {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--main-bg);
    flex-shrink: 0;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 20px;
    cursor: pointer;
    color: var(--text-primary);
    padding: 8px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.mobile-menu-btn:hover {
    background: var(--assistant-msg-bg);
}

.chat-header h2 {
    flex: 1;
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    letter-spacing: -0.01em;
}

.header-actions {
    display: flex;
    gap: 4px;
}

/* ============================================
   Chat Messages
   ============================================ */
.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    background: var(--chat-bg);
    scroll-behavior: smooth;
}

.message {
    max-width: 80%;
    margin-bottom: 28px;
    animation: fadeIn 0.35s cubic-bezier(0.16, 1, 0.3, 1);
    position: relative;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.message.user {
    margin-left: auto;
}

.message.assistant {
    margin-right: auto;
}

.message-avatar {
    width: 32px;
    height: 32px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    flex-shrink: 0;
    margin-bottom: 8px;
}

.message.user .message-avatar {
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    color: #ffffff;
    margin-left: auto;
}

.message.assistant .message-avatar {
    background: #ffffff;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.message-wrapper {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.message.user .message-wrapper {
    align-items: flex-end;
}

.message.assistant .message-wrapper {
    align-items: flex-start;
}

.message-content {
    padding: 14px 18px;
    border-radius: var(--radius-lg);
    line-height: 1.65;
    font-size: 15px;
    word-wrap: break-word;
    white-space: pre-wrap;
    position: relative;
    box-shadow: var(--shadow-sm);
}

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

.message.assistant .message-content {
    background: var(--assistant-msg-bg);
    color: var(--assistant-msg-text);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 4px;
}

.message-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 11px;
    color: var(--text-tertiary);
    padding: 0 4px;
    margin-top: 4px;
}

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

.message-timestamp {
    font-weight: 500;
}

.message-actions {
    display: flex;
    gap: 4px;
    opacity: 0;
    transform: translateY(4px);
    transition: opacity 0.2s ease, transform 0.2s ease;
}

.message:hover .message-actions {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 768px) {
    .message-actions {
        opacity: 1;
        transform: translateY(0);
    }
}

.message-action-btn {
    background: none;
    border: none;
    padding: 4px 8px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    color: var(--text-tertiary);
    transition: var(--transition);
    font-size: 12px;
    display: flex;
    align-items: center;
    gap: 4px;
}

.message-action-btn:hover {
    background: var(--assistant-msg-bg);
    color: var(--text-primary);
}

/* Welcome Message */
.welcome-message {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    text-align: center;
    padding: 40px;
    animation: fadeInUp 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(24px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.welcome-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    color: #ffffff;
    margin-bottom: 24px;
    box-shadow: 0 10px 15px -3px rgba(79, 70, 229, 0.25);
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.welcome-message h1 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.welcome-message p {
    color: var(--text-secondary);
    font-size: 16px;
    margin-bottom: 32px;
    max-width: 480px;
    line-height: 1.5;
}

.suggestion-cards {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    max-width: 640px;
    width: 100%;
}

.suggestion-card {
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 16px;
    text-align: left;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: flex-start;
    gap: 12px;
    box-shadow: var(--shadow-sm);
}

.suggestion-card:hover {
    background: var(--assistant-msg-bg);
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.suggestion-card i {
    color: var(--primary-color);
    font-size: 16px;
    margin-top: 2px;
}

.suggestion-card span {
    font-size: 14px;
    color: var(--text-primary);
    line-height: 1.5;
    font-weight: 500;
}

/* ============================================
   Chat Input
   ============================================ */
.chat-input-container {
    padding: 20px 24px 28px;
    background: var(--main-bg);
    border-top: 1px solid var(--border-color);
}

.input-wrapper {
    display: flex;
    align-items: flex-end;
    gap: 10px;
    background: var(--input-bg);
    border: 1.5px solid var(--input-border);
    border-radius: var(--radius-lg);
    padding: 10px 10px 10px 18px;
    transition: var(--transition);
    max-width: 900px;
    margin: 0 auto;
    width: 100%;
    box-shadow: var(--shadow-sm);
}

.input-wrapper:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px var(--input-focus-ring), var(--shadow-md);
}

#messageInput {
    flex: 1;
    border: none;
    outline: none;
    resize: none;
    font-size: 15px;
    font-family: inherit;
    line-height: 1.5;
    max-height: 200px;
    min-height: 24px;
    background: transparent;
    color: var(--text-primary);
}

#messageInput::placeholder {
    color: var(--text-tertiary);
}

.send-btn {
    width: 42px;
    height: 42px;
    background: var(--primary-color);
    border: none;
    border-radius: var(--radius-sm);
    color: #ffffff;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    transition: var(--transition);
    flex-shrink: 0;
    box-shadow: 0 2px 4px rgba(79, 70, 229, 0.2);
}

.send-btn:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: scale(1.05);
    box-shadow: 0 4px 6px rgba(79, 70, 229, 0.3);
}

.send-btn:active:not(:disabled) {
    transform: scale(0.98);
}

.send-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    transform: none;
}

.send-btn.stop {
    background: #b91c1c;
    box-shadow: 0 2px 4px rgba(185, 28, 28, 0.35);
}

.send-btn.stop:hover {
    background: #dc2626;
    box-shadow: 0 4px 6px rgba(185, 28, 28, 0.45);
}

.attach-btn {
    width: 42px;
    height: 42px;
    background: transparent;
    border: 1.5px solid var(--input-border);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    transition: var(--transition);
    flex-shrink: 0;
}

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

.file-preview {
    max-width: 900px;
    margin: 10px auto 0;
    width: 100%;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.file-preview-item {
    position: relative;
    width: 80px;
    height: 80px;
    border-radius: var(--radius-sm);
    overflow: hidden;
    border: 1px solid var(--border-color);
    background: var(--assistant-msg-bg);
    box-shadow: var(--shadow-sm);
}

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

.file-preview-item .file-name {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.7);
    color: #fff;
    font-size: 10px;
    padding: 3px 6px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    backdrop-filter: blur(4px);
}

.file-preview-item .file-remove {
    position: absolute;
    top: 4px;
    right: 4px;
    background: rgba(0, 0, 0, 0.6);
    color: #fff;
    border: none;
    border-radius: 50%;
    width: 22px;
    height: 22px;
    font-size: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    backdrop-filter: blur(4px);
}

.file-preview-item .file-remove:hover {
    background: rgba(239, 68, 68, 0.9);
    transform: scale(1.1);
}

.input-footer {
    text-align: center;
    margin-top: 10px;
    font-size: 12px;
    color: var(--text-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
}

.input-hint-main {
    color: var(--text-secondary);
}

.input-shortcut {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 2px 8px;
    background: var(--assistant-msg-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-full);
    font-size: 11px;
    color: var(--text-tertiary);
    font-weight: 500;
}

/* ============================================
   Loading Overlay
   ============================================ */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(4px);
}

.loading-spinner {
    background: #ffffff;
    padding: 32px 48px;
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-xl);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 16px;
}

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

.loading-spinner p {
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 500;
}

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

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: #d1d5db;
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: #9ca3af;
}

.sidebar ::-webkit-scrollbar-thumb {
    background: #374151;
}

.sidebar ::-webkit-scrollbar-thumb:hover {
    background: #4b5563;
}

/* ============================================
   Mobile Bottom Navigation
   ============================================ */
.mobile-bottom-nav {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--main-bg);
    border-top: 1px solid var(--border-color);
    padding: 8px 0 max(8px, env(safe-area-inset-bottom));
    z-index: 90;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.mobile-bottom-nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-around;
}

.mobile-nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    border: none;
    background: none;
    color: var(--text-secondary);
    padding: 6px 12px;
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    min-width: 64px;
}

.mobile-nav-item i {
    font-size: 20px;
}

.mobile-nav-item span {
    font-size: 11px;
    font-weight: 500;
}

.mobile-nav-item.active {
    color: var(--primary-color);
}

.mobile-nav-item:hover {
    background: var(--assistant-msg-bg);
}

@media (max-width: 768px) {
    .mobile-bottom-nav {
        display: block;
    }

    .main-content {
        padding-bottom: calc(64px + env(safe-area-inset-bottom));
    }
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -300px;
        top: 0;
        height: 100vh;
        width: 280px;
        z-index: 100;
        transition: left 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        box-shadow: none;
    }

    .sidebar.open {
        left: 0;
        box-shadow: var(--shadow-xl);
    }

    .sidebar-overlay {
        display: block;
        pointer-events: none;
    }

    .sidebar-overlay.active {
        pointer-events: auto;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .suggestion-cards {
        grid-template-columns: 1fr;
        max-width: 100%;
    }

    .message {
        max-width: 92%;
    }

    .auth-card {
        padding: 36px 24px;
        margin: 16px;
    }

    .chat-messages {
        padding: 16px;
    }

    .chat-input-container {
        padding: 12px 16px 20px;
    }

    .input-wrapper {
        padding: 8px 8px 8px 14px;
    }

    .chat-header {
        padding: 12px 16px;
    }
}

@media (max-width: 480px) {
    .message {
        max-width: 95%;
    }

    .welcome-message {
        padding: 24px 16px;
    }

    .welcome-icon {
        width: 64px;
        height: 64px;
        font-size: 24px;
    }

    .welcome-message h1 {
        font-size: 22px;
    }

    .welcome-message p {
        font-size: 14px;
    }

    .suggestion-card {
        padding: 14px;
    }

    .sidebar {
        width: 85vw;
        max-width: 300px;
        left: calc(-85vw - 20px);
    }

    .sidebar.open {
        left: 0;
    }
}

/* ============================================
   Code Blocks
   ============================================ */
.message-content pre {
    background: #1a1a1a;
    color: #e5e7eb;
    padding: 16px;
    border-radius: var(--radius-sm);
    overflow-x: auto;
    margin: 12px 0;
    font-size: 13px;
    line-height: 1.5;
    position: relative;
}

body.dark-mode .message.assistant .message-content pre {
    background: #0a0a0a;
    border: 1px solid var(--border-color);
}

.code-block-wrapper {
    position: relative;
    margin: 12px 0;
}

.code-block-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 8px 16px;
    background: #2d2d2d;
    border-radius: var(--radius-sm) var(--radius-sm) 0 0;
    font-size: 12px;
    color: #9ca3af;
    font-weight: 500;
}

.code-copy-btn {
    background: rgba(255, 255, 255, 0.1);
    border: none;
    color: #d1d5db;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 12px;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 4px;
}

.code-copy-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #ffffff;
}

.code-copy-btn.copied {
    background: rgba(16, 185, 129, 0.2);
    color: var(--success-color);
}

.message-content code {
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', 'Consolas', monospace;
    font-size: 0.9em;
}

.message-content p {
    margin-bottom: 12px;
}

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

.message-content ul,
.message-content ol {
    margin: 12px 0;
    padding-left: 24px;
}

.message-content li {
    margin-bottom: 6px;
}

/* ============================================
   Typing Indicator
   ============================================ */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 14px 18px;
    align-items: center;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: var(--text-tertiary);
    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(-8px);
        opacity: 1;
    }
}

/* ============================================
   Modal
   ============================================ */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(4px);
    animation: fadeIn 0.2s ease;
}

.modal {
    background: var(--main-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    width: 90%;
    max-width: 520px;
    max-height: 85vh;
    overflow-y: auto;
    animation: slideUp 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 4px 8px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    line-height: 1;
}

.modal-close:hover {
    background: var(--assistant-msg-bg);
    color: var(--text-primary);
}

.modal-body {
    padding: 24px;
}

.shortcuts-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.shortcut-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.shortcut-item kbd {
    background: var(--assistant-msg-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 4px 10px;
    font-size: 12px;
    font-family: inherit;
    color: var(--text-secondary);
    min-width: 90px;
    text-align: center;
}

/* ============================================
   Music Toggle
   ============================================ */
.music-toggle {
    position: fixed;
    top: 16px;
    right: 16px;
    z-index: 80;
    width: 42px;
    height: 42px;
    border-radius: var(--radius-full);
    border: 1px solid var(--border-color);
    background: rgba(255, 255, 255, 0.7);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-sm);
    backdrop-filter: blur(10px);
    transition: var(--transition);
}

body.dark-mode .music-toggle {
    background: rgba(17, 17, 17, 0.7);
}

.music-toggle:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* ============================================
   Toast
   ============================================ */
.toast {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-primary);
    color: var(--main-bg);
    padding: 10px 16px;
    border-radius: 8px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.18);
    z-index: 9999;
    animation: fadeIn .25s ease;
}

/* Skeleton loading */
.skeleton-item {
    padding: 10px 14px;
}

.skeleton-line {
    height: 12px;
    border-radius: 6px;
    background: linear-gradient(90deg, rgba(148,163,184,0.18) 0%, rgba(148,163,184,0.34) 50%, rgba(148,163,184,0.18) 100%);
    background-size: 200% 100%;
    animation: shimmer 1.2s infinite;
}

.skeleton-title {
    width: 72%;
}

.skeleton-block {
    height: 12px;
    border-radius: 6px;
    background: linear-gradient(90deg, rgba(148,163,184,0.18) 0%, rgba(148,163,184,0.34) 50%, rgba(148,163,184,0.18) 100%);
    background-size: 200% 100%;
    animation: shimmer 1.2s infinite;
    margin-bottom: 10px;
}

.skeleton-short {
    width: 55%;
}

.message-skeleton-wrapper {
    padding: 24px 16px 16px;
    display: flex;
    flex-direction: column;
    gap: 14px;
}

@keyframes shimmer {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Conversation item base */
.conversation-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 14px;
    border-radius: 10px;
    cursor: pointer;
    transition: background .2s ease, color .2s ease;
}

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

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

.conversation-title {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-size: 14px;
}

.conversation-delete {
    opacity: 0;
    transition: opacity .2s ease;
    background: transparent;
    border: none;
    color: inherit;
    cursor: pointer;
    padding: 6px;
}

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

.sidebar-user-area.profile-highlight {
    box-shadow: 0 0 0 2px rgba(79, 70, 229, 0.45);
    transform: scale(1.01);
}