:root {
    /* Color Palette - Premium Lavender Academic Theme */
    --bg-color: #FDFEFE;
    /* White with a hint of cool */
    --surface-color: #FFFFFF;
    --text-primary: #1F1635;
    /* Dark Deep Violet */
    --text-secondary: #6D6875;
    /* Muted Plum */
    --accent-color: #8B5CF6;
    /* Vibrant Lavender */
    --accent-soft: #F5F3FF;
    /* Soft Lavender tint */

    /* Message Bubble Colors */
    --user-bubble: linear-gradient(135deg, #8B5CF6 0%, #7C3AED 100%);
    --user-text: #FFFFFF;
    /* White text for contrast */
    --assistant-bubble: #F8F9FA;
    /* Neutral gray-white */
    --assistant-text: #1F1635;
    /* Deep Violet */

    --border-color: #E9E4ED;
    /* Very Light Plum */
    --input-bg: #FFFFFF;

    /* Advanced Shadows */
    --shadow-soft: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
    --shadow-premium: 0 10px 25px -5px rgba(139, 92, 246, 0.1), 0 8px 10px -6px rgba(139, 92, 246, 0.05);
    --shadow-bubble: 0 4px 15px rgba(139, 92, 246, 0.15);

    /* Spacing & Sizing */
    --radius-lg: 20px;
    --radius-md: 12px;
    --radius-sm: 8px;
    --max-width-chat: 900px;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

html {
    height: 100%;
    height: -webkit-fill-available;
}

body {
    background-color: var(--bg-color);
    background-image:
        radial-gradient(at 0% 0%, hsla(262, 83%, 94%, 1) 0, transparent 50%),
        radial-gradient(at 50% 0%, hsla(262, 83%, 98%, 1) 0, transparent 50%);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
    height: 100vh;
    height: 100dvh;
}

/* Typography */
h1 {
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text-primary);
    letter-spacing: -0.03em;
}

/* Layout Containers */
.main-layout {
    display: flex;
    height: 100vh;
    height: 100dvh;
    width: 100vw;
    overflow: hidden;
    background-color: var(--bg-color);
}

.sidebar {
    width: 280px;
    height: 100vh;
    background-color: #FFFFFF;
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    z-index: 1000;
    transition: var(--transition);
    flex-shrink: 0;
    box-shadow: 4px 0 15px rgba(0, 0, 0, 0.03);
}

.main-layout:not(.sidebar-open) .sidebar {
    margin-left: -280px;
}

.sidebar-header {
    padding: 24px;
    border-bottom: 1px solid rgba(139, 92, 246, 0.05);
}

.sidebar-header h1 {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.04em;
}

.btn-new-chat {
    margin: 20px 24px;
    padding: 12px 20px;
    background: var(--user-bubble);
    color: white;
    border: none;
    border-radius: 14px;
    font-weight: 700;
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.2);
}

.btn-new-chat:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(139, 92, 246, 0.3);
}

.sessions-container {
    flex: 1;
    overflow-y: auto;
    padding: 0 16px;
    margin-bottom: 20px;
}

.sessions-label {
    padding: 12px 8px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-secondary);
    opacity: 0.7;
}

.sessions-list {
    list-style: none;
}

.session-item {
    padding: 12px 14px;
    margin-bottom: 4px;
    border-radius: 12px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: all 0.2s ease;
    border: 1px solid transparent;
}

.session-item:hover {
    background-color: rgba(139, 92, 246, 0.05);
    color: var(--accent-color);
}

.session-item.active {
    background-color: var(--accent-soft);
    color: var(--accent-color);
    border-color: rgba(139, 92, 246, 0.1);
    font-weight: 600;
}

.sidebar-footer {
    padding: 24px;
    border-top: 1px solid var(--border-color);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.user-avatar {
    width: 40px;
    height: 40px;
    background-color: var(--accent-soft);
    color: var(--accent-color);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.user-details {
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.user-name {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    display: block;
}

.user-status {
    font-size: 0.75rem;
    color: #10B981;
    font-weight: 600;
}

.sidebar-logout-btn {
    width: 100%;
    padding: 10px;
    background-color: transparent;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    cursor: pointer;
    transition: var(--transition);
}

.sidebar-logout-btn:hover {
    background-color: #FEE2E2;
    border-color: #FCA5A5;
    color: #B91C1C;
}

.app-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    height: 100%;
    min-height: 0;
    background-color: #F8FAFC;
    position: relative;
    overflow: hidden;
}

.menu-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    padding: 8px;
    border-radius: 8px;
    transition: background-color 0.2s ease;
}

.menu-toggle:hover {
    background-color: rgba(139, 92, 246, 0.05);
}

/* Header Area */
.header {
    padding: 16px 20px;
    background-color: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    z-index: 10;
    flex-shrink: 0;
    position: sticky;
    top: 0;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 12px;
}

.header-logo h1 {
    font-size: 1.2rem;
    font-weight: 800;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 6px;
}

.header-logo h1::after {
    content: '';
    width: 6px;
    height: 6px;
    background-color: var(--accent-color);
    border-radius: 50%;
    margin-top: 4px;
}

/* Header styles handled by layout */
.header-menu-container {
    margin-left: auto;
    position: relative;
    display: flex;
    align-items: center;
}

.header-more-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.header-more-btn:hover {
    background-color: rgba(139, 92, 246, 0.05);
    color: var(--text-primary);
}

.header-dropdown {
    position: absolute;
    top: calc(100% + 8px);
    right: 0;
    background-color: #FFFFFF;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
    list-style: none;
    padding: 8px;
    min-width: 160px;
    z-index: 1001;
    display: none;
}

.header-dropdown.show {
    display: block;
}

.header-dropdown li {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 16px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.menu-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

.header-dropdown li:hover {
    background-color: #f3f4f6;
}

.header-dropdown li.delete-item {
    color: #DC2626;
}

.header-dropdown li.delete-item:hover {
    background-color: #FEF2F2;
}

/* Chat History Area */
.chat-window {
    flex: 1;
    overflow-y: auto;
    padding: 40px 32px;
    display: flex;
    flex-direction: column;
    gap: 28px;
    background-color: transparent;
    scrollbar-width: thin;
}

.chat-window::-webkit-scrollbar {
    width: 4px;
}

.chat-window::-webkit-scrollbar-thumb {
    background-color: rgba(139, 92, 246, 0.2);
    border-radius: 10px;
}

/* Message Bubbles */
.message {
    max-width: 80%;
    padding: 16px 22px;
    font-size: 0.98rem;
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 6px;
    line-height: 1.5;
    animation: messageSlideIn 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes messageSlideIn {
    from {
        opacity: 0;
        transform: translateY(12px) scale(0.98);
    }

    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.message-content {
    word-wrap: break-word;
    overflow-wrap: anywhere;
}

.message-content code {
    font-family: 'JetBrains Mono', 'Fira Code', monospace;
    font-size: 0.85em;
    background: rgba(139, 92, 246, 0.1);
    padding: 2px 4px;
    border-radius: 4px;
}

.message-content pre {
    margin: 12px 0;
    padding: 16px;
    background: #1e1e1e;
    color: #d4d4d4;
    border-radius: 12px;
    overflow-x: auto;
}

/* ── Assistant message content — unified typography ─────────────────── */

/* Base paragraph spacing */
.assistant-message .message-content p {
    margin: 0 0 10px 0;
    font-size: inherit;
    font-weight: 400;
    line-height: 1.65;
    color: var(--text-primary);
}

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

/* Section / semester labels (**text** at paragraph level) */
.assistant-message .message-content .msg-bold {
    font-weight: 600;
    font-style: normal;
    color: var(--text-primary);
}

/* Section heading wrapper (# / ## / ###) */
.assistant-message .message-content .msg-section-label {
    display: block;
    font-weight: 700;
    font-size: inherit;
    color: var(--text-primary);
    margin-top: 14px;
    margin-bottom: 2px;
}

/* Muted spans (*italic* replaced) — same weight, no italic */
.assistant-message .message-content .msg-muted {
    font-weight: 400;
    font-style: normal;
    opacity: 0.8;
    color: var(--text-primary);
}

/* Suppress double line breaks */
.assistant-message .message-content br+br {
    display: none;
}

/* ── Lists — shared base ──────────────────────────────────────────────── */
.assistant-message .message-content .message-list {
    margin: 4px 0 12px 0;
    padding-left: 24px;
    font-size: inherit;
    font-weight: 400;
    line-height: 1.65;
    color: var(--text-primary);
}

.assistant-message .message-content .message-list li {
    margin-bottom: 5px;
    font-weight: 400;
}

/* Override any bold/muted spans INSIDE list items to inherit weight */
.assistant-message .message-content .message-list li .msg-bold,
.assistant-message .message-content .message-list li .msg-muted,
.assistant-message .message-content .message-list li strong,
.assistant-message .message-content .message-list li em {
    font-weight: 400;
    font-style: normal;
    opacity: 1;
}

/* Accent-coloured markers for both list types */
.assistant-message .message-content .message-list li::marker {
    color: var(--accent-color);
    font-weight: 600;
}

/* Bullet list */
.assistant-message .message-content .message-list:not(.message-ol) {
    list-style-type: disc;
}

/* Ordered / numbered list */
.assistant-message .message-content .message-ol {
    list-style-type: decimal;
}

/* ── Horizontal rule ─────────────────────────────────────────────────── */
.assistant-message .message-content .msg-hr {
    border: none;
    border-top: 1px solid var(--border-color, #e5e7eb);
    margin: 12px 0;
}

/* ── Blockquote (> text) ─────────────────────────────────────────────── */
.assistant-message .message-content .msg-blockquote {
    border-left: 3px solid var(--accent-color);
    padding: 4px 12px;
    margin: 8px 0;
    color: var(--text-muted, #6b7280);
    font-style: italic;
}

/* ── Markdown tables ─────────────────────────────────────────────────── */
.assistant-message .message-content .msg-table-wrapper {
    overflow-x: auto;
    margin: 12px 0;
    border-radius: 8px;
    border: 1px solid rgba(139, 92, 246, 0.2);
}

.assistant-message .message-content .msg-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.88em;
    min-width: 360px;
}

.assistant-message .message-content .msg-table thead {
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.12), rgba(168, 85, 247, 0.08));
}

.assistant-message .message-content .msg-table th {
    padding: 9px 14px;
    text-align: left;
    font-weight: 600;
    font-size: 0.85em;
    color: var(--accent-color, #7c3aed);
    border-bottom: 2px solid rgba(139, 92, 246, 0.25);
    white-space: nowrap;
}

.assistant-message .message-content .msg-table td {
    padding: 8px 14px;
    border-bottom: 1px solid rgba(139, 92, 246, 0.1);
    vertical-align: top;
    line-height: 1.45;
}

.assistant-message .message-content .msg-table tbody tr:last-child td {
    border-bottom: none;
}

.assistant-message .message-content .msg-table tbody tr:nth-child(even) {
    background: rgba(139, 92, 246, 0.03);
}

.assistant-message .message-content .msg-table tbody tr:hover {
    background: rgba(139, 92, 246, 0.06);
}

/* Dark mode table overrides */
[data-theme="dark"] .assistant-message .message-content .msg-table-wrapper {
    border-color: rgba(167, 139, 250, 0.25);
}

[data-theme="dark"] .assistant-message .message-content .msg-table thead {
    background: linear-gradient(135deg, rgba(167, 139, 250, 0.15), rgba(196, 132, 252, 0.1));
}

[data-theme="dark"] .assistant-message .message-content .msg-table th {
    color: #c4b5fd;
    border-bottom-color: rgba(167, 139, 250, 0.3);
}

[data-theme="dark"] .assistant-message .message-content .msg-table td {
    border-bottom-color: rgba(167, 139, 250, 0.12);
}

[data-theme="dark"] .assistant-message .message-content .msg-table tbody tr:nth-child(even) {
    background: rgba(167, 139, 250, 0.05);
}

[data-theme="dark"] .assistant-message .message-content .msg-table tbody tr:hover {
    background: rgba(167, 139, 250, 0.1);
}

.assistant-message {
    align-self: flex-start;
    background-color: #FFFFFF;
    color: var(--assistant-text);
    border-radius: 4px 20px 20px 20px;
    border: 1px solid rgba(233, 228, 237, 0.8);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.02);
}

.user-message {
    align-self: flex-end;
    background: var(--user-bubble);
    color: var(--user-text);
    border-radius: 20px 20px 4px 20px;
    box-shadow: var(--shadow-bubble);
    font-weight: 500;
}

.welcome-message {
    align-self: center;
    width: 100%;
    max-width: 580px;
    margin: 60px auto;
    background-color: rgba(255, 255, 255, 0.5);
    border: 1px solid rgba(139, 92, 246, 0.1);
    border-radius: 24px;
    padding: 32px;
    text-align: center;
    color: var(--text-secondary);
    backdrop-filter: blur(4px);
}

.welcome-text {
    margin-bottom: 12px;
    font-weight: 500;
}

/* Message Links */
.message-link {
    color: inherit;
    text-decoration: underline;
    text-underline-offset: 3px;
    opacity: 0.9;
    font-weight: 600;
}

.message-link:hover {
    opacity: 1;
}

/* Input Bar Area */
.input-container {
    padding: 28px 32px 36px;
    background-color: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--border-color);
    flex-shrink: 0;
    position: sticky;
    bottom: 0;
}

.input-wrapper {
    max-width: 800px;
    margin: 0 auto;
    background-color: #FFFFFF;
    border: 1px solid var(--border-color);
    border-radius: 20px;
    display: flex;
    align-items: center;
    padding: 6px 10px 6px 24px;
    transition: var(--transition);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.02);
}

.input-wrapper:focus-within {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 4px rgba(139, 92, 246, 0.15), 0 10px 25px -10px rgba(139, 92, 246, 0.2);
}

.input-field {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    padding: 14px 0;
    font-size: 1rem;
    color: var(--text-primary);
    font-weight: 500;
}

.input-field::placeholder {
    color: #94A3B8;
    font-weight: 400;
}

.send-btn {
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: 14px;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
}

.send-btn:disabled {
    background-color: #E2E8F0;
    color: #94A3B8;
    cursor: not-allowed;
    opacity: 0.7;
}

.send-btn:hover:not(:disabled) {
    transform: scale(1.05) translateY(-2px);
    box-shadow: 0 8px 16px rgba(139, 92, 246, 0.3);
}

.send-btn:active:not(:disabled) {
    transform: scale(0.95);
}

/* Thinking Indicator */
#thinking-indicator {
    padding: 12px 24px;
    background-color: #FFFFFF;
    border-radius: 4px 16px 16px 16px;
    font-style: italic;
    font-size: 0.85rem;
    color: var(--accent-color);
    font-weight: 600;
    width: fit-content;
    border: 1px solid rgba(139, 92, 246, 0.1);
    animation: fadeIn 0.3s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

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

/* Mobile Responsiveness */
@media (max-width: 992px) {
    .main-layout.sidebar-open {
        overflow: hidden;
    }

    .sidebar {
        position: fixed;
        left: -280px;
        top: 0;
        bottom: 0;
        margin-left: 0 !important;
        z-index: 2000;
        height: 100% !important;
        width: 280px;
    }

    .main-layout.sidebar-open .sidebar {
        left: 0;
        box-shadow: 10px 0 50px rgba(0, 0, 0, 0.2);
    }
    
    .sidebar-overlay {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(31, 22, 53, 0.4);
        backdrop-filter: blur(4px);
        z-index: 1001;
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
    }
    
    .main-layout.sidebar-open .sidebar-overlay {
        opacity: 1;
        visibility: visible;
    }

    .app-container {
        width: 100% !important;
        flex: 1;
        height: 100%;
        min-height: 0;
    }
}

@media (max-width: 640px) {
    .header {
        padding: 12px 16px;
    }
    
    .header-logo h1 {
        font-size: 1.1rem;
    }

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

    .message {
        max-width: 88%;
        padding: 12px 14px;
        font-size: 0.9rem;
        margin-bottom: 12px;
    }
    
    .assistant-message {
        margin-right: 12px;
    }
    
    .user-message {
        margin-left: 12px;
    }

    .welcome-message {
        margin: 20px auto;
        padding: 24px 16px;
        max-width: 95%;
        border-radius: 20px;
    }
    
    .welcome-text {
        font-size: 0.9rem;
    }

    .input-container {
        padding: 8px 12px max(20px, env(safe-area-inset-bottom)) 12px;
    }
    
    .input-wrapper {
        padding: 6px 6px 6px 16px;
        gap: 8px;
        border-radius: 12px;
    }
    
    .input-field {
        font-size: 0.85rem;
    }
    
    .send-btn {
        width: 36px;
        height: 36px;
    }
    
    .btn-new-chat {
        margin: 12px 16px;
        padding: 10px;
        font-size: 0.85rem;
    }
    
    .sidebar-header {
        padding: 16px;
    }
    
    .sidebar-header h1 {
        font-size: 1.2rem;
    }
    
    .sidebar-footer {
        padding: 16px;
    }
    
    .user-info {
        gap: 8px;
        margin-bottom: 12px;
    }
    
    .user-avatar {
        width: 32px;
        height: 32px;
    }
}

@media (max-width: 380px) {
    .message {
        max-width: 92%;
    }
    
    .header-logo h1 {
        font-size: 1rem;
    }
}

/* Custom Modal System */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(31, 22, 53, 0.4);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.modal-overlay.show {
    opacity: 1;
    visibility: visible;
}

.modal-container {
    background-color: #FFFFFF;
    width: 90%;
    max-width: 420px;
    border-radius: 24px;
    padding: 32px;
    box-shadow: 0 20px 50px rgba(139, 92, 246, 0.15);
    transform: translateY(20px) scale(0.95);
    transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
    border: 1px solid rgba(139, 92, 246, 0.1);
}

.modal-overlay.show .modal-container {
    transform: translateY(0) scale(1);
}

.modal-header {
    margin-bottom: 16px;
}

.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.modal-body {
    margin-bottom: 28px;
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
}

.modal-input {
    width: 100%;
    padding: 12px 16px;
    margin-top: 16px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    font-size: 0.95rem;
    outline: none;
    transition: var(--transition);
}

.modal-input:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 4px rgba(139, 92, 246, 0.1);
}

.modal-footer {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
}

.modal-btn {
    padding: 10px 20px;
    border-radius: 12px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

.modal-btn-secondary {
    background-color: var(--accent-soft);
    color: var(--accent-color);
}

.modal-btn-secondary:hover {
    background-color: #EDE9FE;
}

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

.modal-btn-primary:hover {
    box-shadow: 0 4px 12px rgba(139, 92, 246, 0.3);
    transform: translateY(-1px);
}

.modal-btn-danger {
    background-color: #FEE2E2;
    color: #DC2626;
}

.modal-btn-danger:hover {
    background-color: #FECACA;
}

/* Custom Toast System */
.toast-container {
    position: fixed;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background-color: var(--text-primary);
    color: white;
    padding: 12px 24px;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 10px;
    z-index: 3000;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    opacity: 0;
}

.toast-container.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast-icon {
    color: #34D399;
    /* Green for success */
}

[data-theme="dark"] .toast-container {
    background-color: #1E1830 !important;
    color: #EDE9FF !important;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5) !important;
}

/* ============================================
   DARK MODE THEME
   ============================================ */

[data-theme="dark"] {
    --bg-color: #0F0D1A;
    --surface-color: #1A1625;
    --text-primary: #EDE9FF;
    --text-secondary: #9B8FB0;
    --accent-color: #A78BFA;
    --accent-soft: #2D2545;
    --border-color: #2E2540;
    --input-bg: #1E1830;
    --assistant-bubble: #1E1830;
    --assistant-text: #EDE9FF;
    --shadow-soft: 0 4px 6px -1px rgba(0, 0, 0, 0.35), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
    --shadow-premium: 0 10px 25px -5px rgba(167, 139, 250, 0.15), 0 8px 10px -6px rgba(167, 139, 250, 0.08);
    --shadow-bubble: 0 4px 15px rgba(167, 139, 250, 0.2);
}

[data-theme="dark"] body {
    background-image:
        radial-gradient(at 0% 0%, hsla(262, 50%, 8%, 1) 0, transparent 50%),
        radial-gradient(at 50% 0%, hsla(262, 30%, 6%, 1) 0, transparent 50%);
}

[data-theme="dark"] .sidebar {
    background-color: var(--surface-color);
    box-shadow: 4px 0 15px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .app-container {
    background-color: #13101F;
}

[data-theme="dark"] .header {
    background-color: rgba(26, 22, 37, 0.85);
}

[data-theme="dark"] .header-dropdown {
    background-color: #1E1830;
    border-color: var(--border-color);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5);
}

[data-theme="dark"] .header-dropdown li:hover {
    background-color: rgba(167, 139, 250, 0.08);
}

[data-theme="dark"] .assistant-message {
    background-color: #1E1830;
    border-color: rgba(167, 139, 250, 0.08);
}

[data-theme="dark"] .welcome-message {
    background-color: rgba(30, 24, 48, 0.7);
    border-color: rgba(167, 139, 250, 0.1);
}

[data-theme="dark"] .input-container {
    background-color: rgba(26, 22, 37, 0.9);
}

[data-theme="dark"] .input-wrapper {
    background-color: #1E1830;
}

[data-theme="dark"] .send-btn:disabled {
    background-color: #2E2540;
    color: #6B5F80;
}

[data-theme="dark"] #thinking-indicator {
    background-color: #1E1830;
}

[data-theme="dark"] .modal-container {
    background-color: #1A1625;
    border-color: rgba(167, 139, 250, 0.12);
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.6);
}

[data-theme="dark"] .modal-input {
    background-color: #1E1830;
    color: var(--text-primary);
    border-color: var(--border-color);
}

[data-theme="dark"] .modal-btn-secondary {
    background-color: #2D2545;
    color: var(--accent-color);
}

[data-theme="dark"] .modal-btn-secondary:hover {
    background-color: #3A2F5A;
}

[data-theme="dark"] .modal-btn-danger {
    background-color: rgba(220, 38, 38, 0.15);
    color: #FCA5A5;
}

[data-theme="dark"] .modal-btn-danger:hover {
    background-color: rgba(220, 38, 38, 0.25);
}

[data-theme="dark"] .sidebar-logout-btn:hover {
    background-color: rgba(220, 38, 38, 0.12);
    border-color: rgba(252, 165, 165, 0.25);
    color: #FCA5A5;
}

[data-theme="dark"] .message-content code {
    background: rgba(167, 139, 250, 0.15);
}

/* Dark mode theme toggle button (header) */
.header-theme-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    flex-shrink: 0;
}

.header-theme-btn:hover {
    background-color: rgba(139, 92, 246, 0.08);
    color: var(--accent-color);
}