/* ================================================================
   CSS VARIABLES & RESET
   ================================================================ */
:root {
    /* Light theme (default) */
    --bg-primary: #f0f0f8;
    --bg-secondary: #ffffff;
    --bg-sidebar: #e8e8f0;
    --bg-input: #ffffff;
    --bg-hover: rgba(155, 89, 214, 0.10);
    --text-primary: #1a1a2e;
    --text-secondary: #3d3d5c;
    --text-muted: #6c6c8a;
    --border-color: #d0d0dd;
    --shadow-color: rgba(0, 0, 0, 0.08);
    --shadow-strong: rgba(0, 0, 0, 0.15);

    /* Accent colors */
    --accent-purple: #9b59d6;
    --accent-purple-dark: #7d3c98;
    --accent-blue: #2e86de;
    --accent-green: #1dd1a1;
    --accent-red: #e74c3c;

    /* Glow */
    --glow-purple: rgba(155, 89, 214, 0.35);
    --glow-blue: rgba(46, 134, 222, 0.25);
    --glow-green: rgba(29, 209, 161, 0.25);

    /* Message bubbles */
    --bubble-user: var(--accent-purple);
    --bubble-user-text: #ffffff;
    --bubble-ai: var(--bg-secondary);
    --bubble-ai-text: var(--text-primary);
    --bubble-ai-border: var(--border-color);

    /* Font */
    --font-base: 16px;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;

    /* Transitions */
    --transition-speed: 0.25s;
}

/* Dark theme */
[data-theme="dark"] {
    --bg-primary: #0a0a18;
    --bg-secondary: #14142a;
    --bg-sidebar: #0d0d1f;
    --bg-input: #1a1a30;
    --bg-hover: rgba(155, 89, 214, 0.18);
    --text-primary: #e4e4ff;
    --text-secondary: #b8b8d8;
    --text-muted: #8080aa;
    --border-color: #2a2a48;
    --shadow-color: rgba(0, 0, 0, 0.40);
    --shadow-strong: rgba(0, 0, 0, 0.60);
    --bubble-ai: #1a1a30;
    --bubble-ai-text: #e4e4ff;
    --bubble-ai-border: #2a2a48;
}

/* Reset & base */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: var(--font-base);
}

body {
    font-family: var(--font-family);
    background: var(--bg-primary);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    transition: background var(--transition-speed), color var(--transition-speed);
}

button {
    cursor: pointer;
    font-family: inherit;
    font-size: inherit;
    border: none;
    background: none;
    color: inherit;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: var(--accent-purple);
    border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--accent-purple-dark);
}

/* ================================================================
   NEON TEXT
   ================================================================ */
.neon-purple {
    color: var(--accent-purple);
    text-shadow: 0 0 12px var(--glow-purple), 0 0 30px var(--glow-purple);
}
.neon-blue {
    color: var(--accent-blue);
    text-shadow: 0 0 10px var(--glow-blue), 0 0 25px var(--glow-blue);
}
.neon-green {
    color: var(--accent-green);
    text-shadow: 0 0 10px var(--glow-green), 0 0 25px var(--glow-green);
}

/* ================================================================
   MODAL
   ================================================================ */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.55);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10000;
    animation: fadeIn 0.2s ease;
}

.modal-box {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 28px 32px;
    max-width: 420px;
    width: 90%;
    box-shadow: 0 20px 60px var(--shadow-strong);
    animation: slideUp 0.25s ease;
}

.modal-box h3 {
    font-size: 1.2rem;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.modal-box p {
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.5;
}

.modal-buttons {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
}

.modal-buttons button {
    padding: 10px 22px;
    border-radius: 8px;
    font-weight: 600;
    transition: transform 0.15s, box-shadow 0.15s;
}
.modal-buttons button:active {
    transform: scale(0.96);
}

.btn-secondary {
    background: var(--bg-primary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}
.btn-secondary:hover {
    background: var(--bg-hover);
}

.btn-danger {
    background: var(--accent-red);
    color: #fff;
}
.btn-danger:hover {
    box-shadow: 0 0 20px rgba(231, 76, 60, 0.4);
}

/* ================================================================
   SETTINGS MODAL (popup style)
   ================================================================ */
.settings-modal-box {
    max-width: 480px;
    padding: 24px 28px;
}

.settings-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 18px;
}
.settings-header h3 {
    font-size: 1.1rem;
    color: var(--text-primary);
}
.settings-header h3 i {
    color: var(--accent-purple);
    margin-right: 8px;
}
.settings-close-btn {
    width: 32px;
    height: 32px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-size: 1.2rem;
    transition: background 0.15s;
}
.settings-close-btn:hover {
    background: var(--bg-hover);
}

.settings-body {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.setting-row {
    display: flex;
    flex-direction: column;
    gap: 4px;
}
.setting-row label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
}
.setting-row select,
.setting-row input[type="range"] {
    padding: 8px 12px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background: var(--bg-input);
    color: var(--text-primary);
    font-size: 0.9rem;
    transition: border-color 0.15s;
}
.setting-row select:focus,
.setting-row input[type="range"]:focus {
    outline: none;
    border-color: var(--accent-purple);
}
.setting-row input[type="range"] {
    padding: 0;
    accent-color: var(--accent-purple);
}

.danger-zone {
    margin-top: 8px;
    padding-top: 14px;
    border-top: 1px solid var(--border-color);
}

.btn-danger-full {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px;
    background: var(--accent-red);
    color: #fff;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    transition: box-shadow 0.2s;
    width: 100%;
}
.btn-danger-full:hover {
    box-shadow: 0 0 28px rgba(231, 76, 60, 0.35);
}

/* ================================================================
   TOAST
   ================================================================ */
.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 12px 24px;
    box-shadow: 0 8px 30px var(--shadow-strong);
    z-index: 9999;
    font-size: 0.95rem;
    max-width: 90%;
    text-align: center;
    animation: slideUp 0.3s ease;
}
.toast.error {
    border-color: var(--accent-red);
    color: var(--accent-red);
}
.toast.success {
    border-color: var(--accent-green);
    color: var(--accent-green);
}

/* ================================================================
   APP LAYOUT
   ================================================================ */
#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background: var(--bg-primary);
}

/* ================================================================
   NAVBAR
   ================================================================ */
.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 18px;
    height: 60px;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
    z-index: 100;
    transition: background var(--transition-speed), border-color var(--transition-speed);
}

.nav-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav-icon-btn {
    width: 40px;
    height: 40px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    transition: background 0.15s;
    color: var(--text-secondary);
}
.nav-icon-btn:hover {
    background: var(--bg-hover);
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: 0.5px;
    user-select: none;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 10px;
}

.nav-right .btn-auth {
    padding: 8px 18px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    transition: background 0.15s, transform 0.15s;
}
.nav-right .btn-auth:active {
    transform: scale(0.95);
}

.btn-login {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}
.btn-login:hover {
    background: var(--bg-hover);
}

.btn-signup {
    background: var(--accent-purple);
    color: #fff;
}
.btn-signup:hover {
    box-shadow: 0 0 24px var(--glow-purple);
}

.btn-user {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 14px 6px 10px;
    border-radius: 30px;
    background: var(--bg-hover);
    border: 1px solid var(--border-color);
    font-weight: 500;
    font-size: 0.9rem;
}
.btn-user .avatar {
    width: 30px;
    height: 30px;
    border-radius: 50%;
    background: var(--accent-purple);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.8rem;
    text-transform: uppercase;
}
.btn-user:hover {
    background: var(--bg-hover);
    border-color: var(--accent-purple);
}

.btn-signout {
    padding: 6px 14px;
    border-radius: 6px;
    font-size: 0.8rem;
    color: var(--text-muted);
    border: 1px solid transparent;
}
.btn-signout:hover {
    color: var(--accent-red);
    border-color: var(--accent-red);
}

/* ================================================================
   MAIN CONTAINER (sidebar + chat)
   ================================================================ */
.main-container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* ================================================================
   SIDEBAR
   ================================================================ */
.sidebar {
    width: 280px;
    min-width: 280px;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    transition: transform var(--transition-speed) ease, margin var(--transition-speed) ease, background var(--transition-speed), border-color var(--transition-speed);
    overflow: hidden;
    z-index: 50;
}

.sidebar-header {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 14px 16px;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.btn-new-chat {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 16px;
    background: var(--accent-purple);
    color: #fff;
    border-radius: 10px;
    font-weight: 600;
    font-size: 0.9rem;
    flex: 1;
    transition: box-shadow 0.2s, transform 0.15s;
}
.btn-new-chat:hover {
    box-shadow: 0 0 28px var(--glow-purple);
}
.btn-new-chat:active {
    transform: scale(0.97);
}
.btn-new-chat i {
    font-size: 1.1rem;
}

.sidebar-close-btn {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-size: 1.1rem;
    transition: background 0.15s;
}
.sidebar-close-btn:hover {
    background: var(--bg-hover);
}
@media (min-width: 769px) {
    .sidebar-close-btn {
        display: none;
    }
}

/* Room list */
.sidebar-rooms {
    flex: 1;
    overflow-y: auto;
    padding: 8px 10px;
}

.room-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 12px;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.15s;
    margin-bottom: 2px;
    position: relative;
    group: true;
}
.room-item:hover {
    background: var(--bg-hover);
}
.room-item.active {
    background: var(--bg-hover);
    border-left: 3px solid var(--accent-purple);
}

.room-item .room-title {
    flex: 1;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.room-item .room-actions {
    display: flex;
    gap: 4px;
    opacity: 0;
    transition: opacity 0.2s;
}
.room-item:hover .room-actions {
    opacity: 1;
}
.room-item .room-actions button {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    color: var(--text-muted);
    transition: background 0.15s, color 0.15s;
}
.room-item .room-actions button:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}
.room-item .room-actions .room-delete:hover {
    color: var(--accent-red);
}

/* Sidebar footer */
.sidebar-footer {
    padding: 12px 16px;
    border-top: 1px solid var(--border-color);
    flex-shrink: 0;
}

.sidebar-user {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 6px 0;
    font-size: 0.85rem;
    color: var(--text-secondary);
}
.sidebar-user .avatar-small {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--accent-purple);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.7rem;
    text-transform: uppercase;
}
.sidebar-user .user-email {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.sidebar-settings-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    width: 100%;
    padding: 8px 12px;
    border-radius: 8px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    transition: background 0.15s;
    margin-top: 4px;
}
.sidebar-settings-btn:hover {
    background: var(--bg-hover);
}

/* ================================================================
   CHAT AREA
   ================================================================ */
.chat-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    min-width: 0;
    transition: background var(--transition-speed);
}

.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 20px 24px 12px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

/* Empty state */
.chat-empty {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    text-align: center;
    gap: 8px;
}
.chat-empty i {
    font-size: 3rem;
    color: var(--accent-purple);
    opacity: 0.3;
}
.chat-empty h2 {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--text-secondary);
}
.chat-empty p {
    font-size: 0.95rem;
    max-width: 360px;
}

/* Messages */
.message {
    display: flex;
    gap: 12px;
    max-width: 85%;
    animation: fadeIn 0.2s ease;
}
.message.user {
    align-self: flex-end;
    flex-direction: row-reverse;
}
.message.assistant {
    align-self: flex-start;
}

.message .avatar {
    width: 34px;
    height: 34px;
    border-radius: 50%;
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.8rem;
    text-transform: uppercase;
    color: #fff;
}
.message.user .avatar {
    background: var(--accent-purple);
}
.message.assistant .avatar {
    background: var(--accent-blue);
}

.message .bubble {
    padding: 12px 16px;
    border-radius: 16px;
    font-size: 0.95rem;
    line-height: 1.6;
    word-break: break-word;
    position: relative;
    transition: background var(--transition-speed), color var(--transition-speed), border-color var(--transition-speed);
}
.message.user .bubble {
    background: var(--bubble-user);
    color: var(--bubble-user-text);
    border-bottom-right-radius: 4px;
}
.message.assistant .bubble {
    background: var(--bubble-ai);
    color: var(--bubble-ai-text);
    border: 1px solid var(--bubble-ai-border);
    border-bottom-left-radius: 4px;
}

.message .bubble .message-actions {
    display: flex;
    gap: 6px;
    margin-top: 8px;
    opacity: 0;
    transition: opacity 0.2s;
}
.message:hover .bubble .message-actions,
.message .bubble .message-actions.always-show {
    opacity: 1;
}
.message .bubble .message-actions button {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    transition: background 0.15s, color 0.15s;
}
.message .bubble .message-actions button:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}
.message.user .bubble .message-actions button {
    color: rgba(255, 255, 255, 0.6);
}
.message.user .bubble .message-actions button:hover {
    background: rgba(255, 255, 255, 0.15);
    color: #fff;
}

/* Typing cursor */
.typing-cursor::after {
    content: '|';
    animation: blink 0.9s step-end infinite;
    color: var(--accent-purple);
}
@keyframes blink {
    0%,
    100% {
        opacity: 1;
    }
    50% {
        opacity: 0;
    }
}

/* Markdown in assistant messages */
.message.assistant .bubble pre {
    margin: 8px 0;
    border-radius: 8px;
    overflow: auto;
    background: var(--bg-primary);
    padding: 12px;
    position: relative;
}
.message.assistant .bubble pre code {
    font-size: 0.85rem;
    font-family: 'JetBrains Mono', 'Fira Code', monospace;
}
.message.assistant .bubble code:not(pre code) {
    background: var(--bg-primary);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.85rem;
}
.message.assistant .bubble .code-copy-btn {
    position: absolute;
    top: 6px;
    right: 6px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 4px 10px;
    font-size: 0.7rem;
    color: var(--text-muted);
    transition: opacity 0.2s;
    opacity: 0;
}
.message.assistant .bubble pre:hover .code-copy-btn {
    opacity: 1;
}
.message.assistant .bubble .code-copy-btn:hover {
    color: var(--text-primary);
}

/* ================================================================
   INPUT AREA
   ================================================================ */
.input-area {
    padding: 12px 20px 16px;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    flex-shrink: 0;
    transition: background var(--transition-speed), border-color var(--transition-speed);
}

.input-row textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background: var(--bg-input);
    color: var(--text-primary);
    font-size: 0.95rem;
    font-family: inherit;
    resize: none;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
    min-height: 48px;
    max-height: 200px;
    line-height: 1.5;
}
.input-row textarea:focus {
    border-color: var(--accent-purple);
    box-shadow: 0 0 0 3px var(--glow-purple);
}
.input-row textarea::placeholder {
    color: var(--text-muted);
}

.input-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 10px;
    gap: 8px;
    flex-wrap: wrap;
}

.toolbar-left,
.toolbar-right {
    display: flex;
    align-items: center;
    gap: 6px;
}

.model-select {
    padding: 6px 10px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background: var(--bg-input);
    color: var(--text-primary);
    font-size: 0.8rem;
    max-width: 180px;
    outline: none;
    transition: border-color 0.15s;
}
.model-select:focus {
    border-color: var(--accent-purple);
}
.model-select optgroup {
    font-weight: 700;
    color: var(--text-secondary);
}
.model-select option {
    font-weight: 400;
}

.toolbar-btn {
    padding: 6px 12px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    gap: 6px;
    color: var(--text-muted);
    font-size: 0.85rem;
    transition: background 0.15s, color 0.15s, transform 0.15s, box-shadow 0.15s;
    border: 1px solid transparent;
}
.toolbar-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}
.toolbar-btn:active {
    transform: scale(0.92);
}
.toolbar-btn.active {
    color: var(--accent-green);
    border-color: var(--accent-green);
    box-shadow: 0 0 20px var(--glow-green);
    transform: scale(1.05);
}

.web-search-btn {
    font-weight: 500;
}

.btn-send {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--accent-purple);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: box-shadow 0.2s, transform 0.15s;
    border: none;
}
.btn-send:hover {
    box-shadow: 0 0 30px var(--glow-purple);
}
.btn-send:active {
    transform: scale(0.92);
}
.btn-send:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    box-shadow: none;
}

/* File preview */
.file-preview-area {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 8px;
}
.file-preview-item {
    display: flex;
    align-items: center;
    gap: 6px;
    background: var(--bg-hover);
    padding: 4px 10px 4px 8px;
    border-radius: 6px;
    font-size: 0.8rem;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}
.file-preview-item .file-remove {
    cursor: pointer;
    color: var(--text-muted);
    font-size: 0.7rem;
}
.file-preview-item .file-remove:hover {
    color: var(--accent-red);
}

/* ================================================================
   ANIMATIONS
   ================================================================ */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}
@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ================================================================
   RESPONSIVE
   ================================================================ */

/* Tablets and small laptops */
@media (max-width: 1024px) {
    .sidebar {
        width: 260px;
        min-width: 260px;
    }
    .message {
        max-width: 90%;
    }
}

/* Mobile phones */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        top: 60px;
        left: 0;
        bottom: 0;
        width: 280px;
        min-width: 280px;
        transform: translateX(-100%);
        z-index: 60;
        border-right: none;
        box-shadow: 4px 0 30px var(--shadow-strong);
        border-radius: 0 12px 12px 0;
    }
    .sidebar.open {
        transform: translateX(0);
    }

    /* Sidebar overlay */
    .sidebar-overlay {
        position: fixed;
        inset: 0;
        top: 60px;
        background: rgba(0, 0, 0, 0.3);
        z-index: 55;
        display: none;
    }
    .sidebar-overlay.show {
        display: block;
    }

    .chat-messages {
        padding: 14px 14px 8px;
    }

    .message {
        max-width: 95%;
        gap: 8px;
    }
    .message .avatar {
        width: 28px;
        height: 28px;
        font-size: 0.65rem;
    }
    .message .bubble {
        padding: 10px 14px;
        font-size: 0.9rem;
    }

    .input-area {
        padding: 10px 12px 14px;
    }
    .input-row textarea {
        font-size: 0.9rem;
        padding: 10px 14px;
        min-height: 42px;
    }

    .model-select {
        max-width: 120px;
        font-size: 0.75rem;
        padding: 4px 8px;
    }
    .toolbar-btn {
        padding: 4px 10px;
        height: 32px;
        font-size: 0.75rem;
    }
    .btn-send {
        width: 36px;
        height: 36px;
        font-size: 0.95rem;
    }

    .settings-modal-box {
        padding: 16px 18px 24px;
        max-width: 95%;
    }

    .navbar {
        padding: 0 12px;
        height: 56px;
    }
    .logo {
        font-size: 1.2rem;
    }
    .nav-right .btn-auth {
        padding: 6px 14px;
        font-size: 0.8rem;
    }
    .btn-user {
        font-size: 0.8rem;
        padding: 4px 10px 4px 6px;
    }
    .btn-user .avatar {
        width: 26px;
        height: 26px;
        font-size: 0.7rem;
    }
}

/* Small phones */
@media (max-width: 420px) {
    .sidebar {
        width: 260px;
        min-width: 260px;
    }
    .message .bubble {
        font-size: 0.85rem;
        padding: 8px 12px;
    }
    .chat-messages {
        padding: 10px 10px 6px;
        gap: 12px;
    }
    .input-area {
        padding: 8px 8px 12px;
    }
    .input-row textarea {
        font-size: 0.85rem;
        padding: 8px 12px;
        min-height: 38px;
    }
    .model-select {
        max-width: 100px;
        font-size: 0.7rem;
    }
    .toolbar-btn {
        padding: 4px 8px;
        height: 28px;
        font-size: 0.7rem;
    }
    .btn-send {
        width: 32px;
        height: 32px;
        font-size: 0.85rem;
    }
    .settings-modal-box {
        padding: 12px 14px 20px;
    }
}

/* Show sidebar toggle on mobile, hide on desktop */
@media (min-width: 769px) {
    #sidebarToggle {
        display: none;
    }
}

/* ================================================================
   UTILITY
   ================================================================ */
.hidden {
    display: none !important;
}