@media (max-width: 767px) {
        :root {
          --topbar-height: 60px;
          --composer-height: 148px;
        }

        html,
        body {
          width: 100%;
          max-width: 100%;
          height: 100%;
          overflow: hidden;
        }

        .app-shell,
        .screen,
        .main-screen,
        .main-shell,
        .workspace,
        .content,
        .chat-view {
          width: 100%;
          max-width: 100%;
          min-width: 0;
        }

        .main-shell {
          display: block;
        }

        .sidebar {
          position: fixed;
          top: 0;
          right: 0;
          bottom: 0;
          width: min(86vw, var(--sidebar-width));
          transform: translateX(105%);
          transition: transform var(--transition);
        }

        body.sidebar-open .sidebar {
          transform: translateX(0);
        }

        body.sidebar-open .sidebar-backdrop {
          display: block;
        }

        .sidebar-dismiss-btn {
          position: fixed;
          z-index: 31;
          top: calc(var(--space-5) + 24px);
          right: calc(min(86vw, var(--sidebar-width)) + var(--space-2));
          transform: translateY(-50%);
          width: 34px;
          height: 34px;
          border-radius: 50%;
          border: 1px solid var(--border);
          background: var(--surface-raised, var(--surface));
          color: var(--text);
          font-size: 1rem;
          line-height: 1;
          cursor: pointer;
          box-shadow: 0 2px 8px rgba(0,0,0,0.25);
        }

        body.sidebar-open .sidebar-dismiss-btn {
          display: grid;
          place-items: center;
        }

        .mobile-menu-button {
          display: grid;
          place-items: center;
        }

        .welcome-view {
          padding: var(--space-6) var(--space-4);
        }

        .welcome-logo {
          width: 88px;
          height: 88px;
          border-radius: 26px;
        }

        .suggestions {
          justify-content: flex-start;
        }

        .suggestion-chip {
          width: 100%;
          white-space: normal;
        }

        .messages {
          flex: 1 1 auto;
          height: auto;
          min-height: 0;
          overflow-y: auto;
          padding: var(--space-5) var(--space-3) var(--space-5);
          padding-bottom: var(--space-5);
        }

        .message,
        .message.user {
          grid-template-columns: 42px minmax(0, 1fr);
          gap: var(--space-3);
        }

        .message.user .avatar {
          grid-column: 1;
        }

        .message.user .bubble-wrap {
          grid-column: 2;
          grid-row: 1;
          justify-items: stretch;
        }

        .avatar {
          width: 42px;
          height: 42px;
          border-radius: 14px;
        }

        .bubble {
          max-width: 100%;
          overflow: hidden;
          padding: var(--space-4);
        }

        .composer-fixed {
          position: relative;
          right: auto;
          bottom: auto;
          left: auto;
          flex: 0 0 auto;
          width: 100%;
          max-width: 100%;
          padding: var(--space-2) var(--space-3) calc(var(--space-2) + env(safe-area-inset-bottom));
          background: rgba(7, 21, 38, 0.96);
          border-top: 1px solid var(--border);
          pointer-events: auto;
        }

        html[data-theme="light"] .composer-fixed {
          background: rgba(247, 251, 255, 0.96);
        }

        .composer {
          grid-template-columns: minmax(0, 1fr) auto;
          width: 100%;
          max-width: 100%;
          border-radius: 22px;
          box-shadow: 0 8px 22px rgba(0, 0, 0, 0.18);
        }

        .composer-textarea {
          max-height: 132px;
        }

        .send-button {
          width: auto;
          min-width: 82px;
        }

        .source-meta-row {
          grid-template-columns: 1fr;
          gap: 0;
        }
      }

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

      /* ── Sidebar actions ── */
      .sidebar-actions {
        border: 1px solid var(--border);
        border-radius: var(--radius-card);
        padding: var(--space-2);
        gap: var(--space-2);
      }
      .sidebar-actions .ghost-button {
        padding-inline: var(--space-3);
        min-height: 36px;
        font-size: var(--text-xs);
      }
      @media (min-width: 768px) {
        .sidebar-actions.is-admin {
          display: grid;
          grid-template-columns: 1fr 1fr;
        }
      }
      .sidebar-logout {
        width: 100%;
        color: #e07a7a;
        border-color: rgba(224, 122, 122, 0.25);
        background: rgba(224, 122, 122, 0.07);
        font-size: var(--text-xs);
        min-height: 36px;
        border-radius: var(--radius-pill);
        border-width: 1px;
        border-style: solid;
        cursor: pointer;
        font-weight: 800;
        transition: background var(--transition), border-color var(--transition);
      }
      .sidebar-logout:hover {
        background: rgba(224, 122, 122, 0.16);
        border-color: rgba(224, 122, 122, 0.45);
      }
      @media (max-height: 580px) {
        .sidebar-logout {
          position: sticky;
          bottom: 0;
          background: var(--surface);
        }
      }

      /* ── Splash screen ── */
      .splash-overlay {
        position: fixed;
        inset: 0;
        z-index: 200;
        background: rgba(0, 0, 0, 0.65);
        display: grid;
        place-items: center;
        padding: var(--space-4);
        backdrop-filter: blur(4px);
      }
      .splash-overlay[hidden] { display: none; }
      .splash-modal {
        background: var(--surface);
        border: 1px solid var(--border-strong);
        border-radius: var(--radius-card);
        width: min(100%, 460px);
        max-height: min(80dvh, 580px);
        display: flex;
        flex-direction: column;
        overflow: hidden;
        box-shadow: var(--shadow-raised);
      }
      .splash-header {
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: var(--space-4) var(--space-5);
        border-bottom: 1px solid var(--border);
        flex-shrink: 0;
      }
      .splash-title {
        font-size: var(--text-lg);
        font-weight: 800;
        color: var(--text);
      }
      .splash-close {
        background: none;
        border: none;
        color: var(--muted);
        cursor: pointer;
        font-size: 1rem;
        padding: var(--space-1) var(--space-2);
        border-radius: 8px;
        line-height: 1;
        transition: color var(--transition), background var(--transition);
      }
      .splash-close:hover { color: var(--text); background: rgba(255,255,255,0.08); }
      .splash-body {
        flex: 1;
        overflow-y: auto;
        padding: var(--space-4) var(--space-5);
        display: grid;
        gap: var(--space-5);
        align-content: start;
      }
      .splash-version-block { display: grid; gap: var(--space-2); }
      .splash-version-tag {
        font-size: var(--text-xs);
        font-weight: 800;
        color: var(--teal);
        letter-spacing: 0.04em;
        padding-bottom: var(--space-1);
        border-bottom: 1px solid var(--border);
      }
      .splash-version-list {
        list-style: disc;
        padding-inline-start: 1.4em;
        display: grid;
        gap: 6px;
        color: var(--text);
        font-size: var(--text-sm);
        line-height: 1.5;
      }
      .splash-footer {
        padding: var(--space-3) var(--space-5);
        border-top: 1px solid var(--border);
        flex-shrink: 0;
        display: flex;
        justify-content: center;
      }
      .splash-footer .primary-button { min-width: 140px; }

      /* ── Onboarding spotlight tour ── */
      .onboarding-overlay {
        position: fixed;
        inset: 0;
        z-index: 299;
        background: transparent;
      }
      .onboarding-overlay[hidden] { display: none; }
      .onboarding-overlay.no-target {
        background: rgba(0, 0, 0, 0.72);
      }
      .onboarding-spotlight {
        position: fixed;
        z-index: 300;
        pointer-events: none;
        border-radius: 10px;
        outline: 2px solid var(--teal);
        outline-offset: 4px;
        box-shadow: 0 0 0 9999px rgba(0, 0, 0, 0.68);
        transition: top 0.22s ease, left 0.22s ease, width 0.22s ease, height 0.22s ease;
        animation: tourPulse 2.4s ease-in-out infinite;
      }
      .onboarding-spotlight[hidden] { display: none; }
      @keyframes tourPulse {
        0%, 100% { outline-color: var(--teal); box-shadow: 0 0 0 9999px rgba(0,0,0,0.68), 0 0 0 0 rgba(86,182,214,0.5); }
        50% { outline-color: rgba(86,182,214,0.6); box-shadow: 0 0 0 9999px rgba(0,0,0,0.68), 0 0 0 6px rgba(86,182,214,0.2); }
      }
      .onboarding-card {
        position: fixed;
        z-index: 301;
        background: var(--surface);
        border: 1px solid var(--border-strong);
        border-radius: var(--radius-card);
        width: min(90vw, 320px);
        padding: var(--space-4) var(--space-5);
        box-shadow: var(--shadow-raised), 0 8px 40px rgba(0, 0, 0, 0.5);
        display: flex;
        flex-direction: column;
        gap: var(--space-3);
      }
      .onboarding-header {
        display: flex;
        align-items: flex-start;
        gap: var(--space-3);
      }
      .onboarding-icon {
        font-size: 2rem;
        flex-shrink: 0;
        line-height: 1.2;
      }
      .onboarding-title {
        font-size: var(--text-base);
        font-weight: 800;
        color: var(--text);
        line-height: 1.3;
        flex: 1;
        padding-top: 0.3rem;
      }
      .onboarding-desc {
        font-size: var(--text-sm);
        color: var(--muted);
        line-height: 1.65;
        margin: 0;
      }
      .onboarding-progress {
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: var(--space-2);
      }
      .onboarding-dots {
        display: flex;
        gap: 5px;
        flex-wrap: wrap;
        max-width: 120px;
      }
      .onboarding-dot {
        width: 7px;
        height: 7px;
        border-radius: 50%;
        background: var(--border-strong);
        transition: background var(--transition), transform var(--transition);
        flex-shrink: 0;
      }
      .onboarding-dot.active {
        background: var(--teal);
        transform: scale(1.3);
      }
      .onboarding-actions {
        display: flex;
        align-items: center;
        gap: var(--space-2);
        flex-shrink: 0;
      }
      .onboarding-actions .primary-button {
        min-width: 80px;
        font-size: var(--text-sm);
        padding: var(--space-1) var(--space-3);
      }
      .onboarding-skip {
        font-size: var(--text-sm);
        color: var(--muted);
        padding: var(--space-1) var(--space-2);
      }
      @media (max-width: 400px) {
        .onboarding-card {
          width: calc(100vw - 20px);
          padding: var(--space-3) var(--space-4);
        }
      }

      /* ── FAQ sidebar icon button ── */
      .faq-icon-button {
        margin-inline-start: auto;
        flex-shrink: 0;
        width: clamp(28px, 7vw, 32px);
        height: clamp(28px, 7vw, 32px);
        min-height: unset;
        border: 1px solid var(--border-strong);
        border-radius: 50%;
        background: var(--surface-raised);
        color: var(--text);
        font-size: clamp(0.75rem, 2vw, var(--text-sm));
        font-weight: 800;
        display: grid;
        place-items: center;
        cursor: pointer;
        transition: background var(--transition), color var(--transition), border-color var(--transition), box-shadow var(--transition);
      }
      .faq-icon-button:hover {
        background: var(--surface-dynamic);
        color: var(--gold);
        border-color: var(--gold-dark);
        box-shadow: 0 0 8px rgba(86, 182, 214, 0.2);
      }

      /* ── FAQ modal ── */
      .faq-modal {
        background: var(--surface);
        border: 1px solid var(--border-strong);
        border-radius: var(--radius-card);
        width: min(100%, 580px);
        max-height: min(88dvh, 640px);
        display: flex;
        flex-direction: column;
        overflow: hidden;
        box-shadow: var(--shadow-raised);
        outline: none;
      }
      .faq-categories {
        display: flex;
        gap: var(--space-3);
        padding: var(--space-4) var(--space-5);
        border-bottom: 1px solid var(--border-strong);
        overflow-x: auto;
        flex-shrink: 0;
        scrollbar-width: none;
        background: var(--surface);
      }
      .faq-categories::-webkit-scrollbar { display: none; }
      .faq-cat-tab {
        flex-shrink: 0;
        min-height: 36px;
        border: 1px solid var(--border-strong);
        border-radius: var(--radius-pill);
        background: var(--surface-dynamic);
        color: var(--muted);
        font-size: var(--text-xs);
        font-weight: 800;
        padding: var(--space-2) var(--space-5);
        cursor: pointer;
        transition: background var(--transition), color var(--transition), border-color var(--transition), box-shadow var(--transition);
        white-space: nowrap;
      }
      .faq-cat-tab:hover {
        background: var(--surface-raised);
        color: var(--text);
        border-color: var(--teal);
      }
      .faq-cat-tab.active {
        background: var(--teal);
        border-color: var(--teal);
        color: #fff;
        box-shadow: 0 0 12px rgba(86, 182, 214, 0.3);
      }
      .faq-body {
        flex: 1;
        min-height: 0;
        overflow-y: auto;
        padding: var(--space-4) var(--space-5);
        display: flex;
        flex-direction: column;
        gap: var(--space-3);
        padding-bottom: var(--space-6);
      }
      .faq-item {
        border: 1px solid var(--border);
        border-radius: 12px;
        overflow: visible;
        background: var(--surface-raised);
        flex-shrink: 0;
      }
      .faq-question {
        width: 100%;
        min-height: 48px;
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: var(--space-3);
        padding: var(--space-3) var(--space-4);
        background: transparent;
        color: var(--text);
        font-size: var(--text-sm);
        font-weight: 700;
        text-align: right;
        cursor: pointer;
        border: none;
        border-radius: 12px;
        transition: background var(--transition);
      }
      .faq-question[aria-expanded="true"] { border-radius: 12px 12px 0 0; }
      .faq-question:hover { background: rgba(255,255,255,0.05); }
      .faq-chevron {
        color: var(--faint);
        font-size: 1.1rem;
        line-height: 1;
        transition: transform var(--transition);
        flex-shrink: 0;
      }
      .faq-answer {
        padding: var(--space-4);
        color: var(--text);
        font-size: var(--text-sm);
        line-height: 1.85;
        border-top: 1px solid var(--border);
        direction: rtl;
      }

      /* ── Mobile topbar overrides ── */
      @media (max-width: 767px) {
        .topbar {
          display: grid;
          grid-template-columns: auto 1fr auto;
          align-items: center;
          gap: var(--space-2);
          padding-inline: var(--space-3);
          min-height: var(--topbar-height);
          justify-content: unset;
        }
        .mobile-menu-button { grid-column: 1; }
        .mode-pill { grid-column: 2; justify-self: center; }
        .topbar-title {
          display: block;
          grid-column: 2;
          text-align: center;
          font-size: 11px;
          line-height: 1.35;
          color: var(--muted);
          font-weight: 700;
          padding: 0 var(--space-1);
        }
        .topbar-actions {
          order: unset;
          grid-column: 3;
          gap: var(--space-1);
        }
        #serverStatus { display: none; }
        .theme-toggle,
        .changelog-toggle {
          width: 30px;
          min-height: 30px;
          border-radius: 10px;
          font-size: 13px;
        }
      }