:root {
            --groningen-red: #DA121A;
            --groningen-blue: #0F47AF;
            --groningen-green: #078930;
            --dark-gray: #333333;
            --light-gray: #f8f9fa;
            --medium-gray: #666666;
            --heading-font: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
            --body-font: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
        }

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

        body {
            font-family: var(--body-font);
            background: var(--light-gray);
            color: var(--dark-gray);
            height: 100vh;
            display: flex;
            flex-direction: column;
        }

        /* ── Header ────────────────────────────────────── */
        .site-header {
            background: #fff;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
            padding: 0 24px;
            height: 60px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-shrink: 0;
        }

        .site-header .logo-area {
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .site-header .logo {
            display: flex;
            align-items: center;
            gap: 10px;
            text-decoration: none;
            color: inherit;
        }

        .site-header .logo span {
            font-family: var(--heading-font);
            font-weight: 700;
            font-size: 1.3rem;
            color: var(--groningen-green);
        }

        .site-header .logo-divider {
            width: 1px;
            height: 22px;
            background: #d0d0d0;
            flex-shrink: 0;
        }

        .site-header .logo-sub {
            font-family: var(--heading-font);
            font-weight: 600;
            font-size: 1rem;
            color: var(--groningen-blue);
        }

        .site-header nav {
            display: flex;
            align-items: center;
            gap: 4px;
        }

        .site-header nav a {
            color: var(--dark-gray);
            text-decoration: none;
            font-weight: 500;
            font-size: 0.9rem;
            padding: 6px 12px;
            border-radius: 6px;
            transition: background 0.15s, color 0.15s;
        }

        .site-header nav a:hover {
            background: var(--light-gray);
            color: var(--groningen-blue);
        }

        /* ── Screens ───────────────────────────────────── */
        .screen { display: none; flex: 1; }
        .screen.active { display: flex; }

        /* ── Screen: Role Selection ─────────────────────── */
        #screen-role {
            align-items: center;
            justify-content: center;
            padding: 40px 20px;
            overflow-y: auto;
        }

        .role-wrapper {
            text-align: center;
            max-width: 600px;
            width: 100%;
        }

        .role-wrapper h2 {
            font-size: 2rem;
            color: var(--dark-gray);
            margin-bottom: 8px;
        }

        .role-wrapper p {
            color: var(--medium-gray);
            margin-bottom: 40px;
            font-size: 1.05rem;
        }

        .role-cards {
            display: flex;
            gap: 24px;
            justify-content: center;
            flex-wrap: wrap;
        }

        .role-card {
            background: #fff;
            border: 2px solid #e0e0e0;
            border-radius: 12px;
            padding: 32px 28px;
            cursor: pointer;
            transition: border-color 0.2s, transform 0.15s, box-shadow 0.2s;
            width: 220px;
            text-align: center;
            user-select: none;
        }

        .role-card:hover {
            border-color: var(--groningen-blue);
            transform: translateY(-4px);
            box-shadow: 0 8px 24px rgba(15,71,175,0.15);
        }

        .role-card .role-icon { font-size: 3rem; margin-bottom: 12px; }

        .role-card h3 {
            font-size: 1.1rem;
            margin-bottom: 8px;
            color: var(--dark-gray);
        }

        .role-card p {
            font-size: 0.88rem;
            color: var(--medium-gray);
            margin: 0;
        }

        .role-card.role-controller:hover { border-color: var(--groningen-blue); }
        .role-card.role-participant:hover { border-color: var(--groningen-green); }

        /* ── Screen: Session Setup ──────────────────────── */
        #screen-setup {
            align-items: center;
            justify-content: center;
            padding: 40px 20px;
            overflow-y: auto;
        }

        .setup-box {
            background: #fff;
            border-radius: 12px;
            padding: 40px;
            max-width: 440px;
            width: 100%;
            box-shadow: 0 4px 20px rgba(0,0,0,0.08);
        }

        .setup-box h2 {
            font-size: 1.6rem;
            margin-bottom: 8px;
            color: var(--dark-gray);
        }

        .setup-box p {
            color: var(--medium-gray);
            margin-bottom: 24px;
            font-size: 0.95rem;
        }

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

        .form-group-inline {
            display: flex;
            flex-direction: row;
            align-items: center;
            gap: 10px;
        }

        .form-group-inline input[type=checkbox] {
            width: auto;
            padding: 0;
            border: none;
            cursor: pointer;
            flex-shrink: 0;
        }

        .form-group-inline label {
            display: inline;
            margin-bottom: 0;
            cursor: pointer;
        }

        .form-group label {
            display: block;
            font-weight: 600;
            margin-bottom: 6px;
            font-size: 0.9rem;
            color: var(--dark-gray);
        }

        .form-group input, .form-group select, .form-group textarea {
            width: 100%;
            padding: 10px 14px;
            border: 1.5px solid #d0d0d0;
            border-radius: 6px;
            font-size: 1rem;
            font-family: var(--body-font);
            transition: border-color 0.2s;
            background: #fff;
        }

        .form-group input:focus, .form-group select:focus, .form-group textarea:focus {
            outline: none;
            border-color: var(--groningen-blue);
        }

        .btn-primary {
            background: var(--groningen-green);
            color: #fff;
            border: none;
            padding: 12px 28px;
            border-radius: 6px;
            font-size: 1rem;
            font-family: var(--body-font);
            font-weight: 600;
            cursor: pointer;
            transition: background 0.2s;
            width: 100%;
        }

        .btn-primary:hover { background: #056e25; }
        .btn-primary:disabled { background: #aaa; cursor: not-allowed; }

        .btn-secondary {
            background: var(--groningen-blue);
            color: #fff;
            border: none;
            padding: 10px 22px;
            border-radius: 6px;
            font-size: 0.95rem;
            font-family: var(--body-font);
            font-weight: 600;
            cursor: pointer;
            transition: background 0.2s;
        }

        .btn-secondary:hover { background: #0a3a8e; }

        .btn-ghost {
            background: none;
            border: none;
            color: var(--medium-gray);
            font-size: 0.9rem;
            cursor: pointer;
            font-family: var(--body-font);
            padding: 6px 0;
            text-decoration: underline;
            text-underline-offset: 2px;
            display: inline-block;
            margin-top: 12px;
        }

        .btn-ghost:hover { color: var(--dark-gray); }

        /* ── Status Bar ─────────────────────────────────── */
        .status-bar {
            display: flex;
            align-items: center;
            gap: 8px;
            font-size: 0.85rem;
            color: var(--medium-gray);
        }

        .status-dot {
            width: 10px;
            height: 10px;
            border-radius: 50%;
            background: #aaa;
            flex-shrink: 0;
        }

        .status-dot.connecting { background: #f59e0b; animation: pulse 1.2s ease-in-out infinite; }
        .status-dot.connected { background: var(--groningen-green); }
        .status-dot.disconnected { background: var(--groningen-red); }
        .status-dot.ended { background: #9ca3af; }

        @keyframes pulse {
            0%, 100% { opacity: 1; }
            50% { opacity: 0.4; }
        }

        /* ── Screen: Controller ─────────────────────────── */
        #screen-controller {
            flex-direction: column;
            overflow: hidden;
            height: calc(100vh - 60px);
        }

        .controller-layout {
            display: flex;
            flex: 1;
            overflow: hidden;
            gap: 0;
        }

        .ctrl-main {
            flex: 1;
            display: flex;
            flex-direction: column;
            overflow: hidden;
            padding: 20px;
            gap: 12px;
            min-width: 0;
        }

        .ctrl-main h1 {
            font-size: 1.8rem;
            color: var(--dark-gray);
            flex-shrink: 0;
        }

        .ctrl-sidebar {
            width: 280px;
            flex-shrink: 0;
            background: #fff;
            border-left: 1px solid #e0e0e0;
            padding: 20px;
            display: flex;
            flex-direction: column;
            gap: 16px;
            overflow-y: auto;
        }

        @media (max-width: 768px) {
            .controller-layout { flex-direction: column; }
            .ctrl-sidebar {
                width: 100%;
                border-left: none;
                border-top: 1px solid #e0e0e0;
                flex-direction: row;
                flex-wrap: wrap;
                gap: 12px;
                padding: 16px;
            }
            .ctrl-sidebar > * { flex: 1 1 140px; }
        }

        /* PIN display */
        .pin-display {
            text-align: center;
        }

        .pin-label {
            font-size: 0.75rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 0.1em;
            color: var(--medium-gray);
            margin-bottom: 4px;
        }

        .pin-value {
            font-size: 5rem;
            font-weight: 900;
            color: var(--groningen-blue);
            letter-spacing: 0.08em;
            line-height: 1.1;
            font-family: 'Courier New', monospace;
        }

        @media (max-width: 768px) {
            .pin-value { font-size: 3rem; }
        }

        .pin-url-row {
            display: flex;
            flex-direction: column;
            gap: 6px;
            margin-top: 8px;
        }

        .url-display {
            font-size: 0.88rem;
            font-weight: 600;
            color: var(--groningen-blue);
            word-break: break-all;
            line-height: 1.45;
            padding: 4px 0;
        }

        .btn-copy-full {
            width: 100%;
            text-align: center;
        }

        .url-shortening {
            font-size: 0.75rem;
            color: var(--medium-gray);
        }

        .btn-copy {
            background: var(--groningen-blue);
            color: #fff;
            border: none;
            padding: 6px 10px;
            border-radius: 4px;
            font-size: 0.8rem;
            cursor: pointer;
            white-space: nowrap;
            font-family: var(--body-font);
        }

        .btn-copy:hover { background: #0a3a8e; }
        .btn-copy.copied { background: var(--groningen-green); }

        .qr-section { display: flex; flex-direction: column; gap: 0; }

        .qr-toggle {
            display: flex;
            align-items: center;
            justify-content: space-between;
            cursor: pointer;
            user-select: none;
            font-size: 0.75rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 0.07em;
            color: var(--medium-gray);
            padding: 4px 0;
            border: none;
            background: none;
            width: 100%;
            font-family: var(--body-font);
        }
        .qr-toggle:hover { color: var(--dark-gray); }
        .qr-toggle .qr-chevron { transition: transform 0.2s; font-style: normal; }
        .qr-toggle.collapsed .qr-chevron { transform: rotate(-90deg); }

        #qrcode {
            display: flex;
            justify-content: center;
            overflow: hidden;
            transition: max-height 0.25s ease, opacity 0.2s;
            max-height: 220px;
            opacity: 1;
        }
        #qrcode.hidden { max-height: 0; opacity: 0; pointer-events: none; }

        #qrcode canvas, #qrcode img { border-radius: 6px; }

        .participant-count {
            text-align: center;
            font-size: 0.9rem;
            color: var(--medium-gray);
        }

        .participant-count strong {
            font-size: 1.4rem;
            color: var(--dark-gray);
            display: block;
        }

        .participant-list {
            margin-top: 10px;
            display: flex;
            flex-direction: column;
            gap: 4px;
            max-height: 180px;
            overflow-y: auto;
        }

        .participant-list-item {
            display: flex;
            align-items: center;
            gap: 7px;
            font-size: 0.82rem;
            color: var(--dark-gray);
            padding: 3px 6px;
            border-radius: 4px;
            background: var(--light-gray);
            justify-content: space-between;
        }

        .participant-item-name {
            display: flex;
            align-items: center;
            gap: 6px;
            flex: 1;
            min-width: 0;
            overflow: hidden;
            text-overflow: ellipsis;
            white-space: nowrap;
        }

        .participant-item-name::before {
            content: '';
            width: 8px;
            height: 8px;
            border-radius: 50%;
            background: var(--groningen-green);
            flex-shrink: 0;
        }

        .color-picker-btn {
            width: 18px;
            height: 18px;
            border-radius: 50%;
            border: 2px solid rgba(0,0,0,0.18);
            cursor: pointer;
            padding: 0;
            flex-shrink: 0;
            transition: border-color 0.15s, transform 0.1s;
        }
        .color-picker-btn:hover { border-color: rgba(0,0,0,0.55); transform: scale(1.2); }

        .color-popover {
            position: fixed;
            z-index: 2000;
            background: #fff;
            border-radius: 8px;
            padding: 8px;
            box-shadow: 0 4px 20px rgba(0,0,0,0.22);
            display: grid;
            grid-template-columns: repeat(4, 26px);
            gap: 5px;
        }
        .color-swatch {
            width: 26px;
            height: 26px;
            border-radius: 50%;
            border: 2px solid transparent;
            cursor: pointer;
            padding: 0;
            transition: border-color 0.1s, transform 0.1s;
        }
        .color-swatch:hover, .color-swatch.selected { border-color: #333; transform: scale(1.15); }
        .color-swatch-none {
            background: #f0f0f0;
            font-size: 0.65rem;
            color: #666;
            display: flex;
            align-items: center;
            justify-content: center;
            line-height: 1;
        }

        /* ── Message Feed ───────────────────────────────── */
        .feed {
            flex: 1;
            overflow-y: auto;
            background: #fff;
            border-radius: 8px;
            border: 1px solid #e0e0e0;
            padding: 16px;
            display: flex;
            flex-direction: column;
            gap: 10px;
            min-height: 0;
        }

        .msg {
            padding: 10px 12px;
            border-radius: 6px;
            background: var(--light-gray);
            border-left: 3px solid transparent;
            flex-shrink: 0;
        }

        .msg .msg-header {
            display: flex;
            align-items: baseline;
            gap: 8px;
            margin-bottom: 4px;
        }

        .msg .msg-sender {
            font-weight: 700;
            font-size: 0.9rem;
            color: var(--groningen-blue);
        }

        .msg .msg-sender.is-host { color: var(--groningen-green); }

        .msg .msg-time {
            font-size: 0.75rem;
            color: var(--medium-gray);
        }

        .msg .msg-text {
            font-size: 1.4rem;
            line-height: 1.5;
            color: var(--dark-gray);
            word-break: break-word;
        }

        /* Controller view — larger fonts for beamer readability */
        #screen-controller .msg .msg-text {
            font-size: 1.8rem;
            line-height: 1.45;
        }

        #screen-controller .msg .msg-sender {
            font-size: 1.1rem;
        }

        #screen-controller .msg .msg-time {
            font-size: 0.9rem;
        }

        #screen-controller .snippet-code-block {
            font-size: 1.15rem;
            line-height: 1.65;
        }

        #screen-controller .snippet-sender {
            font-size: 1rem;
        }

        #screen-controller .snippet-lang-badge {
            font-size: 0.85rem;
            padding: 3px 10px;
        }

        #screen-controller .msg-system {
            font-size: 1.1rem;
        }

        /* Participant view uses smaller font */
        #screen-participant .msg .msg-text,
        #screen-join .msg .msg-text {
            font-size: 1rem;
        }

        .msg-system {
            font-style: italic;
            color: var(--medium-gray);
            font-size: 0.9rem;
            padding: 6px 12px;
            text-align: center;
            flex-shrink: 0;
        }

        /* Code snippets */
        .msg-snippet {
            background: #f6f8fa;
            border-radius: 8px;
            overflow: hidden;
            flex-shrink: 0;
            border: 1px solid #d0d7de;
        }

        .snippet-header {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 8px 12px;
            background: #eaeef2;
            border-bottom: 1px solid #d0d7de;
        }

        .snippet-meta {
            display: flex;
            align-items: baseline;
            gap: 8px;
        }

        .snippet-sender {
            font-weight: 700;
            font-size: 0.85rem;
            color: #24292f;
        }

        .snippet-time {
            font-size: 0.75rem;
            color: #57606a;
        }

        .snippet-lang-badge {
            font-size: 0.75rem;
            font-weight: 700;
            text-transform: uppercase;
            padding: 2px 8px;
            border-radius: 3px;
            background: var(--groningen-blue);
            color: #fff;
            letter-spacing: 0.05em;
        }

        .snippet-lang-badge.lang-php { background: #6366f1; }
        .snippet-lang-badge.lang-javascript { background: #d4a017; color: #1a1a1a; }
        .snippet-lang-badge.lang-python { background: #3776ab; }
        .snippet-lang-badge.lang-html { background: #e44d26; }
        .snippet-lang-badge.lang-css { background: #264de4; }
        .snippet-lang-badge.lang-plaintext { background: #6b7280; }

        .snippet-copy-btn {
            background: #fff;
            color: #57606a;
            border: 1px solid #d0d7de;
            padding: 4px 10px;
            border-radius: 4px;
            font-size: 0.78rem;
            cursor: pointer;
            font-family: var(--body-font);
            transition: background 0.15s, border-color 0.15s;
        }

        .snippet-copy-btn:hover { background: #f3f4f6; border-color: #adb5bd; color: #24292f; }
        .snippet-copy-btn.copied { background: var(--groningen-green); color: #fff; border-color: var(--groningen-green); }

        .snippet-code-block {
            margin: 0;
            overflow-x: auto;
            padding: 16px;
            font-size: 0.9rem;
            line-height: 1.6;
            font-family: 'Courier New', 'Fira Code', monospace;
        }

        .snippet-code-block code {
            display: inline;
            padding: 0;
            font-size: inherit;
            line-height: inherit;
            font-family: inherit;
        }

        /* ── Input bar ──────────────────────────────────── */
        .input-bar {
            display: flex;
            gap: 8px;
            flex-shrink: 0;
            background: #fff;
            border-radius: 8px;
            border: 1px solid #e0e0e0;
            padding: 10px;
        }

        .autoscroll-row {
            display: flex;
            align-items: center;
            gap: 6px;
            padding: 2px 4px;
            flex-shrink: 0;
        }

        .autoscroll-row label {
            font-size: 0.8rem;
            color: var(--medium-gray);
            cursor: pointer;
            user-select: none;
        }

        .autoscroll-row input[type=checkbox] {
            accent-color: var(--groningen-green);
            width: 14px;
            height: 14px;
            cursor: pointer;
        }

        .input-bar input[type=text] {
            flex: 1;
            border: none;
            outline: none;
            font-size: 1rem;
            font-family: var(--body-font);
            min-width: 0;
        }

        .btn-send {
            background: var(--groningen-green);
            color: #fff;
            border: none;
            padding: 8px 18px;
            border-radius: 5px;
            font-size: 0.95rem;
            font-family: var(--body-font);
            font-weight: 600;
            cursor: pointer;
            transition: background 0.2s;
            white-space: nowrap;
        }

        .btn-send:hover { background: #056e25; }
        .btn-send:disabled { background: #aaa; cursor: not-allowed; }

        .btn-code {
            background: #fff;
            color: var(--groningen-blue);
            border: 1.5px solid var(--groningen-blue);
            padding: 8px 14px;
            border-radius: 5px;
            font-size: 0.9rem;
            font-family: var(--body-font);
            font-weight: 600;
            cursor: pointer;
            transition: background 0.2s;
            white-space: nowrap;
        }

        .btn-code:hover { background: #eff3ff; }
        .btn-code:disabled { opacity: 0.5; cursor: not-allowed; }

        /* ── Screen: Participant ────────────────────────── */
        #screen-participant {
            flex-direction: column;
            overflow: hidden;
            height: calc(100vh - 60px);
        }

        .participant-layout {
            flex: 1;
            display: flex;
            flex-direction: column;
            overflow: hidden;
            padding: 20px;
            gap: 12px;
            max-width: 900px;
            margin: 0 auto;
            width: 100%;
        }

        .participant-layout h1 {
            font-size: 1.6rem;
            color: var(--dark-gray);
            flex-shrink: 0;
        }

        /* ── Screen: Join ────────────────────────────────── */
        #screen-join {
            align-items: center;
            justify-content: center;
            padding: 40px 20px;
            overflow-y: auto;
        }

        .join-box {
            background: #fff;
            border-radius: 12px;
            padding: 40px;
            max-width: 420px;
            width: 100%;
            box-shadow: 0 4px 20px rgba(0,0,0,0.08);
        }

        .join-box h2 {
            font-size: 1.6rem;
            margin-bottom: 8px;
        }

        .join-box p {
            color: var(--medium-gray);
            margin-bottom: 24px;
            font-size: 0.95rem;
        }

        .form-group input[type=number] {
            font-size: 1.8rem;
            font-weight: 700;
            letter-spacing: 0.3em;
            text-align: center;
            font-family: 'Courier New', monospace;
        }

        .error-msg {
            background: #fef2f2;
            border: 1px solid #fca5a5;
            color: #dc2626;
            padding: 10px 14px;
            border-radius: 6px;
            font-size: 0.9rem;
            margin-top: 12px;
            display: none;
        }

        .error-msg.visible { display: block; }

        /* ── Code Snippet Modal ─────────────────────────── */
        .modal-overlay {
            display: none;
            position: fixed;
            inset: 0;
            background: rgba(0,0,0,0.5);
            z-index: 1000;
            align-items: center;
            justify-content: center;
            padding: 20px;
        }

        .modal-overlay.open { display: flex; }

        .modal-box {
            background: #fff;
            border-radius: 12px;
            padding: 28px;
            max-width: 560px;
            width: 100%;
            box-shadow: 0 20px 60px rgba(0,0,0,0.2);
        }

        .modal-box h3 {
            font-size: 1.2rem;
            margin-bottom: 16px;
        }

        .modal-box textarea {
            font-family: 'Courier New', 'Fira Code', monospace;
            font-size: 0.9rem;
            line-height: 1.5;
            min-height: 220px;
            resize: vertical;
        }

        .modal-actions {
            display: flex;
            gap: 10px;
            justify-content: flex-end;
            margin-top: 16px;
        }

        .btn-cancel {
            background: none;
            border: 1.5px solid #d0d0d0;
            color: var(--dark-gray);
            padding: 10px 20px;
            border-radius: 6px;
            font-size: 0.95rem;
            font-family: var(--body-font);
            cursor: pointer;
            transition: border-color 0.2s;
        }

        .btn-cancel:hover { border-color: #999; }

        /* ── Session ended notice ───────────────────────── */
        .session-ended-notice {
            display: none;
            background: #fef3c7;
            border: 1px solid #f59e0b;
            color: #92400e;
            padding: 10px 16px;
            border-radius: 6px;
            font-size: 0.9rem;
            text-align: center;
            flex-shrink: 0;
        }

        .session-ended-notice.visible { display: block; }

        /* ── Controller status row ──────────────────────── */
        .ctrl-status-row {
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-shrink: 0;
        }

        .btn-fullscreen {
            background: none;
            border: 1.5px solid #d0d0d0;
            color: var(--medium-gray);
            border-radius: 6px;
            padding: 4px 10px;
            font-size: 1rem;
            cursor: pointer;
            line-height: 1;
            flex-shrink: 0;
            transition: background 0.15s, color 0.15s;
        }
        .btn-fullscreen:hover { background: var(--light-gray); color: var(--dark-gray); }

        /* ── Fullscreen mode ────────────────────────────────── */
        body.is-fullscreen .site-header { display: none; }
        body.is-fullscreen #ctrl-input-bar { display: none; }
        body.is-fullscreen #screen-controller .autoscroll-row { display: none; }
        body.is-fullscreen #screen-controller { height: 100vh; }

        /* ── Participant status row ─────────────────────── */
        .participant-status-row {
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-shrink: 0;
        }