/* ===== Carbon Design System Tokens ===== */
        :root {
            /* Carbon Gray 100 palette */
            --cds-background: #f4f4f4;
            --cds-layer-01: #ffffff;
            --cds-layer-02: #f4f4f4;
            --cds-layer-accent-01: #e0e0e0;
            --cds-border-subtle-00: #e0e0e0;
            --cds-border-subtle-01: #c6c6c6;
            --cds-border-strong-01: #8d8d8d;

            /* Text */
            --cds-text-primary: #161616;
            --cds-text-secondary: #525252;
            --cds-text-placeholder: #a8a8a8;
            --cds-text-on-color: #ffffff;
            --cds-text-inverse: #ffffff;

            /* Interactive */
            --cds-interactive: #0f62fe;
            --cds-interactive-hover: #0353e9;
            --cds-interactive-active: #002d9c;
            --cds-focus: #0f62fe;
            --cds-link-primary: #0f62fe;
            --cds-link-primary-hover: #0043ce;

            /* Support */
            --cds-support-success: #198038;
            --cds-support-warning: #f1c21b;
            --cds-support-error: #da1e28;
            --cds-support-info: #0043ce;

            /* Phase accent colors */
            --phase1: #198038;
            --phase2: #0f62fe;
            --phase3: #f1c21b;
            --phase4: #8a3ffc;
            --phase5: #da1e28;

            /* Spacing (Carbon 2x grid: base 8px) */
            --cds-spacing-03: 8px;
            --cds-spacing-04: 12px;
            --cds-spacing-05: 16px;
            --cds-spacing-06: 24px;
            --cds-spacing-07: 32px;
            --cds-spacing-08: 40px;
            --cds-spacing-09: 48px;
            --cds-spacing-10: 64px;
            --cds-spacing-12: 96px;

            /* Typography scale */
            --cds-heading-01: 14px;
            --cds-heading-02: 16px;
            --cds-heading-03: 20px;
            --cds-heading-04: 28px;
            --cds-heading-05: 32px;
            --cds-body-01: 14px;
            --cds-body-02: 16px;
            --cds-label-01: 12px;
            --cds-helper-text-01: 12px;
        }

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

        body {
            font-family: 'IBM Plex Sans', 'Helvetica Neue', Arial, sans-serif;
            background: var(--cds-background);
            color: var(--cds-text-primary);
            font-size: var(--cds-body-01);
            line-height: 1.43;
            -webkit-font-smoothing: antialiased;
            min-height: 100vh;
        }

        /* ===== Carbon UI Shell Header (48px) ===== */
        .cds--header {
            background: #161616;
            height: 48px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0 16px;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 8000;
            border-bottom: none;
        }

        .cds--header__name {
            font-size: 14px;
            font-weight: 600;
            color: #ffffff;
            text-decoration: none;
            padding: 0 16px;
            display: flex;
            align-items: center;
            height: 100%;
            letter-spacing: 0.1px;
        }

        .cds--header__name:hover {
            background: #353535;
        }

        .cds--header__name--prefix {
            font-weight: 400;
            margin-right: 4px;
        }

        .cds--header__nav {
            display: flex;
            align-items: center;
            height: 100%;
            list-style: none;
            margin-left: auto;
        }

        .cds--header__nav-item {
            height: 100%;
        }

        .cds--header__nav-item a {
            display: flex;
            align-items: center;
            height: 100%;
            padding: 0 16px;
            color: #c6c6c6;
            text-decoration: none;
            font-size: 14px;
            font-weight: 400;
            border: 2px solid transparent;
            transition: background 70ms, color 70ms;
            white-space: nowrap;
        }

        .cds--header__nav-item a:hover {
            background: #353535;
            color: #f4f4f4;
        }

        .cds--header__nav-item a:focus {
            border-color: var(--cds-focus);
            outline: none;
        }

        .cds--content {
            padding-top: 48px;
        }

        /* ===== Container ===== */
        .cds--grid {
            max-width: 1584px;
            margin: 0 auto;
            padding: 0 16px;
        }

        .cds--grid--narrow {
            max-width: 672px;
        }

        .container {
            max-width: 1280px;
            margin: 0 auto;
            padding: var(--cds-spacing-07) var(--cds-spacing-05);
        }

        /* ===== Carbon Tile ===== */
        .cds--tile {
            background: var(--cds-layer-01);
            padding: var(--cds-spacing-05);
            min-height: 64px;
            outline: 2px solid transparent;
            outline-offset: -2px;
            position: relative;
        }

        .cds--tile--clickable {
            cursor: pointer;
            text-decoration: none;
            color: var(--cds-text-primary);
            display: block;
            transition: background 70ms;
        }

        .cds--tile--clickable:hover {
            background: #e8e8e8;
        }

        .cds--tile--clickable:focus {
            outline: 2px solid var(--cds-focus);
        }

        /* ===== Carbon Button ===== */
        .cds--btn {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            min-height: 48px;
            padding: 13px 64px 13px 16px;
            border: none;
            font-family: 'IBM Plex Sans', sans-serif;
            font-size: 14px;
            font-weight: 400;
            letter-spacing: 0.16px;
            cursor: pointer;
            text-decoration: none;
            transition: background 70ms;
            position: relative;
            outline: none;
        }

        .cds--btn:focus {
            border: 1px solid var(--cds-focus);
            box-shadow: inset 0 0 0 1px var(--cds-focus);
        }

        .cds--btn--primary {
            background: var(--cds-interactive);
            color: var(--cds-text-on-color);
        }

        .cds--btn--primary:hover {
            background: var(--cds-interactive-hover);
        }

        .cds--btn--primary:active {
            background: var(--cds-interactive-active);
        }

        .cds--btn--secondary {
            background: #393939;
            color: var(--cds-text-on-color);
        }

        .cds--btn--secondary:hover {
            background: #4c4c4c;
        }

        .cds--btn--tertiary {
            background: transparent;
            color: var(--cds-interactive);
            border: 1px solid var(--cds-interactive);
            padding: 12px 64px 12px 16px;
        }

        .cds--btn--tertiary:hover {
            background: var(--cds-interactive-hover);
            color: var(--cds-text-on-color);
        }

        .cds--btn--ghost {
            background: transparent;
            color: var(--cds-link-primary);
            padding: 13px 16px;
        }

        .cds--btn--ghost:hover {
            background: #e8e8e8;
        }

        .cds--btn--sm {
            min-height: 32px;
            padding: 7px 64px 7px 16px;
        }

        .cds--btn--md {
            min-height: 40px;
            padding: 9px 64px 9px 16px;
        }

        .cds--btn--expressive {
            font-size: 16px;
            min-height: 48px;
        }

        /* ===== Carbon Tag ===== */
        .cds--tag {
            display: inline-flex;
            align-items: center;
            min-height: 24px;
            padding: 0 8px;
            font-size: 12px;
            font-weight: 400;
            border-radius: 24px;
            white-space: nowrap;
        }

        .cds--tag--green { background: #defbe6; color: #0e6027; }
        .cds--tag--blue { background: #d0e2ff; color: #002d9c; }
        .cds--tag--warm-gray { background: #e8e0da; color: #3c3838; }
        .cds--tag--purple { background: #e8daff; color: #6929c4; }
        .cds--tag--red { background: #ffd7d9; color: #a2191f; }
        .cds--tag--teal { background: #d9fbfb; color: #004144; }
        .cds--tag--high-contrast { background: #161616; color: #ffffff; }

        /* ===== Carbon Progress Bar ===== */
        .cds--progress-bar {
            width: 100%;
        }

        .cds--progress-bar__track {
            background: var(--cds-border-subtle-00);
            height: 8px;
            width: 100%;
        }

        .cds--progress-bar__fill {
            height: 100%;
            background: var(--cds-interactive);
            transition: width 0.4s cubic-bezier(0.2, 0, 0.38, 0.9);
        }

        .cds--progress-bar__label {
            font-size: var(--cds-label-01);
            color: var(--cds-text-secondary);
            margin-bottom: 8px;
            display: flex;
            justify-content: space-between;
        }

        /* ===== Carbon Form ===== */
        .cds--form-item {
            margin-bottom: var(--cds-spacing-06);
        }

        .cds--label {
            display: block;
            font-size: var(--cds-label-01);
            font-weight: 400;
            color: var(--cds-text-secondary);
            margin-bottom: 8px;
            letter-spacing: 0.32px;
            line-height: 1.34;
        }

        .cds--text-input {
            width: 100%;
            height: 40px;
            padding: 0 16px;
            border: none;
            border-bottom: 1px solid var(--cds-border-strong-01);
            background: var(--cds-layer-02);
            font-family: 'IBM Plex Sans', sans-serif;
            font-size: 14px;
            color: var(--cds-text-primary);
            outline: none;
            transition: border-color 70ms, box-shadow 70ms;
        }

        .cds--text-input:focus {
            outline: 2px solid var(--cds-focus);
            outline-offset: -2px;
        }

        .cds--text-input::placeholder {
            color: var(--cds-text-placeholder);
        }

        .cds--text-area {
            width: 100%;
            min-height: 160px;
            padding: 12px 16px;
            border: none;
            border-bottom: 1px solid var(--cds-border-strong-01);
            background: var(--cds-layer-02);
            font-family: 'IBM Plex Mono', monospace;
            font-size: 14px;
            color: var(--cds-text-primary);
            outline: none;
            resize: vertical;
            line-height: 1.43;
        }

        .cds--text-area:focus {
            outline: 2px solid var(--cds-focus);
            outline-offset: -2px;
        }

        /* ===== Carbon Inline Notification ===== */
        .cds--inline-notification {
            display: flex;
            align-items: flex-start;
            padding: 14px 16px;
            margin-bottom: var(--cds-spacing-05);
            min-height: 48px;
        }

        .cds--inline-notification--error {
            background: #fff1f1;
            border-left: 3px solid var(--cds-support-error);
        }

        .cds--inline-notification--success {
            background: #defbe6;
            border-left: 3px solid var(--cds-support-success);
        }

        .cds--inline-notification__text {
            font-size: 14px;
            color: var(--cds-text-primary);
        }

        /* ===== Grid layouts ===== */
        .grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--cds-spacing-05); }
        .grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--cds-spacing-05); }
        .grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--cds-spacing-05); }

        @media (max-width: 672px) {
            .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
        }

        @media (min-width: 672px) and (max-width: 1056px) {
            .grid-3 { grid-template-columns: repeat(2, 1fr); }
            .grid-4 { grid-template-columns: repeat(2, 1fr); }
        }

        /* ===== Phase tag (accent color on tile top) ===== */
        .phase-accent {
            height: 4px;
            width: 100%;
            position: absolute;
            top: 0;
            left: 0;
        }

        .cds--tile--with-accent {
            padding-top: calc(var(--cds-spacing-05) + 4px);
        }

        /* ===== Session list item ===== */
        .session-list-item {
            display: flex;
            align-items: center;
            gap: var(--cds-spacing-05);
            padding: var(--cds-spacing-05);
            background: var(--cds-layer-01);
            text-decoration: none;
            color: var(--cds-text-primary);
            border-bottom: 1px solid var(--cds-border-subtle-00);
            transition: background 70ms;
        }

        .session-list-item:hover {
            background: #e8e8e8;
        }

        .session-list-item:focus {
            outline: 2px solid var(--cds-focus);
            outline-offset: -2px;
        }

        .session-number {
            width: 32px;
            height: 32px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 600;
            font-size: 14px;
            color: var(--cds-text-on-color);
            flex-shrink: 0;
        }

        .session-info { flex: 1; min-width: 0; }
        .session-info h3 {
            font-size: 14px;
            font-weight: 600;
            line-height: 1.29;
            margin-bottom: 2px;
            letter-spacing: 0.16px;
        }
        .session-info p {
            font-size: 12px;
            color: var(--cds-text-secondary);
            line-height: 1.34;
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;
        }

        .session-status { flex-shrink: 0; font-size: 16px; }

        /* ===== Stat cards (dashboard) ===== */
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 1px;
            background: var(--cds-border-subtle-00);
            margin-bottom: var(--cds-spacing-07);
        }

        @media (max-width: 672px) {
            .stats-grid { grid-template-columns: repeat(2, 1fr); }
        }

        .stat-card {
            background: var(--cds-layer-01);
            padding: var(--cds-spacing-05);
        }

        .stat-card .stat-value {
            font-size: 36px;
            font-weight: 300;
            line-height: 1.17;
            color: var(--cds-text-primary);
            letter-spacing: 0;
        }

        .stat-card .stat-label {
            font-size: var(--cds-label-01);
            color: var(--cds-text-secondary);
            margin-top: 4px;
            letter-spacing: 0.32px;
        }

        /* ===== Badge ===== */
        .badge-card {
            display: flex;
            align-items: center;
            gap: var(--cds-spacing-04);
            padding: var(--cds-spacing-04) var(--cds-spacing-05);
            background: var(--cds-layer-01);
            border-bottom: 1px solid var(--cds-border-subtle-00);
        }

        .badge-icon {
            width: 40px;
            height: 40px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 20px;
            flex-shrink: 0;
        }

        .badge-earned { background: #defbe6; }
        .badge-locked { background: var(--cds-layer-02); filter: grayscale(1); opacity: 0.4; }

        /* ===== Knowledge / Game / Team / Exercise sections ===== */
        .knowledge-section {
            background: #defbe6;
            border-left: 3px solid var(--phase1);
            padding: var(--cds-spacing-05);
            margin: var(--cds-spacing-05) 0;
        }

        .game-section {
            background: #fcf4d6;
            border-left: 3px solid #f1c21b;
            padding: var(--cds-spacing-05);
            margin: var(--cds-spacing-05) 0;
        }

        .team-section {
            background: #e8daff;
            border-left: 3px solid var(--phase4);
            padding: var(--cds-spacing-05);
            margin: var(--cds-spacing-05) 0;
        }

        .exercise-section {
            background: #d0e2ff;
            border-left: 3px solid var(--phase2);
            padding: var(--cds-spacing-05);
            margin: var(--cds-spacing-05) 0;
        }

        /* ===== MD Editor / Preview ===== */
        .md-editor-container {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1px;
            background: var(--cds-border-subtle-00);
            min-height: 400px;
        }

        @media (max-width: 672px) {
            .md-editor-container { grid-template-columns: 1fr; }
        }

        .md-editor-container textarea {
            width: 100%;
            height: 100%;
            min-height: 400px;
            padding: var(--cds-spacing-05);
            border: none;
            background: var(--cds-layer-01);
            font-family: 'IBM Plex Mono', monospace;
            font-size: 14px;
            line-height: 1.43;
            color: var(--cds-text-primary);
            resize: vertical;
            outline: none;
        }

        .md-editor-container textarea:focus {
            outline: 2px solid var(--cds-focus);
            outline-offset: -2px;
        }

        .md-preview {
            padding: var(--cds-spacing-05);
            background: var(--cds-layer-01);
            overflow-y: auto;
            font-size: 14px;
            line-height: 1.43;
        }

        .md-preview h1 { font-size: 28px; font-weight: 300; line-height: 1.14; margin: 24px 0 8px; letter-spacing: 0; }
        .md-preview h2 { font-size: 20px; font-weight: 400; line-height: 1.4; margin: 20px 0 8px; }
        .md-preview h3 { font-size: 16px; font-weight: 600; line-height: 1.375; margin: 16px 0 8px; letter-spacing: 0.16px; }
        .md-preview h4 { font-size: 14px; font-weight: 600; line-height: 1.29; margin: 16px 0 4px; letter-spacing: 0.16px; }
        .md-preview p { margin: 8px 0; }
        .md-preview ul, .md-preview ol { padding-left: 24px; margin: 8px 0; }
        .md-preview blockquote { border-left: 3px solid var(--cds-interactive); padding: 8px 16px; margin: 8px 0; background: #edf5ff; }
        .md-preview code { background: #e8e8e8; padding: 2px 6px; font-family: 'IBM Plex Mono', monospace; font-size: 12px; }
        .md-preview pre { background: #161616; color: #f4f4f4; padding: 16px; overflow-x: auto; }
        .md-preview pre code { background: none; color: inherit; padding: 0; font-size: 14px; }
        .md-preview table { border-collapse: collapse; width: 100%; margin: 8px 0; }
        .md-preview th, .md-preview td { border-bottom: 1px solid var(--cds-border-subtle-00); padding: 14px 16px; text-align: left; font-size: 14px; }
        .md-preview th { background: #e0e0e0; font-weight: 600; font-size: 12px; letter-spacing: 0.32px; text-transform: uppercase; }
        .md-preview hr { border: none; border-top: 1px solid var(--cds-border-subtle-00); margin: 16px 0; }
        .md-preview strong { font-weight: 600; }
        .md-preview em { font-style: italic; }

        /* ===== Carbon Structured List ===== */
        .cds--structured-list {
            width: 100%;
        }

        .cds--structured-list-row {
            display: flex;
            align-items: center;
            border-bottom: 1px solid var(--cds-border-subtle-00);
        }

        .cds--structured-list-row--header {
            background: #e0e0e0;
        }

        /* ===== Breadcrumb ===== */
        .cds--breadcrumb {
            display: flex;
            align-items: center;
            gap: 8px;
            list-style: none;
            padding: 0;
            margin-bottom: var(--cds-spacing-05);
            font-size: 14px;
        }

        .cds--breadcrumb__item + .cds--breadcrumb__item::before {
            content: '/';
            margin-right: 8px;
            color: var(--cds-text-secondary);
        }

        .cds--breadcrumb a {
            color: var(--cds-link-primary);
            text-decoration: none;
        }

        .cds--breadcrumb a:hover {
            color: var(--cds-link-primary-hover);
            text-decoration: underline;
        }

        /* ===== Section heading ===== */
        .cds--heading {
            margin-bottom: var(--cds-spacing-06);
        }

        .cds--heading--04 {
            font-size: 28px;
            font-weight: 300;
            line-height: 1.14;
            letter-spacing: 0;
        }

        .cds--heading--03 {
            font-size: 20px;
            font-weight: 400;
            line-height: 1.4;
        }

        .cds--heading--02 {
            font-size: 16px;
            font-weight: 600;
            line-height: 1.375;
            letter-spacing: 0.16px;
        }

        .cds--heading--01 {
            font-size: 14px;
            font-weight: 600;
            line-height: 1.29;
            letter-spacing: 0.16px;
        }

        /* ===== Utility ===== */
        .mb-03 { margin-bottom: var(--cds-spacing-03); }
        .mb-05 { margin-bottom: var(--cds-spacing-05); }
        .mb-06 { margin-bottom: var(--cds-spacing-06); }
        .mb-07 { margin-bottom: var(--cds-spacing-07); }
        .mb-09 { margin-bottom: var(--cds-spacing-09); }
        .mt-05 { margin-top: var(--cds-spacing-05); }
        .mt-07 { margin-top: var(--cds-spacing-07); }
        .text-secondary { color: var(--cds-text-secondary); }
        .text-center { text-align: center; }

        .section-divider {
            border: none;
            border-top: 1px solid var(--cds-border-subtle-00);
            margin: var(--cds-spacing-07) 0;
        }