/* ── Tab-Navigation ── */
        .tab-bar {
            display: flex;
            gap: 0.5rem;
            margin-bottom: 2rem;
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: var(--radius);
            padding: 0.5rem;
            width: 100%;
        }

        .tab-btn {
            flex: 1;
            padding: 0.75rem 1.25rem;
            border: none;
            background: transparent;
            color: var(--clr-muted);
            border-radius: 10px;
            cursor: pointer;
            font-size: 0.92rem;
            font-weight: 600;
            font-family: inherit;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            transition: var(--transition-fast);
        }

        .tab-btn:hover {
            background: var(--box-bg);
            color: var(--clr-text);
        }

        .tab-btn.active {
            background: linear-gradient(135deg, var(--clr-accent), var(--clr-accent2));
            color: var(--clr-on-accent);
            font-weight: 700;
        }

        .tab-content {
            display: none;
            width: 100%;
        }

        .tab-content.active {
            display: block;
        }

        /* ── Theorie-Karten ── */
        .theory-card {
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: var(--radius);
            padding: 1.75rem;
            margin-bottom: 1.5rem;
            box-shadow: var(--shadow-sm);
            transition: var(--transition-fast);
            width: 100%;
        }

        .theory-card:hover {
            box-shadow: var(--shadow);
            border-color: var(--clr-accent);
        }

        .theory-card h3 {
            font-size: 1.15rem;
            font-weight: 700;
            margin-bottom: 1rem;
            color: var(--clr-accent-text);
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .theory-card p {
            color: var(--clr-muted);
            font-size: 0.95rem;
            line-height: 1.7;
            margin-bottom: 0.75rem;
        }

        .theory-card p:last-child {
            margin-bottom: 0;
        }

        /* ── VN-Architektur-Diagramm ── */
        .vn-diagram {
            display: grid;
            grid-template-columns: 1fr 1fr 1fr;
            gap: 1rem;
            margin: 1.5rem 0;
        }

        .vn-block {
            background: var(--box-bg);
            border: 1px solid var(--border-color);
            border-radius: 10px;
            padding: 1rem;
            text-align: center;
        }

        .vn-block.cpu {
            grid-column: 1 / 3;
            border-color: var(--clr-accent);
            background: rgba(52, 211, 153, 0.05);
        }

        .vn-block.memory {
            border-color: var(--clr-accent2);
            background: rgba(56, 189, 248, 0.05);
        }

        .vn-block.io-row {
            grid-column: 1 / 4;
            border-color: var(--warning);
            background: rgba(251, 191, 36, 0.05);
            display: flex;
            justify-content: space-around;
            align-items: center;
            flex-wrap: wrap;
            gap: 1rem;
            padding: 1rem 2rem;
        }

        .vn-block-label {
            font-size: 0.68rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 0.08em;
            color: var(--clr-muted);
            margin-bottom: 0.4rem;
        }

        .vn-block-title {
            font-size: 1rem;
            font-weight: 700;
            margin-bottom: 0.5rem;
        }

        .vn-block.cpu .vn-block-title {
            color: var(--clr-accent-text);
        }

        .vn-block.memory .vn-block-title {
            color: var(--clr-accent2-text);
        }

        .vn-block.io-row .vn-block-title {
            color: var(--warning-text);
        }

        .cpu-inner {
            display: flex;
            gap: 0.75rem;
            margin-top: 0.75rem;
            flex-wrap: wrap;
        }

        .cpu-part {
            flex: 1;
            min-width: 120px;
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 0.75rem;
            font-size: 0.82rem;
            color: var(--clr-muted);
            text-align: left;
        }

        .cpu-part strong {
            display: block;
            color: var(--clr-accent-text);
            margin-bottom: 0.3rem;
            font-size: 0.85rem;
        }

        /* ── Tabellen ── */
        .styled-table {
            width: 100%;
            border-collapse: collapse;
            font-size: 0.88rem;
            margin-top: 1rem;
        }

        .styled-table th {
            background: rgba(52, 211, 153, 0.15);
            color: var(--clr-accent-text);
            padding: 0.7rem 1rem;
            text-align: left;
            font-weight: 700;
            border-bottom: 2px solid var(--clr-accent);
        }

        .styled-table td {
            padding: 0.65rem 1rem;
            border-bottom: 1px solid var(--border-color);
            color: var(--clr-muted);
            vertical-align: top;
        }

        .styled-table tr:last-child td {
            border-bottom: none;
        }

        .styled-table tr:hover td {
            background: var(--box-bg);
            color: var(--clr-text);
        }

        .reg-badge {
            display: inline-block;
            background: rgba(56, 189, 248, 0.15);
            color: var(--clr-accent2-text);
            padding: 2px 8px;
            border-radius: 4px;
            font-family: 'Courier New', monospace;
            font-size: 0.85rem;
            font-weight: 700;
            border: 1px solid rgba(56, 189, 248, 0.3);
        }

        .instr-group {
            background: rgba(52, 211, 153, 0.08) !important;
            color: var(--clr-accent-text) !important;
            font-weight: 700;
            font-family: 'Segoe UI', sans-serif !important;
        }

        /* ── Fetch-Decode-Execute ── */
        .cycle-steps {
            display: flex;
            gap: 0;
            margin: 1.25rem 0;
            overflow-x: auto;
            padding-bottom: 0.5rem;
        }

        .cycle-step {
            flex: 1;
            min-width: 130px;
            text-align: center;
            position: relative;
        }

        .cycle-step-num {
            width: 38px;
            height: 38px;
            background: linear-gradient(135deg, var(--clr-accent), var(--clr-accent2));
            color: var(--clr-on-accent);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 800;
            margin: 0 auto 0.6rem;
            font-size: 0.95rem;
            z-index: 1;
            position: relative;
        }

        .cycle-step:not(:last-child)::after {
            content: '';
            position: absolute;
            top: 19px;
            left: 50%;
            width: 100%;
            height: 2px;
            background: linear-gradient(90deg, var(--clr-accent), var(--clr-accent2));
            z-index: 0;
            opacity: 0.4;
        }

        .cycle-step-title {
            font-weight: 700;
            font-size: 0.82rem;
            color: var(--clr-accent-text);
        }

        .cycle-step-desc {
            font-size: 0.76rem;
            color: var(--clr-muted);
            margin-top: 0.3rem;
            padding: 0 0.5rem;
            line-height: 1.4;
        }

        /* ── Code-Block ── */
        .code-block {
            background: rgba(0, 0, 0, 0.4);
            border: 1px solid var(--border-color);
            border-radius: 10px;
            padding: 1.25rem 1.5rem;
            font-family: 'Courier New', monospace;
            font-size: 0.88rem;
            line-height: 1.8;
            overflow-x: auto;
            margin: 1rem 0;
            position: relative;
            color: #94a3b8;
        }

        html[data-theme="light"] .code-block {
            background: rgba(15, 23, 42, 0.04);
        }

        .code-block .comment {
            color: #475569;
            font-style: italic;
        }

        .code-block .keyword {
            color: var(--clr-accent-text);
            font-weight: 700;
        }

        .code-block .number {
            color: var(--warning-text);
        }

        .code-block .label {
            color: var(--clr-accent2-text);
            font-weight: 700;
        }

        .code-label {
            position: absolute;
            top: 8px;
            right: 12px;
            background: rgba(255, 255, 255, 0.06);
            color: var(--clr-muted);
            font-size: 0.72rem;
            padding: 2px 8px;
            border-radius: 4px;
            font-family: 'Segoe UI', sans-serif;
        }

        /* ── Accordion ── */
        .accordion {
            border: 1px solid var(--border-color);
            border-radius: var(--radius);
            overflow: hidden;
            margin-bottom: 1rem;
        }

        .accordion-header {
            background: var(--box-bg);
            padding: 1rem 1.25rem;
            cursor: pointer;
            display: flex;
            justify-content: space-between;
            align-items: center;
            font-weight: 600;
            font-size: 0.95rem;
            color: var(--clr-text);
            transition: var(--transition-fast);
            border: none;
            width: 100%;
            text-align: left;
            font-family: inherit;
        }

        .accordion-header:hover {
            background: rgba(52, 211, 153, 0.07);
            color: var(--clr-accent-text);
        }

        .accordion-header.open {
            background: rgba(52, 211, 153, 0.1);
            color: var(--clr-accent-text);
            border-bottom: 1px solid var(--border-color);
        }

        .accordion-arrow {
            transition: transform 0.25s ease;
            color: var(--clr-muted);
        }

        .accordion-header.open .accordion-arrow {
            transform: rotate(180deg);
        }

        .accordion-body {
            padding: 1.25rem;
            display: none;
            background: var(--panel-bg);
        }

        .accordion-body.open {
            display: block;
        }

        /* ── Highlight / Info-Boxen ── */
        .highlight-box {
            background: rgba(52, 211, 153, 0.06);
            border: 1px solid rgba(52, 211, 153, 0.2);
            border-left: 4px solid var(--clr-accent);
            border-radius: 8px;
            padding: 1rem 1.25rem;
            margin: 1rem 0;
        }

        .highlight-box h4 {
            color: var(--clr-accent-text);
            margin-bottom: 0.5rem;
            font-size: 0.95rem;
        }

        .highlight-box p,
        .highlight-box li {
            color: var(--clr-muted);
            font-size: 0.9rem;
            line-height: 1.6;
        }

        .highlight-box ol,
        .highlight-box ul {
            padding-left: 1.25rem;
            margin-top: 0.4rem;
        }

        .highlight-box li {
            margin-bottom: 0.3rem;
        }

        .info-box-accent {
            background: rgba(56, 189, 248, 0.07);
            border: 1px solid rgba(56, 189, 248, 0.2);
            border-left: 4px solid var(--clr-accent2);
            border-radius: 8px;
            padding: 1rem 1.25rem;
            margin: 1rem 0;
            font-size: 0.9rem;
            color: var(--clr-muted);
        }

        .info-box-accent strong {
            display: block;
            color: var(--clr-accent2-text);
            margin-bottom: 0.3rem;
        }

        .info-box-warn {
            background: rgba(251, 191, 36, 0.06);
            border: 1px solid rgba(251, 191, 36, 0.2);
            border-left: 4px solid var(--warning);
            border-radius: 8px;
            padding: 1rem 1.25rem;
            margin: 1rem 0;
            font-size: 0.9rem;
            color: var(--clr-muted);
        }

        .info-box-warn strong {
            display: block;
            color: var(--warning-text);
            margin-bottom: 0.3rem;
        }

        /* ── Speicher-Visualisierung ── */
        .memory-vis {
            display: flex;
            gap: 1.25rem;
            flex-wrap: wrap;
            margin: 1rem 0;
        }

        .memory-block {
            flex: 1;
            min-width: 200px;
        }

        .memory-table {
            width: 100%;
            border-collapse: collapse;
            font-family: 'Courier New', monospace;
            font-size: 0.85rem;
        }

        .memory-table th {
            background: rgba(52, 211, 153, 0.15);
            color: var(--clr-accent-text);
            padding: 6px 10px;
            text-align: center;
            font-weight: 700;
        }

        .memory-table td {
            padding: 5px 10px;
            border: 1px solid var(--border-color);
            text-align: center;
            color: var(--clr-muted);
        }

        .memory-table .addr {
            color: var(--clr-muted);
            font-size: 0.78rem;
        }

        .memory-table .instr {
            color: var(--clr-accent-text);
            font-weight: 700;
            background: rgba(52, 211, 153, 0.05);
        }

        .memory-table .data {
            color: var(--clr-accent2-text);
            background: rgba(56, 189, 248, 0.05);
        }

        .memory-table .ip-row td {
            background: rgba(251, 191, 36, 0.08) !important;
        }

        /* ── Two-Column ── */
        .two-col {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1rem;
        }

        @media (max-width: 600px) {
            .two-col {
                grid-template-columns: 1fr;
            }
        }

        .col-box {
            border-radius: 10px;
            padding: 1rem;
        }

        .col-box.accent-green {
            background: rgba(52, 211, 153, 0.07);
            border: 1px solid rgba(52, 211, 153, 0.2);
        }

        .col-box.accent-blue {
            background: rgba(56, 189, 248, 0.07);
            border: 1px solid rgba(56, 189, 248, 0.2);
        }

        .col-box h4 {
            margin-bottom: 0.6rem;
            font-size: 0.95rem;
        }

        .col-box.accent-green h4 {
            color: var(--clr-accent-text);
        }

        .col-box.accent-blue h4 {
            color: var(--clr-accent2-text);
        }

        .col-box ul {
            padding-left: 1.1rem;
            font-size: 0.88rem;
            color: var(--clr-muted);
        }

        .col-box li {
            margin-bottom: 0.3rem;
            line-height: 1.5;
        }

        /* ── Chip ── */
        .chip {
            display: inline-block;
            background: rgba(56, 189, 248, 0.12);
            color: var(--clr-accent2-text);
            border: 1px solid rgba(56, 189, 248, 0.25);
            padding: 1px 7px;
            border-radius: 4px;
            font-size: 0.8rem;
            font-weight: 600;
            margin: 1px;
        }

        /* ── Step-List ── */
        .step-list {
            counter-reset: steps;
            list-style: none;
            padding: 0;
            margin: 0.75rem 0;
        }

        .step-list li {
            counter-increment: steps;
            display: flex;
            align-items: flex-start;
            gap: 0.75rem;
            margin-bottom: 0.75rem;
            font-size: 0.9rem;
            color: var(--clr-muted);
            line-height: 1.5;
        }

        .step-list li::before {
            content: counter(steps);
            background: linear-gradient(135deg, var(--clr-accent), var(--clr-accent2));
            color: var(--clr-on-accent);
            min-width: 24px;
            height: 24px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 0.78rem;
            font-weight: 800;
            flex-shrink: 0;
            margin-top: 1px;
        }

        /* ── Styled Lists ── */
        ul.styled,
        ol.styled {
            padding-left: 1.25rem;
            margin: 0.5rem 0;
            color: var(--clr-muted);
            font-size: 0.92rem;
        }

        ul.styled li,
        ol.styled li {
            margin-bottom: 0.4rem;
            line-height: 1.55;
        }

        /* ============================================================
           FIRMWARE-REITER
        ============================================================ */

        /* Suchleiste */
        .fw-search-bar {
            display: flex;
            gap: 0.75rem;
            margin-bottom: 1.5rem;
            flex-wrap: wrap;
            align-items: center;
        }

        .fw-search-input {
            flex: 1;
            min-width: 200px;
            padding: 0.65rem 1rem;
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: 999px;
            color: var(--clr-text);
            font-family: inherit;
            font-size: 0.92rem;
            transition: border-color 0.2s;
        }

        .fw-search-input:focus {
            outline: none;
            border-color: var(--clr-accent2);
        }

        .fw-filter-select {
            padding: 0.65rem 1rem;
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: 999px;
            color: var(--clr-text);
            font-family: inherit;
            font-size: 0.88rem;
            cursor: pointer;
            transition: border-color 0.2s;
        }

        .fw-filter-select:focus {
            outline: none;
            border-color: var(--clr-accent);
        }

        .fw-count {
            font-size: 0.82rem;
            color: var(--clr-muted);
            white-space: nowrap;
        }

        /* Firmware-Tabelle */
        .fw-table-wrapper {
            overflow-x: auto;
            border-radius: var(--radius);
            border: 1px solid var(--border-color);
            box-shadow: var(--shadow-sm);
        }

        .fw-table {
            width: 100%;
            border-collapse: collapse;
            font-size: 0.85rem;
            min-width: 700px;
        }

        .fw-table thead tr {
            background: rgba(52, 211, 153, 0.12);
            border-bottom: 2px solid var(--clr-accent);
        }

        .fw-table th {
            padding: 0.7rem 0.9rem;
            text-align: left;
            font-weight: 700;
            color: var(--clr-accent-text);
            white-space: nowrap;
        }

        .fw-table th.center {
            text-align: center;
        }

        .fw-table td {
            padding: 0.55rem 0.9rem;
            border-bottom: 1px solid var(--border-color);
            color: var(--clr-muted);
            vertical-align: middle;
        }

        .fw-table tr:last-child td {
            border-bottom: none;
        }

        .fw-table tr:hover td {
            background: var(--box-bg);
            color: var(--clr-text);
        }

        .fw-table tr.fw-group-header td {
            background: rgba(56, 189, 248, 0.06);
            color: var(--clr-accent2-text);
            font-weight: 700;
            font-size: 0.8rem;
            text-transform: uppercase;
            letter-spacing: 0.06em;
            padding: 0.45rem 0.9rem;
            border-bottom: 1px solid rgba(56, 189, 248, 0.2);
        }

        .fw-table tr.fw-hidden {
            display: none;
        }

        /* Opcode-Badge */
        .op-badge {
            display: inline-block;
            background: rgba(52, 211, 153, 0.12);
            color: var(--clr-accent-text);
            border: 1px solid rgba(52, 211, 153, 0.25);
            padding: 2px 8px;
            border-radius: 5px;
            font-family: 'Courier New', monospace;
            font-size: 0.88rem;
            font-weight: 700;
            letter-spacing: 0.04em;
        }

        .mnem-badge {
            font-family: 'Courier New', monospace;
            font-size: 0.88rem;
            color: var(--clr-text);
            font-weight: 600;
        }

        .fw-addr {
            font-family: 'Courier New', monospace;
            font-size: 0.82rem;
            color: var(--clr-muted);
        }

        /* Mikro-Steps Visualisierung */
        .micro-steps {
            display: flex;
            flex-wrap: wrap;
            gap: 4px;
        }

        .micro-step {
            display: inline-block;
            background: var(--box-bg);
            border: 1px solid var(--border-color);
            border-radius: 4px;
            padding: 1px 6px;
            font-family: 'Courier New', monospace;
            font-size: 0.75rem;
            color: var(--clr-muted);
        }

        .micro-step.active {
            background: rgba(56, 189, 248, 0.1);
            border-color: rgba(56, 189, 248, 0.3);
            color: var(--clr-accent2-text);
        }

        /* Kategorien-Legende */
        .fw-legend {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin-bottom: 1rem;
        }

        .fw-legend-item {
            display: flex;
            align-items: center;
            gap: 0.4rem;
            font-size: 0.8rem;
            color: var(--clr-muted);
            padding: 3px 10px;
            border-radius: 999px;
            border: 1px solid var(--border-color);
            background: var(--panel-bg);
            cursor: pointer;
            transition: var(--transition-fast);
        }

        .fw-legend-item:hover,
        .fw-legend-item.active {
            border-color: var(--clr-accent);
            color: var(--clr-text);
        }

        .fw-legend-dot {
            width: 8px;
            height: 8px;
            border-radius: 50%;
            flex-shrink: 0;
        }

        /* Detail-Panel */
        .fw-detail-panel {
            background: var(--panel-bg);
            border: 1px solid var(--clr-accent);
            border-radius: var(--radius);
            padding: 1.25rem 1.5rem;
            margin-bottom: 1.5rem;
            display: none;
            animation: fadeIn 0.2s ease;
            position: relative;
        }

        .fw-detail-panel.show {
            display: block;
        }

        .fw-detail-close {
            position: absolute;
            top: 0.75rem;
            right: 1rem;
            background: none;
            border: none;
            font-size: 1.2rem;
            cursor: pointer;
            color: var(--clr-muted);
            font-family: inherit;
            transition: color 0.2s;
        }

        .fw-detail-close:hover {
            color: var(--danger-text);
        }

        .fw-detail-title {
            font-size: 1.1rem;
            font-weight: 700;
            color: var(--clr-accent-text);
            margin-bottom: 0.75rem;
            font-family: 'Courier New', monospace;
        }

        .fw-detail-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
            gap: 0.75rem;
            margin-bottom: 1rem;
        }

        .fw-detail-item {
            background: var(--box-bg);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 0.65rem 1rem;
        }

        .fw-detail-item-label {
            font-size: 0.72rem;
            text-transform: uppercase;
            letter-spacing: 0.06em;
            color: var(--clr-muted);
            margin-bottom: 0.25rem;
            font-weight: 700;
        }

        .fw-detail-item-value {
            font-family: 'Courier New', monospace;
            font-size: 0.92rem;
            color: var(--clr-text);
            font-weight: 600;
        }

        /* Firmware-Rohansicht */
        .fw-raw-block {
            background: rgba(0, 0, 0, 0.35);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 0.75rem 1rem;
            font-family: 'Courier New', monospace;
            font-size: 0.78rem;
            color: var(--clr-muted);
            line-height: 1.7;
            overflow-x: auto;
            white-space: pre;
            max-height: 220px;
        }

        html[data-theme="light"] .fw-raw-block {
            background: rgba(15, 23, 42, 0.04);
        }

        .fw-raw-block .fw-raw-addr {
            color: var(--warning-text);
        }

        .fw-raw-block .fw-raw-mnem {
            color: var(--clr-accent-text);
            font-weight: 700;
        }

        .fw-raw-block .fw-raw-bits {
            color: var(--clr-accent2-text);
        }

        .fw-raw-block .fw-raw-next {
            color: #a78bfa;
        }

        /* Mikrooperation-Legende */
        .micro-legend {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
            gap: 0.5rem;
            margin-top: 0.75rem;
        }

        .micro-legend-item {
            background: var(--box-bg);
            border: 1px solid var(--border-color);
            border-radius: 6px;
            padding: 0.4rem 0.7rem;
            font-size: 0.78rem;
            display: flex;
            gap: 0.5rem;
            align-items: center;
        }

        .micro-legend-key {
            font-family: 'Courier New', monospace;
            font-weight: 700;
            color: var(--clr-accent2-text);
            min-width: 16px;
        }

        .micro-legend-val {
            color: var(--clr-muted);
        }

        /* ============================================================
           ÜBUNGS-REITER
        ============================================================ */

        .stats-bar {
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: var(--radius);
            padding: 1rem 1.5rem;
            margin-bottom: 1.5rem;
            display: flex;
            align-items: center;
            gap: 1.5rem;
            flex-wrap: wrap;
            box-shadow: var(--shadow-sm);
        }

        .stat-item {
            display: flex;
            flex-direction: column;
            align-items: center;
            min-width: 70px;
        }

        .stat-value {
            font-size: 1.6rem;
            font-weight: 800;
            background: linear-gradient(135deg, var(--clr-accent), var(--clr-accent2));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .stat-label {
            font-size: 0.72rem;
            color: var(--clr-muted);
            text-align: center;
            line-height: 1.3;
        }

        .stat-divider {
            width: 1px;
            height: 40px;
            background: var(--border-color);
        }

        .difficulty-filter {
            display: flex;
            gap: 0.5rem;
            margin-bottom: 1.5rem;
            flex-wrap: wrap;
        }

        .diff-btn {
            padding: 0.5rem 1.1rem;
            border-radius: 999px;
            border: 1px solid var(--border-color);
            background: var(--panel-bg);
            cursor: pointer;
            font-size: 0.85rem;
            font-weight: 600;
            color: var(--clr-muted);
            font-family: inherit;
            transition: var(--transition-fast);
        }

        .diff-btn:hover {
            color: var(--clr-text);
            border-color: var(--clr-muted);
        }

        .diff-btn.active.all {
            background: linear-gradient(135deg, var(--clr-accent), var(--clr-accent2));
            color: var(--clr-on-accent);
            border-color: transparent;
        }

        .diff-btn.active.easy {
            background: rgba(52, 211, 153, 0.15);
            color: var(--clr-accent-text);
            border-color: var(--clr-accent);
        }

        .diff-btn.active.medium {
            background: rgba(251, 191, 36, 0.15);
            color: var(--warning-text);
            border-color: var(--warning);
        }

        .diff-btn.active.hard {
            background: rgba(248, 113, 113, 0.15);
            color: var(--danger-text);
            border-color: var(--danger);
        }

        .exercise-card {
            background: var(--panel-bg);
            border: 1px solid var(--border-color);
            border-radius: var(--radius);
            margin-bottom: 1.25rem;
            overflow: hidden;
            box-shadow: var(--shadow-sm);
            transition: var(--transition-fast);
        }

        .exercise-card:hover {
            box-shadow: var(--shadow);
        }

        .exercise-header {
            padding: 1rem 1.25rem;
            display: flex;
            align-items: center;
            gap: 0.75rem;
            border-bottom: 1px solid var(--border-color);
        }

        .exercise-num {
            width: 32px;
            height: 32px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 800;
            font-size: 0.88rem;
            flex-shrink: 0;
        }

        .exercise-num.easy {
            background: rgba(52, 211, 153, 0.15);
            color: var(--clr-accent-text);
        }

        .exercise-num.medium {
            background: rgba(251, 191, 36, 0.15);
            color: var(--warning-text);
        }

        .exercise-num.hard {
            background: rgba(248, 113, 113, 0.15);
            color: var(--danger-text);
        }

        .exercise-title {
            font-weight: 700;
            font-size: 0.98rem;
            flex: 1;
            color: var(--clr-text);
        }

        .diff-badge {
            padding: 2px 10px;
            border-radius: 999px;
            font-size: 0.72rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 0.05em;
        }

        .diff-badge.easy {
            background: rgba(52, 211, 153, 0.15);
            color: var(--clr-accent-text);
        }

        .diff-badge.medium {
            background: rgba(251, 191, 36, 0.15);
            color: var(--warning-text);
        }

        .diff-badge.hard {
            background: rgba(248, 113, 113, 0.15);
            color: var(--danger-text);
        }

        .exercise-body {
            padding: 1.25rem;
        }

        .exercise-body>p {
            color: var(--clr-muted);
            font-size: 0.92rem;
            margin-bottom: 0.75rem;
            line-height: 1.6;
        }

        .mc-options {
            display: flex;
            flex-direction: column;
            gap: 0.5rem;
            margin-top: 0.75rem;
        }

        .mc-option {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            padding: 0.75rem 1rem;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            cursor: pointer;
            transition: var(--transition-fast);
            font-size: 0.9rem;
            color: var(--clr-muted);
            background: var(--box-bg);
        }

        .mc-option:hover {
            border-color: var(--clr-accent2);
            color: var(--clr-text);
            background: rgba(56, 189, 248, 0.05);
        }

        .mc-option input {
            margin: 0;
            cursor: pointer;
            accent-color: var(--clr-accent);
        }

        .mc-option.correct {
            border-color: var(--clr-accent);
            background: rgba(52, 211, 153, 0.08);
            color: var(--clr-accent-text);
        }

        .mc-option.wrong {
            border-color: var(--danger);
            background: rgba(248, 113, 113, 0.08);
            color: var(--danger-text);
        }

        .exercise-actions {
            display: flex;
            gap: 0.6rem;
            margin-top: 1rem;
            flex-wrap: wrap;
        }

        .btn {
            padding: 0.55rem 1.2rem;
            border-radius: 8px;
            border: 1px solid var(--border-color);
            cursor: pointer;
            font-size: 0.88rem;
            font-weight: 600;
            font-family: inherit;
            transition: var(--transition-fast);
        }

        .btn-primary {
            background: linear-gradient(135deg, var(--clr-accent), var(--clr-accent2));
            color: var(--clr-on-accent);
            border: none;
        }

        .btn-primary:hover {
            box-shadow: 0 4px 15px rgba(52, 211, 153, 0.25);
            transform: translateY(-1px);
        }

        .btn-secondary {
            background: var(--box-bg);
            color: var(--clr-muted);
        }

        .btn-secondary:hover {
            color: var(--clr-text);
            border-color: var(--clr-muted);
        }

        .solution-box {
            display: none;
            margin-top: 1rem;
            padding: 1rem 1.25rem;
            background: rgba(52, 211, 153, 0.06);
            border-radius: 10px;
            border: 1px solid rgba(52, 211, 153, 0.2);
            border-left: 4px solid var(--clr-accent);
        }

        .solution-box.show {
            display: block;
            animation: fadeIn 0.25s ease;
        }

        .solution-box h4 {
            color: var(--clr-accent-text);
            margin-bottom: 0.6rem;
            font-size: 0.92rem;
        }

        .solution-box p,
        .solution-box li {
            color: var(--clr-muted);
            font-size: 0.9rem;
            line-height: 1.6;
        }

        .solution-box ul {
            padding-left: 1.1rem;
            margin-top: 0.4rem;
        }

        .solution-box li {
            margin-bottom: 0.3rem;
        }

        .feedback {
            display: none;
            margin-top: 0.75rem;
            padding: 0.65rem 1rem;
            border-radius: 8px;
            font-size: 0.9rem;
            font-weight: 600;
        }

        .feedback.correct {
            display: block;
            background: rgba(52, 211, 153, 0.1);
            color: var(--clr-accent-text);
            border: 1px solid rgba(52, 211, 153, 0.25);
        }

        .feedback.wrong {
            display: block;
            background: rgba(248, 113, 113, 0.1);
            color: var(--danger-text);
            border: 1px solid rgba(248, 113, 113, 0.25);
        }

        .answer-area {
            width: 100%;
            min-height: 110px;
            font-family: 'Courier New', monospace;
            font-size: 0.88rem;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 0.75rem 1rem;
            resize: vertical;
            background: var(--box-bg);
            color: var(--clr-text);
            transition: border-color 0.2s;
            margin-top: 0.5rem;
        }

        .answer-area:focus {
            outline: none;
            border-color: var(--clr-accent2);
            background: rgba(56, 189, 248, 0.03);
        }

        .trace-table {
            width: 100%;
            border-collapse: collapse;
            font-family: 'Courier New', monospace;
            font-size: 0.83rem;
            margin: 0.75rem 0;
            overflow-x: auto;
            display: block;
        }

        .trace-table th {
            background: rgba(52, 211, 153, 0.12);
            color: var(--clr-accent-text);
            padding: 7px 10px;
            text-align: center;
            white-space: nowrap;
            font-weight: 700;
        }

        .trace-table td {
            padding: 6px 10px;
            border: 1px solid var(--border-color);
            text-align: center;
            background: var(--panel-bg);
            color: var(--clr-muted);
        }

        .trace-table td.given {
            background: var(--box-bg);
        }

        .trace-input {
            width: 58px;
            border: 1px solid var(--border-color);
            border-radius: 5px;
            padding: 3px 5px;
            font-family: 'Courier New', monospace;
            font-size: 0.83rem;
            text-align: center;
            background: rgba(251, 191, 36, 0.06);
            color: var(--clr-text);
        }

        .trace-input:focus {
            outline: none;
            border-color: var(--clr-accent2);
        }

        .progress-bar {
            flex: 1;
            min-width: 120px;
        }

        .progress-rail {
            background: var(--box-bg);
            border-radius: 999px;
            height: 7px;
            margin: 0.3rem 0;
            overflow: hidden;
            border: 1px solid var(--border-color);
        }

        .progress-fill {
            height: 100%;
            background: linear-gradient(90deg, var(--clr-accent), var(--clr-accent2));
            border-radius: 999px;
            transition: width 0.4s ease;
        }

        .progress-info {
            display: flex;
            justify-content: space-between;
            font-size: 0.78rem;
            color: var(--clr-muted);
        }

        .order-row {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            padding: 0.75rem 1rem;
            background: var(--box-bg);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            margin-bottom: 0.5rem;
            font-size: 0.9rem;
            color: var(--clr-muted);
        }

        .order-input {
            width: 48px;
            padding: 5px;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            text-align: center;
            font-family: inherit;
            font-size: 0.9rem;
            background: var(--panel-bg);
            color: var(--clr-text);
            flex-shrink: 0;
        }

        .order-input:focus {
            outline: none;
            border-color: var(--clr-accent2);
        }

        .addr-select {
            padding: 4px 8px;
            border: 1px solid var(--border-color);
            border-radius: 5px;
            font-size: 0.85rem;
            background: var(--panel-bg);
            color: var(--clr-text);
            font-family: inherit;
            cursor: pointer;
        }

        .addr-select:focus {
            outline: none;
            border-color: var(--clr-accent);
        }

        .num-input {
            width: 68px;
            padding: 5px 8px;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            text-align: center;
            font-size: 0.95rem;
            background: var(--panel-bg);
            color: var(--clr-text);
            font-family: 'Courier New', monospace;
        }

        .num-input:focus {
            outline: none;
            border-color: var(--clr-accent2);
        }

        .inline-ans {
            display: inline-block;
            width: 80px;
            padding: 5px 8px;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            text-align: center;
            font-size: 1rem;
            font-family: 'Courier New', monospace;
            background: var(--panel-bg);
            color: var(--clr-text);
            margin: 0 0.25rem;
        }

        .inline-ans:focus {
            outline: none;
            border-color: var(--clr-accent2);
        }

        @media (max-width: 768px) {
            .vn-diagram {
                grid-template-columns: 1fr;
            }

            .vn-block.cpu {
                grid-column: 1;
            }

            .vn-block.io-row {
                grid-column: 1;
            }

            .cycle-steps {
                flex-direction: column;
            }

            .cycle-step::after {
                display: none !important;
            }
        }