:root {
            --cpu-primary: #3b82f6;
            --cpu-secondary: #64748b;
            --cpu-accent: #10b981;
            --cpu-danger: #ef4444;
            --cpu-bg: #f8fafc;
            --cpu-panel: #ffffff;
            --cpu-border: #e2e8f0;
            --cpu-text: #1e293b;
            --cpu-text-muted: #64748b;
            --cpu-highlight: #fef3c7;
            --cpu-highlight-border: #f59e0b;
            --cpu-disabled: #f1f5f9;
        }

        .cpu-simulator-widget {
            font-family: 'Inter', sans-serif;
            background: var(--cpu-bg);
            border: 1px solid var(--cpu-border);
            border-radius: 12px;
            padding: 20px;
            box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
            max-width: 950px;
            margin: 0 auto;
            color: var(--cpu-text);
            box-sizing: border-box;
            user-select: none;
            position: relative; /* For modal positioning */
        }

        .cpu-simulator-widget * {
            box-sizing: border-box;
        }

        /* Toolbar & Header */
        .cpu-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 20px;
            flex-wrap: wrap;
            gap: 15px;
            padding-bottom: 15px;
            border-bottom: 1px solid var(--cpu-border);
        }

        .cpu-title {
            font-size: 1.25rem;
            font-weight: 700;
            color: var(--cpu-text);
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .cpu-controls-wrapper {
            display: flex;
            align-items: center;
            gap: 20px;
            flex-wrap: wrap;
        }

        .cpu-controls {
            display: flex;
            gap: 8px;
        }

        .cpu-btn {
            display: flex;
            align-items: center;
            gap: 6px;
            padding: 8px 16px;
            border-radius: 6px;
            border: 1px solid var(--cpu-border);
            background: var(--cpu-panel);
            color: var(--cpu-text);
            cursor: pointer;
            font-size: 0.875rem;
            font-weight: 600;
            transition: all 0.2s;
            box-shadow: 0 1px 2px rgba(0,0,0,0.05);
        }

        .cpu-btn:hover:not(:disabled) {
            background: #f1f5f9;
            border-color: #cbd5e1;
            transform: translateY(-1px);
        }

        .cpu-btn:disabled {
            opacity: 0.6;
            cursor: not-allowed;
            background: #f1f5f9;
            color: var(--cpu-text-muted);
        }

        .cpu-btn-primary {
            background: var(--cpu-primary);
            color: white;
            border-color: var(--cpu-primary);
        }

        .cpu-btn-primary:hover:not(:disabled) {
            background: #2563eb;
        }

        .cpu-btn-icon-only {
            padding: 8px;
        }

        /* Main Grid Layout */
        .cpu-main {
            display: grid;
            grid-template-columns: 340px 1fr;
            gap: 25px;
            align-items: start;
        }

        @media (max-width: 850px) {
            .cpu-main {
                grid-template-columns: 1fr;
            }
        }

        /* Memory Section */
        .cpu-section-title {
            font-size: 0.8rem;
            text-transform: uppercase;
            letter-spacing: 0.05em;
            color: var(--cpu-text-muted);
            margin-bottom: 10px;
            font-weight: 700;
            display: flex;
            justify-content: space-between;
        }

        .cpu-memory-container {
            background: var(--cpu-panel);
            border: 1px solid var(--cpu-border);
            border-radius: 8px;
            height: 421px; 
            overflow: visible; 
            display: flex;
            flex-direction: column;
            position: relative;
            z-index: 50; 
        }

        /* Memory Grid */
        .cpu-memory-header {
            display: grid;
            grid-template-columns: 40px 1.8fr 1.2fr;
            background: #f1f5f9;
            border-bottom: 1px solid var(--cpu-border);
            height: 35px;
            align-items: center;
            border-top-left-radius: 8px;
            border-top-right-radius: 8px;
        }

        .cpu-mem-head-cell {
            padding: 0 8px;
            font-size: 0.7rem;
            font-weight: 700;
            color: var(--cpu-text-muted);
            text-align: center;
            border-right: 1px solid var(--cpu-border);
        }

        .cpu-memory-row {
            display: grid;
            grid-template-columns: 40px 1.8fr 1.2fr;
            border-bottom: 1px solid var(--cpu-border);
            font-family: 'JetBrains Mono', monospace;
            font-size: 0.85rem;
            height: 32px; 
            transition: background 0.2s;
            position: relative;
            background: var(--cpu-panel);
        }

        .cpu-memory-row:last-child {
            border-bottom: none;
            border-bottom-left-radius: 8px;
            border-bottom-right-radius: 8px;
        }

        .cpu-memory-row.active {
            background: var(--cpu-highlight);
        }

        .cpu-memory-address {
            background: #f8fafc;
            color: var(--cpu-text-muted);
            display: flex;
            align-items: center;
            justify-content: center;
            border-right: 1px solid var(--cpu-border);
            font-size: 0.8rem;
        }

        /* Custom Instruction Control */
        .cpu-cell-instruction {
            padding: 0 0 0 8px;
            display: flex;
            align-items: center;
            border-right: 1px solid var(--cpu-border);
            position: relative;
        }
        
        .cpu-cell-instruction.has-command {
            color: var(--cpu-primary);
            font-weight: 600;
        }

        .cpu-instr-input {
            border: none;
            background: transparent;
            width: 100%;
            height: 100%;
            font-family: inherit;
            outline: none;
            color: inherit;
        }

        .cpu-instr-controls {
            width: 30px; 
            height: 100%;
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0;
        }

        .cpu-control-btn {
            background: transparent;
            border: none;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            height: 100%;
            width: 100%;
            padding: 0;
            color: var(--cpu-text-muted);
            transition: color 0.2s;
        }

        .cpu-control-btn:hover { color: var(--cpu-primary); }
        
        .cpu-control-btn.arrow-flip {
            transform: rotate(180deg);
        }

        .cpu-btn-clear {
            color: var(--cpu-danger);
            font-weight: bold;
        }
        .cpu-btn-clear:hover { background: #fee2e2; }

        /* Dropdown Menu */
        .cpu-dropdown-menu {
            position: absolute;
            top: 100%;
            left: 0;
            width: 100%;
            background: white;
            border: 1px solid var(--cpu-border);
            box-shadow: 0 4px 12px rgba(0,0,0,0.15);
            border-radius: 4px;
            z-index: 100;
            max-height: 200px;
            overflow-y: auto;
            display: none;
            padding-right: 16px; 
        }
        
        .cpu-dropdown-menu::-webkit-scrollbar {
            width: 30px; 
        }
        
        .cpu-dropdown-menu::-webkit-scrollbar-thumb {
            background-color: #cbd5e1;
            border-radius: 99px;
            border: 11px solid transparent; 
            background-clip: content-box;
        }
        
        .cpu-dropdown-menu::-webkit-scrollbar-track {
            background: transparent;
        }
        
        .cpu-dropdown-menu.open { display: block; }

        .cpu-dropdown-item {
            padding: 6px 9px; 
            cursor: pointer;
            color: var(--cpu-text);
            font-size: 0.85rem;
        }
        .cpu-dropdown-item:hover { background: #f1f5f9; }

        /* Custom Operand Spinner */
        .cpu-cell-operand {
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 0 8px;
        }

        .cpu-cell-operand.disabled {
            opacity: 0.3;
            pointer-events: none;
            background: #f8fafc;
        }

        .cpu-spinner-btn {
            width: 20px;
            height: 20px;
            border: 1px solid var(--cpu-border);
            background: white;
            border-radius: 4px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            color: var(--cpu-text-muted);
            font-size: 12px;
            line-height: 1;
        }
        .cpu-spinner-btn:hover { background: #f1f5f9; color: var(--cpu-primary); }

        .cpu-operand-val {
            flex-grow: 1;
            text-align: center;
            border: none;
            background: transparent;
            font-family: inherit;
            color: var(--cpu-text);
            width: 30px;
            outline: none;
        }

        /* CPU Internals Section */
        .cpu-internals {
            display: flex;
            flex-direction: column;
            gap: 20px;
        }

        /* Cycle Indicator */
        .cpu-cycle-status {
            display: flex;
            background: var(--cpu-panel);
            border: 1px solid var(--cpu-border);
            border-radius: 8px;
            overflow: hidden;
            height: 45px;
        }

        .cpu-cycle-step {
            flex: 1;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 0.8rem;
            font-weight: 600;
            color: var(--cpu-text-muted);
            border-right: 1px solid var(--cpu-border);
            transition: all 0.3s;
            letter-spacing: 0.05em;
        }

        .cpu-cycle-step:last-child {
            border-right: none;
        }

        .cpu-cycle-step.active {
            background: var(--cpu-primary);
            color: white;
        }

        /* Registers Grid */
        .cpu-registers {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 15px;
        }

        .cpu-register {
            background: var(--cpu-panel);
            border: 1px solid var(--cpu-border);
            border-radius: 8px;
            padding: 15px;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: space-between;
            position: relative;
            height: 120px;
        }

        .cpu-register.highlight {
            border-color: var(--cpu-highlight-border);
            background: var(--cpu-highlight);
            box-shadow: 0 0 0 2px var(--cpu-highlight-border);
        }

        .cpu-reg-label {
            font-size: 0.75rem;
            text-transform: uppercase;
            color: var(--cpu-text-muted);
            font-weight: 700;
            margin-bottom: 5px;
        }

        .cpu-reg-value {
            font-family: 'JetBrains Mono', monospace;
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--cpu-text);
        }

        .cpu-reg-desc {
            font-size: 0.7rem;
            color: var(--cpu-text-muted);
            text-align: center;
            margin-top: 5px;
        }

        /* Explanation Box */
        .cpu-explanation {
            background: #eff6ff;
            border: 1px solid #bfdbfe;
            color: #1e40af;
            border-radius: 8px;
            padding: 15px;
            font-size: 0.9rem;
            line-height: 1.5;
            min-height: 80px;
            display: flex;
            align-items: center;
            gap: 12px;
        }

        /* Output Console */
        .cpu-console {
            background: #1e293b;
            color: #10b981;
            border-radius: 8px;
            padding: 15px;
            font-family: 'JetBrains Mono', monospace;
            font-size: 0.9rem;
            height: 140px;
            overflow-y: auto;
            border: 1px solid var(--cpu-border);
            display: flex;
            flex-direction: column;
        }

        .cpu-console-title {
            color: #64748b;
            font-size: 0.75rem;
            text-transform: uppercase;
            margin-bottom: 10px;
            border-bottom: 1px solid #334155;
            padding-bottom: 5px;
            flex-shrink: 0;
        }

        .js-console-output {
            flex-grow: 1;
            overflow-y: auto;
        }
        
        /* Slider */
        .cpu-speed-control {
            display: flex;
            align-items: center;
            gap: 10px;
            font-size: 0.8rem;
            color: var(--cpu-text-muted);
            font-weight: 600;
        }
        
        input[type=range] {
            accent-color: var(--cpu-primary);
            width: 120px;
        }

        /* Modal Styles */
        .cpu-modal-overlay {
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: rgba(0,0,0,0.5);
            display: flex;
            align-items: center;
            justify-content: center;
            z-index: 1000;
            border-radius: 12px;
        }

        .cpu-modal {
            background: var(--cpu-panel);
            border: 1px solid var(--cpu-border);
            border-radius: 8px;
            padding: 20px;
            width: 300px;
            box-shadow: 0 10px 25px rgba(0,0,0,0.1);
        }

        .cpu-modal-header {
            font-weight: 700;
            font-size: 1.1rem;
            margin-bottom: 15px;
            color: var(--cpu-text);
        }

        .cpu-modal-body p {
            margin: 0 0 10px 0;
            color: var(--cpu-text-muted);
            font-size: 0.9rem;
        }

        .cpu-modal-input {
            width: 100%;
            padding: 10px;
            border: 1px solid var(--cpu-border);
            border-radius: 6px;
            font-size: 1rem;
            margin-bottom: 20px;
            background: var(--cpu-bg);
            color: var(--cpu-text);
        }

        .cpu-modal-input:focus {
            outline: none;
            border-color: var(--cpu-primary);
        }

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

        /* Dark Mode overrides */
        .cpu-simulator-widget.dark-mode {
            --cpu-bg: #0f172a;
            --cpu-panel: #1e293b;
            --cpu-border: #334155;
            --cpu-text: #f8fafc;
            --cpu-text-muted: #94a3b8;
            --cpu-highlight: #334155;
            --cpu-highlight-border: #60a5fa;
            --cpu-disabled: #172554;
        }
        
        .cpu-simulator-widget.dark-mode .cpu-memory-address,
        .cpu-simulator-widget.dark-mode .cpu-memory-header {
            background: #0f172a;
        }
        
        .cpu-simulator-widget.dark-mode .cpu-memory-row {
            background: #1e293b;
        }
        
        .cpu-simulator-widget.dark-mode .cpu-instr-input {
            color: #f8fafc;
        }

        .cpu-simulator-widget.dark-mode .cpu-cell-instruction.has-command {
            color: #60a5fa;
        }

        .cpu-simulator-widget.dark-mode .cpu-dropdown-menu {
            background: #1e293b;
            border-color: #334155;
        }
        
        .cpu-simulator-widget.dark-mode .cpu-dropdown-item:hover {
            background: #334155;
        }

        .cpu-simulator-widget.dark-mode .cpu-cell-operand.disabled {
            background: #0f172a;
        }

        .cpu-simulator-widget.dark-mode .cpu-spinner-btn {
            background: #1e293b;
            border-color: #334155;
            color: #94a3b8;
        }
        .cpu-simulator-widget.dark-mode .cpu-spinner-btn:hover {
            background: #334155;
            color: #60a5fa;
        }

        .cpu-simulator-widget.dark-mode .cpu-explanation {
            background: #172554;
            border-color: #1e40af;
            color: #dbeafe;
        }

        .cpu-simulator-widget.dark-mode .cpu-btn {
            background: #1e293b;
            border-color: #334155;
            color: #f8fafc;
        }
        
        .cpu-simulator-widget.dark-mode .cpu-btn:hover:not(:disabled) {
            background: #334155;
        }
        
        .cpu-simulator-widget.dark-mode .cpu-modal-input {
            background: #0f172a;
            border-color: #334155;
            color: #f8fafc;
        }