:root {
    --primary-bg: #f8fafc;
    --sidebar-bg: #ffffff;
    --card-bg: #ffffff;
    --accent-color: #6366f1;
    --accent-hover: #4f46e5;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Noto Sans TC', sans-serif;
}

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

body {
    font-family: var(--font-body);
    background-color: var(--primary-bg);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
}

/* Layout */
.app-container {
    display: flex;
    height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 320px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-sm);
    z-index: 10;
    transition: width 0.3s ease;
    position: relative;
}

.sidebar.collapsed {
    width: 50px; /* Small width just for the toggle button or creating space */
}

/* Hide content when collapsed */
.sidebar.collapsed .sidebar-content {
    display: none; /* Simplest way to hide */
}

.sidebar-content {
    display: flex;
    flex-direction: column;
    height: 100%;
    padding: 1.5rem;
    overflow: hidden; /* Prevent scrollbars during transition */
}

.sidebar-toggle {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: transparent;
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 4px;
    border-radius: 4px;
    z-index: 20;
}

.sidebar.collapsed .sidebar-toggle {
    right: auto;
    left: 50%;
    transform: translateX(-50%);
}

.sidebar-header {
    margin-bottom: 2rem;
    padding-right: 20px; /* Space for toggle */
}

.sidebar-header h1 {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}

.sidebar-header p {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.event-list {
    flex: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    padding-right: 0.5rem;
}

.event-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.event-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-color);
}

.event-card.active {
    border-color: var(--accent-color);
    background-color: #eef2ff; /* Light indigo */
    box-shadow: var(--shadow-md);
}

.event-card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.event-card p { /* Tag like 'Reflex' */
    font-size: 0.75rem;
    display: inline-block;
    padding: 0.25rem 0.5rem;
    border-radius: 999px;
    background-color: #e2e8f0;
    color: var(--text-secondary);
    font-weight: 500;
}

.sidebar-footer {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-align: center;
}

/* Workspace */
.workspace {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 2rem;
    gap: 2rem;
    overflow-y: auto;
}

.mission-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.mission-info h2 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

.mission-info p {
    color: var(--text-secondary);
}

.mission-controls {
    display: flex;
    gap: 1rem;
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
    font-family: var(--font-body);
}

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

.btn-primary:hover {
    background-color: var(--accent-hover);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-secondary {
    background-color: white;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
}

.btn-secondary:hover {
    background-color: #f1f5f9;
    color: var(--text-primary);
}

/* Sequence Area */
.sequence-area {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    min-height: 250px;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.pathway-container {
    display: flex;
    align-items: center;
    gap: 1rem;
    overflow-x: auto;
    padding-bottom: 1rem;
}

.start-point, .end-point {
    font-weight: 700;
    color: var(--text-secondary);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.5rem 1rem;
    background: #f1f5f9;
    border-radius: var(--radius-md);
    flex-shrink: 0;
}

.drop-zone {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 0.5rem; /* Gap between cards */
    min-height: 100px;
    padding: 1rem;
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-md);
    background-color: #fafbfc;
    transition: all 0.2s;
    overflow-x: auto;
}

.drop-zone.drag-over {
    border-color: var(--accent-color);
    background-color: #eef2ff;
}

.placeholder-text {
    flex: 1;
    text-align: center;
    color: #94a3b8;
    pointer-events: none;
    user-select: none;
}

/* Parts Bank */
.parts-bank-container {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.parts-bank-container h3 {
    margin-bottom: 1rem;
    font-size: 1rem;
    color: var(--text-secondary);
}

.parts-bank {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* Draggable Part Card */
.part-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.75rem 1.25rem;
    cursor: grab;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    box-shadow: var(--shadow-sm);
    transition: all 0.2s;
    user-select: none;
    min-width: 120px;
    justify-content: center;
}

.part-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-color);
}

.part-card:active {
    cursor: grabbing;
    transform: scale(0.98);
}

.part-card .icon {
    font-size: 1.25rem;
}

.part-card .name {
    font-weight: 500;
    font-size: 0.95rem;
}

/* Part Card Colors */
.part-card.central {
    background-color: #fee2e2; /* Light Red */
    border-color: #fca5a5;
    color: #991b1b;
}

.part-card.neuron {
    background-color: #e0f2fe; /* Light Blue */
    border-color: #7dd3fc;
    color: #075985;
}

.part-card.terminal {
    background-color: #dcfce7; /* Light Green */
    border-color: #86efac;
    color: #166534;
}

/* Hover effects for colored cards - slightly darker */
.part-card.central:hover { background-color: #fecaca; }
.part-card.neuron:hover { background-color: #bae6fd; }
.part-card.terminal:hover { background-color: #bbf7d0; }

/* Card in Sequence */
.drop-zone .part-card {
    background: white;
    border: 1px solid var(--accent-color);
    box-shadow: var(--shadow-md);
}

/* Override dragging colors to keep them in sequence? 
   Actually, the user probably wants them to keep their color in the sequence too.
   The previous CSS enforced white background in drop-zone. I should remove that enforcement 
   or allow the specific classes to override it.
*/
.drop-zone .part-card.central {
    background-color: #fee2e2;
    border-color: #fca5a5;
    color: #991b1b;
}
.drop-zone .part-card.neuron {
    background-color: #e0f2fe;
    border-color: #7dd3fc;
    color: #075985;
}
.drop-zone .part-card.terminal {
    background-color: #dcfce7;
    border-color: #86efac;
    color: #166534;
}

.drop-zone .arrow-separator {
    color: var(--text-secondary);
    font-size: 1.25rem;
    font-weight: bold;
}

/* Feedback */
.feedback-area {
    padding: 1rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    text-align: center;
    animation: fadeIn 0.3s ease;
}

.feedback-area.success {
    background-color: #d1fae5;
    color: #065f46;
    border: 1px solid #6ee7b7;
}

.feedback-area.error {
    background-color: #fee2e2;
    color: #991b1b;
    border: 1px solid #fca5a5;
}

.hidden {
    display: none;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}