:root {
    --bg-color: #F4F4F0;
    --text-color: #000000;
    --border-color: #000000;
    --accent-color: #000000;
    --brand-blue: #003366;
    --grid-line: 1px solid var(--border-color);
    --font-mono: 'Courier New', Courier, monospace;
    --font-sans: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-sans);
    height: 100vh;
    overflow: hidden;
    /* App-like feel */
    display: flex;
    flex-direction: column;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100%;
    border: 2px solid var(--border-color);
    margin: var(--spacing-xs);
}

/* HEADER */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: var(--grid-line);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-color);
}

.brand h1 {
    font-family: var(--font-mono);
    font-size: 1.2rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.highlight {
    background: var(--brand-blue);
    color: var(--bg-color);
    padding: 0 4px;
}

/* NAV */
.main-nav {
    display: flex;
    gap: var(--spacing-xs);
}

.nav-btn {
    background: transparent;
    border: 1px solid transparent;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    cursor: pointer;
    padding: var(--spacing-xs) var(--spacing-sm);
    text-transform: uppercase;
}

.nav-btn:hover {
    text-decoration: underline;
}

.nav-btn.active {
    border: var(--grid-line);
    background: var(--brand-blue);
    color: var(--bg-color);
}

/* TABS */
.tab-content {
    display: none;
    flex: 1;
    overflow: hidden;
}

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

.split-pane {
    display: flex;
    width: 100%;
    height: 100%;
}

.panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    border-right: var(--grid-line);
    min-width: 0;
    /* Fix flex overflow issues */
}

/* 3-Column Layout Specifics */
#simulation .control-panel {
    flex: 0 0 280px;
    /* Fixed width for controls */
}

#simulation .visualization-panel {
    flex: 1;
    /* Flexible middle */
}

#simulation .results-panel {
    flex: 1.5;
    /* Graph gets more space */
    border-right: none;
}

#simulation .visualization-panel .canvas-container {
    border: none;
    border-top: var(--grid-line);
    border-bottom: var(--grid-line);
    margin: 0;
}

/* Ensure manipulation tab still works (2 columns) */
#manipulation .panel:last-child {
    border-right: none;
}

.panel-header {
    padding: var(--spacing-sm);
    border-bottom: var(--grid-line);
    background: var(--brand-blue);
    color: white;
}

.panel-header h2 {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    font-weight: bold;
    text-transform: uppercase;
}

/* LEFT PANEL CONTENT */
.controls-grid {
    display: flex;
    flex: 1;
    flex-direction: column;
    padding: var(--spacing-md);
    gap: var(--spacing-md);
    overflow-y: auto;
}

.canvas-container {
    background: #fff;
    border: var(--grid-line);
    position: relative;
    flex-grow: 1;
    min-height: 200px;
}

.setup-view canvas {
    width: 100%;
    height: 100%;
    display: block;
}

.overlay-info {
    position: absolute;
    bottom: var(--spacing-xs);
    left: var(--spacing-xs);
    background: var(--text-color);
    color: var(--bg-color);
    padding: 2px 6px;
    font-family: var(--font-mono);
    font-size: 1.1rem;
}

/* FORMS */
.params-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.input-group label {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    font-weight: bold;
}

select,
input[type="number"],
input[type="text"] {
    border: var(--grid-line);
    background: #fff;
    padding: 6px;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    border-radius: 0;
    -webkit-appearance: none;
    appearance: none;
}

select {
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23000000%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: right .7em top 50%;
    background-size: .65em auto;
    padding-right: 1.5em;
}

/* SLIDER */
.control-actions {
    border-top: var(--grid-line);
    padding-top: var(--spacing-sm);
    margin-top: var(--spacing-sm);
}

.control-actions label {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    font-weight: bold;
}

input[type=range] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    background: transparent;
}

input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    height: 16px;
    width: 16px;
    background: var(--brand-blue);
    cursor: pointer;
    margin-top: -6px;
    border-radius: 0;
    /* Square thumb for brutalist look */
}

input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: #ccc;
    border: 1px solid #000;
}

.digital-display {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    text-align: right;
    margin-top: var(--spacing-xs);
}

/* RESULTS PANEL */
.graph-container {
    flex: 2;
    background: #fff;
    margin: var(--spacing-md);
    border: var(--grid-line);
    position: relative;
    /* Grid background */
    background-image: linear-gradient(#eee 1px, transparent 1px), linear-gradient(90deg, #eee 1px, transparent 1px);
    background-size: 20px 20px;
}

canvas {
    width: 100%;
    height: 100%;
}

.data-readout {
    flex: 0 0 auto;
    border-top: var(--grid-line);
    padding: var(--spacing-md);
    display: flex;
    gap: var(--spacing-lg);
    justify-content: space-around;
    background: #F4F4F0;
}

.readout-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.readout-item .label {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: #555;
    margin-bottom: 4px;
}

.readout-item .value {
    font-family: var(--font-mono);
    font-size: 1.2rem;
    font-weight: bold;
}

/* TABLE STYLES */
.spreadsheet-container {
    flex: 1;
    overflow: auto;
    padding: var(--spacing-md);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-family: var(--font-mono);
    font-size: 0.9rem;
}

.data-table th {
    border: var(--grid-line);
    padding: 8px;
    background: #e0e0dc;
    text-align: center;
}

.data-table td {
    border: var(--grid-line);
    padding: 0;
}

.data-table input {
    width: 100%;
    border: none;
    text-align: center;
    padding: 8px;
    background: transparent;
}

.btn-row-add,
.btn-action {
    background: var(--brand-blue);
    color: var(--bg-color);
    border: none;
    padding: 8px 16px;
    font-family: var(--font-mono);
    cursor: pointer;
    margin-top: var(--spacing-sm);
}

.btn-action {
    background: #fff;
    color: #000;
    border: 1px solid #000;
    font-size: 0.7rem;
    margin: 0;
}

@media (max-width: 768px) {
    body {
        height: auto;
        overflow: auto;
    }

    .app-container {
        height: auto;
        border: none;
        margin: 0;
    }

    .split-pane {
        flex-direction: column;
    }

    .panel {
        border-right: none;
        border-bottom: var(--grid-line);
        height: auto;
        min-height: 400px;
        /* Ensure space for canvas */
    }

    .controls-grid {
        padding: var(--spacing-sm);
    }

    .canvas-container {
        min-height: 300px;
    }

    /* Hide simulation graph on very small screens in split view if needed, or stack */
}