:root {
    --bg-color: #ffffff;
    --panel-bg: #ffffff;
    --accent-color: #0969da;
    --text-primary: #000000;
    --text-secondary: #57606a;
    --border-color: #d0d7de;
    --pole-color: #cf222e;
    --zero-color: #0969da;
    --grid-color: #eaeef2;
    --axis-color: #24292f;
    --hover-bg: #f3f4f6;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100%;
    max-width: 1600px;
    margin: 0 auto;
    width: 100%;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--panel-bg);
    flex-wrap: wrap;
    gap: 1rem;
}

h1 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.controls {
    display: flex;
    gap: 1.5rem;
    align-items: center;
    flex-wrap: wrap;
}

.tool-group {
    display: flex;
    background: var(--bg-color);
    border-radius: 6px;
    padding: 2px;
    border: 1px solid var(--border-color);
}

.tool-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 6px 10px;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.tool-btn:hover {
    color: var(--text-primary);
    background-color: var(--hover-bg);
}

.tool-btn.active {
    color: var(--accent-color);
    background-color: rgba(88, 166, 255, 0.1);
}

.tool-btn.danger:hover {
    color: #f85149;
    background-color: rgba(248, 81, 73, 0.1);
}

.info-panel {
    font-family: 'SF Mono', monospace;
    font-size: 0.85rem;
    color: var(--text-secondary);
    min-width: 150px;
    text-align: right;
}

.workspace {
    display: flex;
    flex: 1;
    padding: 1.5rem;
    gap: 1.5rem;
    overflow: hidden;
}

.panel {
    background-color: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    flex: 1;
    overflow: hidden;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.panel-header {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: baseline;
}

.panel-header h2 {
    font-size: 1rem;
    font-weight: 500;
}

.subtitle {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.canvas-wrapper {
    flex: 1;
    position: relative;
    overflow: hidden;
    cursor: crosshair;
    display: flex;
    flex-direction: column;
}

#z-plane-wrapper {
    display: block;
    /* Z-plane is single canvas */
}

.hz-display {
    padding: 0.75rem 1rem;
    border-top: 1px solid var(--border-color);
    background: linear-gradient(135deg, #f8f9fb 0%, #f0f2f5 100%);
    text-align: center;
    overflow-x: auto;
    white-space: nowrap;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.25rem;
}

.hz-label {
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
}

#hz-formula .katex {
    font-size: 1.15rem;
}

.plot-container {
    flex: 1;
    position: relative;
    border-bottom: 1px solid var(--border-color);
    min-height: 0;
    /* Important for flex nested scrolling/sizing */
}

.plot-container:last-child {
    border-bottom: none;
}

.plot-label {
    position: absolute;
    top: 5px;
    right: 10px;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-secondary);
    background: rgba(255, 255, 255, 0.8);
    padding: 2px 6px;
    border-radius: 4px;
    pointer-events: none;
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
    touch-action: none;
    user-select: none;
    -webkit-user-select: none;
}

/* Responsive constraints */
@media (max-width: 768px) {
    .workspace {
        flex-direction: column;
        overflow-y: auto;
    }

    .panel {
        min-height: 400px;
        overflow-y: visible;
    }

    body {
        overflow-y: auto;
        height: auto;
    }

    .app-container {
        height: auto;
        min-height: 100vh;
    }

    header {
        flex-direction: column;
        align-items: flex-start;
    }
}