:root {
    --bg-color: #0d1117;
    --panel-bg: #161b22;
    --accent-color: #58a6ff;
    --text-primary: #c9d1d9;
    --text-secondary: #8b949e;
    --border-color: #30363d;
    --x-color: #58a6ff;
    --h-color: #ff7b72;
    --mult-color: #d2a8ff;
    --conv-color: #3fb950;
    --pos-fill: rgba(63, 185, 80, 0.4);
    --neg-fill: rgba(255, 123, 114, 0.4);
    --hover-bg: #21262d;
}

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

body {
    font-family: 'Inter', 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%;
    width: 100%;
    max-width: 1800px;
    margin: 0 auto;
}

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);
}

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

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

.tool-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
    font-weight: 500;
}

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

.tool-btn.active {
    border-color: var(--accent-color);
    color: var(--accent-color);
    box-shadow: 0 0 8px rgba(88, 166, 255, 0.4);
}

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

.left-pane,
.right-pane {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    min-width: 0;
}

.left-pane {
    flex: 1;
}

.right-pane {
    flex: 1.5;
}

.panel {
    background: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    flex: 1;
    min-width: 0;
    overflow: hidden;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
}

.panel-header {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

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

.panel-header-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
}

.preset-select {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 5px 10px;
    border-radius: 6px;
    font-size: 0.8rem;
    font-family: 'Inter', sans-serif;
    cursor: pointer;
    transition: border-color 0.2s;
    outline: none;
}

.preset-select:hover,
.preset-select:focus {
    border-color: var(--accent-color);
}

.subtitle {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 4px;
    display: block;
}

.canvas-wrapper {
    flex: 1;
    min-width: 0;
    min-height: 0;
    position: relative;
    overflow: hidden;
}

.left-pane .canvas-wrapper {
    cursor: crosshair;
}

#tau-canvas {
    cursor: ew-resize;
}

#mult-canvas,
#conv-canvas {
    cursor: default;
}

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

@media (max-width: 900px) {
    body {
        overflow: auto;
        height: auto;
        min-height: 100vh;
    }

    .workspace {
        flex-direction: column;
        overflow: visible;
    }

    .left-pane,
    .right-pane {
        flex: none;
    }

    .panel {
        min-height: 300px;
    }

    header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
        position: relative;
    }

    #btn-back {
        position: absolute;
        top: 1rem;
        right: 1.5rem;
    }
}