:root {
    /* Default Theme: Classic Purple */
    --bg-color: #1A1A1D;
    --surface-color: #2C2C2E;
    --primary-accent: #6668ad;
    --title-color: #C392FF;
    --text-color: #EAEAEA;
    --text-muted: #9E9E9E;
    --border-color: #3a3a3c;

    --bar-default-color: var(--primary-accent);
    --bar-done-color: #1DE9B6;
    --bar-compare-color: #FFEE58;
    --bar-swap-color: #FF5252;
    --bar-pivot-color: #536DFE;
    --bar-found-color: #00E676;

    --button-start-color: #1DE9B6;
    --button-stop-color: #FF6A8A;
    --button-step-color: #536DFE;
    --button-mute-color: #9E9E9E;
    --slider-thumb-color: var(--primary-accent);
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 1em;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 1em 1em 1em;
    border-bottom: 1px solid var(--border-color);
}

h1 {
    color: var(--title-color);
    font-weight: 600;
    letter-spacing: 1px;
    margin: 0;
}

#main-container {
    display: grid;
    grid-template-columns: 1fr 400px;
    grid-template-rows: auto 1fr;
    grid-template-areas:
        "viz controls"
        "viz info";
    gap: 20px;
    flex-grow: 1;
    padding-top: 20px;
    max-height: calc(100vh - 100px);
}

.viz-area {
    grid-area: viz;
    display: flex;
    gap: 10px;
    min-height: 400px;
}

.canvas-container { flex: 1; min-width: 0; }
canvas {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    width: 100%;
    height: 100%;
    border-radius: 8px;
}

.controls-area {
    grid-area: controls;
    background-color: var(--surface-color);
    padding: 20px;
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.info-area {
    grid-area: info;
}

.main-controls { display: flex; gap: 15px; }
.main-controls button {
    flex-grow: 1;
    padding: 10px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: filter 0.2s, transform 0.1s;
    display: flex;
    justify-content: center;
    align-items: center;
}
.main-controls svg { width: 24px; height: 24px; fill: #000; }

#startButton { background-color: var(--button-start-color); }
#stopButton { background-color: var(--button-stop-color); }
#stepButton { background-color: var(--button-step-color); }
#muteButton { background-color: var(--button-mute-color); }

fieldset {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 15px;
    margin: 0;
    background-color: var(--surface-color);
    min-width: 0;
}
legend {
    color: var(--title-color);
    font-weight: 600;
    padding: 0 10px;
}

#algo-selectors { display: flex; gap: 15px; }
#algo-selectors fieldset { flex: 1; }

.control-group { display: flex; flex-direction: column; gap: 8px; }
.control-group.slider-group { min-width: 180px; }
label { font-size: 0.9em; color: var(--text-muted); }

select, input[type="number"], textarea {
    background-color: #3E3E42;
    color: var(--text-color);
    border: 1px solid #555;
    border-radius: 6px;
    padding: 8px 12px;
    font-family: inherit;
    width: 100%;
    box-sizing: border-box;
}
textarea { resize: vertical; }

#stats-display p { margin: 0 0 10px 0; }
#stats-display p:last-child { margin-bottom: 0; }
#stats-display strong { color: var(--title-color); }

.tooltip {
    display: inline-block;
    background-color: var(--text-muted);
    color: var(--bg-color);
    border-radius: 50%;
    width: 16px;
    height: 16px;
    text-align: center;
    font-size: 12px;
    line-height: 16px;
    cursor: help;
    position: relative;
}
.tooltip:hover::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    background-color: #333;
    color: #fff;
    padding: 8px 12px;
    border-radius: 6px;
    z-index: 100;
    width: 200px;
    text-align: left;
    font-size: 0.85em;
    font-family: 'Poppins', sans-serif;
}

.toast {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--bar-swap-color);
    color: #000;
    padding: 15px 25px;
    border-radius: 8px;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s;
}
.toast.show { opacity: 1; visibility: visible; }

@media (max-width: 1200px) {
    #main-container {
        grid-template-columns: 1fr;
        grid-template-areas:
            "controls"
            "viz"
            "info";
        max-height: none;
    }
    .viz-area { min-height: 30vh; }
}