:root {
    /* Light Mode (Default) */
    --bg-color: #f0f2f5;
    --app-bg: white;
    --text-primary: #333;
    --text-secondary: #666;
    --heading-color: #333;
    --border-color: #ddd;

    --input-bg: white;
    --input-border: #ddd;

    --btn-primary-bg: #03c75a;
    --btn-primary-hover: #02b350;
    --btn-primary-text: white;

    --btn-secondary-bg: #e0e0e0;
    --btn-secondary-hover: #d0d0d0;
    --btn-secondary-text: #333;

    --canvas-bg: #fff;
    --canvas-border: #eee;

    --modal-overlay: rgba(0,0,0,0.5);
    --modal-bg: white;
    --modal-shadow: rgba(0,0,0,0.2);

    --list-border: #eee;

    /* Ladder Colors (for JS to reference or future use) */
    --ladder-line: #555;
    --ladder-text: #333;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #18191a;
        --app-bg: #242526;
        --text-primary: #e4e6eb;
        --text-secondary: #b0b3b8;
        --heading-color: #e4e6eb;
        --border-color: #3e4042;

        --input-bg: #3a3b3c;
        --input-border: #3e4042;

        /* Keep primary button green but maybe slightly desaturated? Naver green is iconic so keep it. */
        --btn-primary-bg: #03c75a;
        --btn-primary-hover: #02b350;
        --btn-primary-text: white;

        --btn-secondary-bg: #3a3b3c;
        --btn-secondary-hover: #4e4f50;
        --btn-secondary-text: #e4e6eb;

        --canvas-bg: #242526;
        --canvas-border: #3e4042;

        --modal-overlay: rgba(0,0,0,0.7);
        --modal-bg: #242526;
        --modal-shadow: rgba(0,0,0,0.5);

        --list-border: #3e4042;

        --ladder-line: #b0b3b8;
        --ladder-text: #e4e6eb;
    }
}

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

body {
    font-family: 'Apple SD Gothic Neo', 'Malgun Gothic', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    min-height: 100vh;
}

#app {
    width: 100%;
    max-width: 800px;
    background: var(--app-bg);
    padding: 20px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.hidden {
    display: none !important;
}

.screen {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    gap: 20px;
}

.active {
    display: flex;
}

h1, h2 {
    margin-bottom: 20px;
    color: var(--heading-color);
}

/* Controls */
.control-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.number-control {
    display: flex;
    align-items: center;
    gap: 10px;
}

.number-control input {
    width: 60px;
    text-align: center;
    font-size: 1.5rem;
    padding: 5px;
    border: 1px solid var(--border-color);
    background-color: var(--input-bg);
    color: var(--text-primary);
    border-radius: 4px;
}

button {
    cursor: pointer;
    border: 1px solid transparent;
    border-radius: 4px;
    padding: 10px 20px;
    font-size: 1rem;
    transition: background 0.2s, opacity 0.2s;
}

button:active {
    opacity: 0.8;
}

.primary-btn {
    background-color: var(--btn-primary-bg);
    color: var(--btn-primary-text);
    margin-top: 20px;
    width: 100%;
    max-width: 200px;
}

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

.secondary-btn {
    background-color: var(--btn-secondary-bg);
    color: var(--btn-secondary-text);
}

.secondary-btn:hover {
    background-color: var(--btn-secondary-hover);
}

/* Inputs Container */
.inputs-container {
    display: flex;
    width: 100%;
    gap: 20px;
    justify-content: space-around;
    overflow-y: auto;
    max-height: 60vh;
    padding: 10px;
}

.column {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.column h3 {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    position: sticky;
    top: 0;
    background: var(--app-bg);
    padding: 10px 0;
    z-index: 10;
}

.input-wrapper {
    display: flex;
    align-items: center;
    gap: 10px;
}

.input-label {
    min-width: 25px;
    text-align: center;
    font-weight: bold;
    color: var(--text-primary);
    background-color: var(--bg-color);
    padding: 5px;
    border-radius: 50%;
    border: 1px solid var(--border-color);
    font-size: 0.9rem;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 25px;
}

.column input {
    padding: 10px;
    border: 1px solid var(--input-border);
    background-color: var(--input-bg);
    color: var(--text-primary);
    border-radius: 4px;
    width: 100%;
    font-size: 1rem;
}

.button-group {
    display: flex;
    gap: 10px;
    margin-top: 20px;
    width: 100%;
    justify-content: center;
}

.button-group button {
    flex: 1;
    margin-top: 0;
    max-width: 200px;
}

/* Game Controls */
.game-controls {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    justify-content: center;
}

.game-controls button {
    background: var(--app-bg);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 8px 15px;
    font-size: 0.9rem;
}

.game-controls button:hover {
    background: var(--bg-color); /* slightly darker than app bg in light, lighter in dark? */
}

/* Canvas Container */
#canvas-container {
    width: 100%;
    flex: 1;
    position: relative;
    border: 1px solid var(--canvas-border);
    background: var(--canvas-bg);
    margin-top: 20px;
    min-height: 400px;
    overflow: hidden;
}

canvas {
    display: block;
    cursor: pointer;
}

/* Result Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--modal-overlay);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    background: var(--modal-bg);
    padding: 30px;
    border-radius: 8px;
    min-width: 300px;
    max-width: 90%;
    text-align: center;
    box-shadow: 0 4px 15px var(--modal-shadow);
}

#result-list {
    list-style: none;
    margin: 20px 0;
    text-align: left;
    max-height: 50vh;
    overflow-y: auto;
    border: 1px solid var(--list-border);
    border-radius: 4px;
}

#result-list li {
    padding: 12px;
    border-bottom: 1px solid var(--list-border);
    font-size: 1.1rem;
    color: var(--text-primary);
}

#result-list li:last-child {
    border-bottom: none;
}

#btn-close-result {
    background-color: var(--btn-secondary-bg);
    color: var(--btn-secondary-text);
    width: 100%;
    max-width: 150px;
}

/* Mobile Responsive */
@media (max-width: 600px) {
    #app {
        padding: 10px;
    }

    .inputs-container {
        flex-direction: row; /* Keep side by side for comparison, but tight */
        gap: 10px;
    }

    .column input {
        font-size: 0.9rem;
        padding: 8px;
    }

    h1 { font-size: 1.5rem; }
    h2 { font-size: 1.2rem; }

    .game-controls button {
        padding: 6px 10px;
        font-size: 0.8rem;
    }
}