/* ===== 基础 ===== */
:root {
    --accent: #2563eb;
    --accent-dark: #1d4ed8;
    --ink: #2b3445;
    --line: #e3e8f0;
    --danger: #d32f2f;
    --safe: #2e9e4f;
    --warn: #c47a00;

    --wall: #2B2B2B;        /* 边界与交点 */
    --wall-placed: #3F6FD8; /* 放置的墙 */
    --wall-empty: #FFFFFF;  /* 无墙 */
    --grid: #E4E4E4;        /* 格子底色 */
    --start: #D6E7FF;       /* 起点 */
    --goal: #FFD9D9;        /* 终点 */
    --cell-black: #595959;  /* 奇数通路 */
    --cell-white: #FFFFFF;  /* 偶数通路 */

    --cell-size: 56px;
    --wall-size: 10px;
    --num-font: 13px;
}
* { box-sizing: border-box; }
body {
    margin: 0;
    padding: 12px;
    background: #eef2f7;
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    color: var(--ink);
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
}
.container {
    position: relative;
    max-width: 720px;
    margin: auto;
    background: #fff;
    border-radius: 14px;
    box-shadow: 0 6px 24px rgba(20, 40, 80, 0.10);
    padding: 20px 22px 16px;
}
.back-home {
    position: absolute;
    left: 14px;
    top: 14px;
    z-index: 2;
    padding: 6px 12px;
    background: #f1f5fb;
    color: var(--accent);
    border: 1px solid var(--line);
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
    text-decoration: none;
    transition: all .15s;
}
.back-home:hover {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
}
h1 {
    text-align: center;
    margin: 0 0 16px;
    font-size: 22px;
    letter-spacing: .5px;
}

/* ===== 控件 ===== */
.controls {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 8px 18px;
    margin-bottom: 10px;
}
/* 同一组控件整体换行 */
.control-group {
    display: flex;
    align-items: center;
    gap: 12px;
}
.controls label {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    color: #55617a;
}
.controls input[type="number"] {
    width: 56px;
    padding: 6px 8px;
    border: 1px solid #ccd4e0;
    border-radius: 6px;
    font-size: 14px;
    text-align: center;
}
.controls input[type="number"]:focus { outline: 2px solid var(--accent); border-color: transparent; }
.controls input[type="number"]::placeholder { font-size: 12px; color: #aab3c0; }

/* 黑白模式开关 */
.switch { cursor: pointer; user-select: none; }
.switch input { position: absolute; opacity: 0; width: 0; height: 0; }
.switch-track {
    position: relative;
    width: 38px;
    height: 20px;
    border-radius: 10px;
    background: #ccd4e0;
    transition: background .15s;
    flex: none;
}
.switch-dot {
    position: absolute;
    top: 2px;
    left: 2px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: #fff;
    box-shadow: 0 1px 3px rgba(0, 0, 0, .25);
    transition: transform .15s;
}
.switch input:checked + .switch-track { background: var(--cell-black); }
.switch input:checked + .switch-track .switch-dot { transform: translateX(18px); }
.switch input:focus-visible + .switch-track { outline: 2px solid var(--accent); outline-offset: 2px; }

button.primary, button.ghost {
    padding: 7px 16px;
    border-radius: 8px;
    font-size: 14px;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all .15s;
}
button.primary { background: var(--accent); color: #fff; }
button.primary:hover { background: var(--accent-dark); }
button.primary.done { background: var(--safe); }
button.ghost { background: #fff; color: #55617a; border-color: #ccd4e0; }
button.ghost:hover { background: #f3f6fb; }

/* ===== 状态提示 ===== */
.status {
    text-align: center;
    min-height: 22px;
    margin: 4px 0 8px;
    font-size: 14px;
    color: #55617a;
}
.status b { color: var(--ink); }
.status .ok { color: var(--safe); }
.status .warn { color: var(--warn); }
.status .hint { color: #9098a8; }
.status .error { color: var(--danger); font-weight: 600; }
.status .count { white-space: nowrap; }
.status .note { margin-left: 12px; }

/* ===== 迷宫 ===== */
.maze-wrap {
    display: flex;
    justify-content: safe center;
    overflow-x: auto;
    padding: 2px 0;
}
.maze {
    display: grid;
    flex: none;
    touch-action: manipulation;
}

/* 交点与地图边界 */
.corner, .border { background: var(--wall); }

/* 墙壁位置 */
.slot {
    background: var(--wall-empty);
    position: relative;
    cursor: pointer;
    z-index: 2;
    transition: background .1s;
}
.slot.on { background: var(--wall-placed); }
.slot:hover { background: #bdcef1; }
.slot.on:hover { background: #6f92e3; }
/* 扩大触摸热区：横墙向上下、纵墙向左右各延伸格子的两成 */
.slot::after {
    content: '';
    position: absolute;
    inset: calc(var(--cell-size) * -0.2) 0;
}
.slot.vertical::after { inset: 0 calc(var(--cell-size) * -0.2); }

/* 格子 */
.cell {
    position: relative;
    background: var(--grid);
    z-index: 1;
}
.cell .num {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
    padding: 1px 3px;
    font-size: var(--num-font);
    line-height: 1;
    color: #6E6E6E;
    background: #EFEFEF;
    border-bottom-right-radius: 4px;
    user-select: none;
}
/* 地标：起点与终点 */
.cell .mark {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
    font-size: calc(var(--cell-size) * 0.43);
    font-weight: bold;
    user-select: none;
}
.cell.start { background: var(--start); }
.cell.goal { background: var(--goal); }

/* 黑白信息方块：边长为格子的 42 / 56 */
.cell .square {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: calc(var(--cell-size) * 0.75);
    height: calc(var(--cell-size) * 0.75);
    border: 1px solid #8C8C8C;
    background: var(--cell-white);
    display: none;
}
.cell .square.black { background: var(--cell-black); }
/* 起点与终点不展示黑白信息 */
.maze.bw .cell:not(.start):not(.goal) .square { display: block; }

/* ===== 图例 ===== */
.legend {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 6px 16px;
    margin: 10px 0 12px;
    font-size: 13px;
    color: #55617a;
}
.legend-item { display: inline-flex; align-items: center; gap: 5px; }
.legend .bw-only { display: none; }
.legend.bw .bw-only { display: inline-flex; }
.swatch {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 1px solid #999999;
    flex: none;
}
.swatch.cell-start { background: var(--start); }
.swatch.cell-goal { background: var(--goal); }
.swatch.wall-on { background: var(--wall-placed); }
.swatch.wall-off { background: var(--wall-empty); }
.swatch.cell-black { background: var(--cell-black); }
.swatch.cell-white { background: var(--cell-white); }

/* ===== 指令输出 ===== */
.command {
    border-top: 1px solid var(--line);
    padding-top: 12px;
}
.command-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    margin-bottom: 8px;
}
.command-label { font-size: 14px; font-weight: 600; color: #55617a; }
.command-box {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #ccd4e0;
    border-radius: 8px;
    background: #f8fafd;
    font-family: 'Consolas', 'Courier New', monospace;
    font-size: 14px;
    line-height: 1.6;
    color: var(--ink);
    resize: vertical;
}
.command-box:focus { outline: 2px solid var(--accent); border-color: transparent; }

/* ===== 帮助 ===== */
.help {
    margin-top: 14px;
    border-top: 1px solid var(--line);
    padding-top: 10px;
    font-size: 13px;
    color: #55617a;
}
.help summary {
    cursor: pointer;
    font-weight: 600;
    color: var(--accent);
    user-select: none;
}
.help-body { margin-top: 8px; line-height: 1.7; }
.help-body p { margin: 6px 0; }

@media (max-width: 480px) {
    .container { padding: 52px 12px 12px; }
    h1 { font-size: 19px; margin-bottom: 12px; }
    .back-home { left: 12px; top: 12px; }

    /* 固定两列：四个数字输入框占第一行，开关与按钮占第二行 */
    .controls {
        display: grid;
        grid-template-columns: repeat(2, auto);
        justify-content: center;
        gap: 8px 16px;
    }
    .control-group { gap: 8px; }
    .control-group:last-child { grid-column: 1 / -1; justify-content: center; }
    .controls label { font-size: 13px; gap: 5px; }
    /* 字号不小于 16px */
    .controls input[type="number"] { width: 42px; padding: 5px 4px; font-size: 16px; }

    /* 墙数与结论各占一行，不再从句子中间折行 */
    .status { font-size: 13px; }
    .status .count, .status .note { display: block; }
    .status .note { margin: 2px 0 0; }
    .legend { gap: 4px 12px; margin: 8px 0 10px; font-size: 12px; }
    .command-box { font-size: 13px; }
    .help { font-size: 12px; }
}