.rails-board {
    width: min(92vw, 600px);
    display: grid;
    gap: 0 !important;
    padding: 0 !important;
    position: relative;
    overflow: hidden;
    user-select: none;
}

.rails-cell {
    width: 100%;
    aspect-ratio: 1;
    padding: 0;
    line-height: 1;
    border-radius: 0;
    border: none;
    box-shadow: inset -1px 0 0 0 var(--color-border-main),
                inset 0 -1px 0 0 var(--color-border-main);
    background: var(--color-bg-card);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-main);
    font-weight: 700;
    transition: all 120ms ease;
}

.rails-cell:hover {
    background: color-mix(in srgb, var(--color-selected-bg) 45%, var(--color-bg-card));
}

.rails-cell.is-fixed {
    background: color-mix(in srgb, #64748b 25%, var(--color-bg-card));
    font-weight: 700;
}

.rails-cell.is-track.is-initial-fixed {
    background: color-mix(in srgb, #64748b 18%, var(--color-bg-card));
    color: #334155;
    font-weight: 700;
}

.rails-cell.is-track {
    background: color-mix(in srgb, #94a3b8 12%, var(--color-bg-card));
    color: #475569;
}

.rails-cell.is-cross {
    background: var(--color-bg-card);
    color: var(--color-text-muted);
}

.rails-target {
    aspect-ratio: 1;
    line-height: 1;
    border-radius: 0;
    border: none;
    background: transparent;
    color: #64748b;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    font-weight: 600;
    margin: 2px;
}

.rails-track-svg {
    width: 100%;
    height: 100%;
    display: block;
}

.rails-cell.is-first-row {
    box-shadow: inset -1px 0 0 0 var(--color-border-main),
                inset 0 -1px 0 0 var(--color-border-main),
                inset 0 1px 0 0 var(--color-border-main);
}

.rails-cell.is-hint {
    box-shadow: inset 0 0 0 2px #94a3b8,
                inset -1px 0 0 0 var(--color-border-main),
                inset 0 -1px 0 0 var(--color-border-main);
    animation: rails-hint-pulse 1.2s ease;
}

.rails-hint-card {
    border: 1px solid #cbd5e1;
    background: #f8fafc;
    color: #334155;
    border-radius: 10px;
    padding: 0.6rem 0.7rem;
    font-size: 0.83rem;
    line-height: 1.25;
}

.rails-hint-title {
    font-weight: 700;
    margin-bottom: 0.2rem;
}

@keyframes rails-hint-pulse {
    0% {
        box-shadow: inset 0 0 0 3px color-mix(in srgb, var(--color-warning) 70%, transparent),
                    inset -1px 0 0 0 var(--color-border-main),
                    inset 0 -1px 0 0 var(--color-border-main);
    }
    100% {
        box-shadow: inset 0 0 0 2px var(--color-warning),
                    inset -1px 0 0 0 var(--color-border-main),
                    inset 0 -1px 0 0 var(--color-border-main);
    }
}

.rails-track-line {
    fill: none;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.rails-track-line-base {
    stroke: color-mix(in srgb, #475569 84%, var(--color-text-main) 16%);
    stroke-width: 20;
}

.rails-track-line-highlight {
    stroke: color-mix(in srgb, #94a3b8 58%, white 42%);
    stroke-width: 10;
}

.rails-track-hub {
    fill: color-mix(in srgb, #64748b 72%, var(--color-text-main) 28%);
}

.rails-target {
    color: var(--color-text-main);
    font-weight: 600;
    border-radius: 6px;
    transition: all 200ms ease;
}

.rails-target.is-ok {
    color: var(--color-success-text);
    font-weight: 800;
    background: var(--color-accent-green);
    box-shadow: 0 0 0 2px var(--color-emerald-300);
}

.rails-target.is-error {
    color: white;
    font-weight: 800;
    background: var(--color-error);
    box-shadow: 0 0 0 2px var(--color-error-light);
}

.rails-board[data-size="6"] .rails-cell,
.rails-board[data-size="6"] .rails-target {
    font-size: 1rem;
}

.rails-board[data-size="8"] {
    max-width: min(92vw, 34rem);
}

.rails-board[data-size="8"] .rails-cell,
.rails-board[data-size="8"] .rails-target {
    font-size: 0.86rem;
}

.rails-board[data-size="8"] .rails-cell i {
    width: 0.8rem;
    height: 0.8rem;
}

.rails-tool-btn {
    border: 1px solid var(--color-border-main);
    background: var(--color-bg-card);
    border-radius: 12px;
    min-height: 42px;
    color: var(--color-text-main);
    font-weight: 700;
    font-size: 13px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    transition: all 120ms ease;
}

.rails-tool-btn:hover {
    border-color: #94a3b8;
    background: #f1f5f9;
}

.rails-tool-btn.is-active {
    border-color: #64748b;
    color: #334155;
    background: #e2e8f0;
}

@media (max-width: 640px) {
    .rails-board {
        width: 100%;
        max-width: 96vw;
        gap: 0 !important;
    }

    .rails-board[data-size="8"] {
        max-width: 96vw;
    }

    .rails-target {
        font-size: 0.92rem;
    }

    .rails-board[data-size="8"] .rails-cell,
    .rails-board[data-size="8"] .rails-target {
        font-size: 0.78rem;
    }

    .rails-board[data-size="8"] .rails-cell i {
        width: 0.72rem;
        height: 0.72rem;
    }
}