:root {
    --mini4-bg: #fffdf0;
    --mini4-paper: #fcfcfc;
    --mini4-panel: #f4efe0;
    --mini4-ink: #151415;
    --mini4-accent: #3972e1;
    --mini4-accent-soft: #d8e9ff;
    --mini4-success: #6fcd78;
    --mini4-warning: #ffcc66;
    --mini4-danger: #ff8e8e;
    --mini4-shadow: 6px 6px 0 #151415;
    --mini4-radius: 20px;
    --mini4-gap: 16px;
}

body.sudoku4x4-page {
    background: var(--mini4-bg);
    color: var(--mini4-ink);
}

.sudoku4x4-shell {
    width: min(1200px, calc(100% - 32px));
    margin: 0 auto;
    padding: 32px 0 56px;
}

.sudoku4x4-hero {
    display: grid;
    grid-template-columns: minmax(0, 1.1fr) minmax(280px, 0.9fr);
    gap: 24px;
    align-items: stretch;
    margin-bottom: 28px;
}

.sudoku4x4-card {
    background: var(--mini4-paper);
    border: 4px solid var(--mini4-ink);
    border-radius: var(--mini4-radius);
    box-shadow: var(--mini4-shadow);
}

.sudoku4x4-intro,
.sudoku4x4-sidecard {
    padding: 24px;
}

.sudoku4x4-eyebrow {
    display: inline-flex;
    margin: 0 0 14px;
    padding: 6px 12px;
    border: 3px solid var(--mini4-ink);
    border-radius: 999px;
    background: #ffef99;
    font-size: 0.9rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.sudoku4x4-title {
    margin: 0 0 12px;
    font-size: clamp(2rem, 4vw, 3.4rem);
    line-height: 1;
}

.sudoku4x4-lead {
    margin: 0 0 16px;
    font-size: 1.05rem;
    line-height: 1.6;
    max-width: 58ch;
}

.sudoku4x4-feature-list,
.sudoku4x4-tip-list {
    margin: 0;
    padding-left: 20px;
    line-height: 1.7;
}

.sudoku4x4-tip-list li + li,
.sudoku4x4-feature-list li + li {
    margin-top: 8px;
}

.sudoku4x4-sidecard h2,
.sudoku4x4-section h2 {
    margin: 0 0 12px;
    font-size: 1.45rem;
}

.sudoku4x4-sidecard p,
.sudoku4x4-section p {
    margin: 0 0 14px;
    line-height: 1.6;
}

.sudoku4x4-layout {
    display: grid;
    grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
    gap: 28px;
    align-items: start;
}

.sudoku4x4-game {
    padding: 24px;
}

.sudoku4x4-toolbar {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
    margin-bottom: 18px;
}

.sudoku4x4-field {
    display: grid;
    gap: 8px;
}

.sudoku4x4-field label {
    font-weight: 700;
}

.sudoku4x4-select {
    width: 100%;
    min-height: 46px;
    padding: 10px 12px;
    border: 3px solid var(--mini4-ink);
    border-radius: 14px;
    background: #fff;
    color: var(--mini4-ink);
    font: inherit;
    font-weight: 700;
}

.sudoku4x4-status {
    display: none;
}

.sudoku4x4-status[data-tone="success"] {
    background: #dff8df;
}

.sudoku4x4-status[data-tone="warning"] {
    background: #fff0bf;
}

.sudoku4x4-status[data-tone="info"] {
    background: var(--mini4-accent-soft);
}

.sudoku4x4-board-wrap {
    display: flex;
    justify-content: center;
    margin-bottom: 18px;
}

.sudoku4x4-board {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 78px));
    gap: 0;
    border: 4px solid var(--mini4-ink);
    border-radius: 22px;
    overflow: hidden;
    background: var(--mini4-paper);
    box-shadow: var(--mini4-shadow);
}

.sudoku4x4__cell {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 78px;
    padding: 10px;
    border: 0;
    border-right: 3px solid var(--mini4-ink);
    border-bottom: 3px solid var(--mini4-ink);
    background: #fff;
    color: var(--mini4-ink);
    cursor: pointer;
    transition: transform 0.12s ease, background-color 0.12s ease;
}

.sudoku4x4__cell:nth-child(4n) {
    border-right: 0;
}

.sudoku4x4__cell:nth-last-child(-n + 4) {
    border-bottom: 0;
}

.sudoku4x4__cell:nth-child(n + 5):nth-child(-n + 8) {
    border-bottom-width: 4px;
}

.sudoku4x4__cell:nth-child(4n + 2) {
    border-right-width: 4px;
}

.sudoku4x4__cell:hover {
    transform: translate(-1px, -1px);
}

.sudoku4x4__cell.is-selected {
    background: #c6dafc;
}

.sudoku4x4__cell.is-highlighted {
    background: #fff0bf;
    background-image: none;
}

.sudoku4x4__cell.is-target {
    background: #ffd43b;
    background-image: none;
    box-shadow: inset 0 0 0 3px var(--mini4-ink);
}

.sudoku4x4__cell.is-given:not(.is-highlighted):not(.is-target) {
    background: #eff3fc;
}

.sudoku4x4__cell.is-empty:not(.is-highlighted):not(.is-target) {
    background-image: linear-gradient(135deg, rgba(21, 20, 21, 0.05), rgba(21, 20, 21, 0));
}

.sudoku4x4__cell-content {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-height: 42px;
    font-size: 2rem;
    font-weight: 800;
    line-height: 1;
}

.sudoku4x4__cell-content[data-render-mode="image"] {
    min-height: 56px;
}

.sudoku4x4__cell-image {
    display: block;
    width: 52px;
    height: 52px;
    object-fit: contain;
}

.sudoku4x4__cell-placeholder {
    display: inline-block;
    width: 1.2rem;
    min-height: 1.2rem;
}

.sudoku4x4-actions,
.sudoku4x4-palette {
    display: grid;
    gap: 10px;
}

.sudoku4x4-actions {
    grid-template-columns: repeat(5, minmax(0, 1fr));
}

.sudoku4x4-actions {
    margin-bottom: 16px;
}

.sudoku4x4-palette {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    margin-bottom: 18px;
}

.sudoku4x4__palette-symbol {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-height: 36px;
    line-height: 1;
}

.sudoku4x4__palette-symbol img {
    display: block;
    width: 36px;
    height: 36px;
    margin: 0 auto;
    object-fit: contain;
}

.sudoku4x4-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 46px;
    padding: 10px 12px;
    border: 3px solid var(--mini4-ink);
    border-radius: 14px;
    background: #fff;
    color: var(--mini4-ink);
    font: inherit;
    font-weight: 800;
    cursor: pointer;
    box-shadow: 3px 3px 0 var(--mini4-ink);
    transition: transform 0.12s ease, box-shadow 0.12s ease, background-color 0.12s ease;
}

.sudoku4x4-button--icon {
    padding: 6px;
}

.sudoku4x4__erase-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
}

.sudoku4x4__erase-icon svg {
    display: block;
    width: 24px;
    height: 24px;
}

.sudoku4x4-button:hover:not(:disabled) {
    transform: translate(-1px, -1px);
    box-shadow: 4px 4px 0 var(--mini4-ink);
}

.sudoku4x4-button:disabled {
    opacity: 0.45;
    cursor: not-allowed;
    box-shadow: none;
}

.sudoku4x4-button--primary {
    background: #a8d8ff;
}

.sudoku4x4-button--accent {
    background: #ffe28a;
}

.sudoku4x4-button--success {
    background: #cdf0d0;
}

.sudoku4x4-hint {
    padding: 18px;
    border: 3px dashed var(--mini4-ink);
    border-radius: 18px;
    background: #fffef8;
}

.sudoku4x4-hint h2 {
    margin: 0 0 10px;
    font-size: 1.2rem;
}

.sudoku4x4-hint p {
    margin: 0;
    line-height: 1.6;
}

.sudoku4x4-sidebar {
    display: grid;
    gap: 20px;
}

.sudoku4x4-section {
    padding: 24px;
}

.sudoku4x4-section a {
    color: var(--mini4-accent);
    font-weight: 700;
}

@media (max-width: 960px) {
    .sudoku4x4-hero,
    .sudoku4x4-layout {
        grid-template-columns: 1fr;
    }

    .sudoku4x4-sidecard {
        order: -1;
    }
}

@media (max-width: 680px) {
    .sudoku4x4-shell {
        width: min(100% - 20px, 1200px);
        padding-top: 20px;
    }

    .sudoku4x4-intro,
    .sudoku4x4-sidecard,
    .sudoku4x4-game,
    .sudoku4x4-section {
        padding: 18px;
    }

    .sudoku4x4-toolbar {
        grid-template-columns: 1fr;
    }

    .sudoku4x4-board {
        grid-template-columns: repeat(4, minmax(0, 68px));
    }

    .sudoku4x4__cell {
        min-height: 68px;
    }

    .sudoku4x4-actions {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .sudoku4x4-palette {
        grid-template-columns: repeat(5, minmax(0, 1fr));
    }

    .sudoku4x4-button {
        min-height: 44px;
        padding: 9px 10px;
    }
}

@media (max-width: 480px) {
    .sudoku4x4-title {
        font-size: 1.9rem;
    }

    .sudoku4x4-board {
        width: 100%;
        grid-template-columns: repeat(4, minmax(0, 1fr));
    }

    .sudoku4x4__cell {
        min-height: 58px;
        padding: 8px;
    }

    .sudoku4x4__cell-content {
        font-size: 1.7rem;
    }

    .sudoku4x4__cell-image {
        width: 40px;
        height: 40px;
    }

    .sudoku4x4-actions,
    .sudoku4x4-palette {
        gap: 8px;
    }

    .sudoku4x4-button {
        min-height: 40px;
        padding: 8px 10px;
        border-radius: 12px;
    }

    .sudoku4x4__palette-symbol img {
        width: 24px;
        height: 24px;
    }
}