:root {
    --sudoku-bg: radial-gradient(circle at top left, #1e1e2f, #12121c);
    --sudoku-surface: rgba(18, 18, 28, 0.92);
    --sudoku-surface-light: rgba(255, 255, 255, 0.08);
    --sudoku-border: rgba(255, 255, 255, 0.08);
    --sudoku-accent: #4ecdc4;
    --sudoku-accent-strong: #38a3a5;
    --sudoku-warning: #ff6b6b;
    --sudoku-success: #8fd694;
    --sudoku-text: #f1f5ff;
    --sudoku-text-muted: #9ea4c6;
    --sudoku-grid-line: rgba(255, 255, 255, 0.15);
    --sudoku-grid-block-line: rgba(255, 255, 255, 0.35);
    --sudoku-highlight: rgba(78, 205, 196, 0.12);
    --sudoku-conflict: rgba(255, 107, 107, 0.25);
    --sudoku-font-scale: 1;
}

body.sudoku-theme {
    margin: 0;
    min-height: 100vh;
    background: var(--sudoku-bg);
    color: var(--sudoku-text);
    font-family: 'Poppins', 'Segoe UI', system-ui, -apple-system, sans-serif;
    display: flex;
    justify-content: center;
}

body[data-sudoku-theme="light"] {
    --sudoku-bg: linear-gradient(120deg, #f8fbff, #ecf3ff);
    --sudoku-surface: rgba(255, 255, 255, 0.85);
    --sudoku-surface-light: rgba(0, 0, 0, 0.04);
    --sudoku-border: rgba(0, 0, 0, 0.08);
    --sudoku-accent: #3a7bd5;
    --sudoku-accent-strong: #2764bb;
    --sudoku-warning: #d64550;
    --sudoku-success: #4caf50;
    --sudoku-text: #111727;
    --sudoku-text-muted: #4e5671;
    --sudoku-grid-line: rgba(0, 0, 0, 0.12);
    --sudoku-grid-block-line: rgba(0, 0, 0, 0.45);
    --sudoku-highlight: rgba(58, 123, 213, 0.12);
    --sudoku-conflict: rgba(214, 69, 80, 0.2);
}

body[data-sudoku-theme="dark"] {
    --sudoku-bg: radial-gradient(circle at 20% 20%, #16162b, #090913);
    --sudoku-surface: rgba(12, 12, 20, 0.95);
}

body[data-font-size="compact"] {
    --sudoku-font-scale: 0.9;
}

body[data-font-size="large"] {
    --sudoku-font-scale: 1.1;
}

#sudoku-app {
    width: 100%;
}

.sudoku-game-screen {
    display: none;
    min-height: 100vh;
    padding: 80px 24px;
}

.sudoku-game-screen.active,
.game-menu-screen.active {
    display: block;
}

.sudoku-layout {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 270px minmax(0, 1fr) 270px;
    gap: 24px;
}

.sudoku-sidebar {
    background: var(--sudoku-surface);
    border-radius: 24px;
    padding: 24px;
    border: 1px solid var(--sudoku-border);
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.sudoku-status-cards {
    display: grid;
    gap: 16px;
}

.status-card {
    background: var(--sudoku-surface-light);
    border-radius: 20px;
    padding: 16px;
    border: 1px solid var(--sudoku-border);
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.status-label {
    font-size: 0.85rem;
    color: var(--sudoku-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.6px;
}

.status-value {
    font-size: calc(1.4rem * var(--sudoku-font-scale));
    font-weight: 700;
}

.timer-value {
    font-variant-numeric: tabular-nums;
}

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

.progress-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--sudoku-text-muted);
    font-size: 0.95rem;
}

.progress-bar {
    height: 8px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 999px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(135deg, var(--sudoku-accent), var(--sudoku-accent-strong));
    border-radius: 999px;
    transition: width 0.3s ease;
}

.tool-buttons {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.tool-btn {
    background: var(--sudoku-surface-light);
    border: 1px solid var(--sudoku-border);
    border-radius: 12px;
    padding: 10px 14px;
    color: var(--sudoku-text);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    justify-content: center;
    transition: transform 0.2s ease, border-color 0.2s ease;
}

.tool-btn:hover {
    transform: translateY(-2px);
    border-color: rgba(78, 205, 196, 0.45);
}

.tool-btn.toggle-btn.active {
    background: rgba(78, 205, 196, 0.18);
    border-color: rgba(78, 205, 196, 0.45);
    color: var(--sudoku-accent);
}

.undo-redo {
    display: flex;
    gap: 10px;
}

.undo-redo .tool-btn {
    flex: 1;
}

.sudoku-board-wrapper {
    background: var(--sudoku-surface);
    border-radius: 32px;
    padding: 26px;
    border: 1px solid var(--sudoku-border);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.25);
    position: relative;
}

.sudoku-board {
    display: grid;
    grid-template-rows: repeat(9, minmax(0, 1fr));
    grid-template-columns: repeat(9, minmax(0, 1fr));
    width: min(70vh, 560px);
    aspect-ratio: 1 / 1;
    border: 2px solid var(--sudoku-grid-block-line);
    background: rgba(0, 0, 0, 0.15);
    border-radius: 16px;
    overflow: hidden;
}

.sudoku-board[data-size="4"] {
    grid-template-rows: repeat(4, minmax(0, 1fr));
    grid-template-columns: repeat(4, minmax(0, 1fr));
    width: min(60vh, 360px);
    max-width: 360px;
}

.sudoku-board[data-size="4"] .sudoku-cell {
    font-size: calc(2.5rem * var(--sudoku-font-scale));
}

.sudoku-board-wrapper.paused .sudoku-board {
    filter: blur(1px);
    opacity: 0.45;
    pointer-events: none;
}

.sudoku-pause-overlay {
    position: absolute;
    inset: 0;
    background: rgba(10, 16, 28, 0.78);
    display: none;
    align-items: center;
    justify-content: center;
    border-radius: 32px;
    text-align: center;
    padding: 24px;
    gap: 16px;
    flex-direction: column;
    color: var(--sudoku-text);
    backdrop-filter: blur(4px);
    z-index: 5;
}

.sudoku-pause-overlay.active {
    display: flex;
}

.sudoku-pause-overlay .pause-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.sudoku-pause-overlay .pause-content i {
    font-size: 2.5rem;
    color: var(--sudoku-accent);
}

.sudoku-pause-overlay .pause-content p {
    font-size: 1.4rem;
    font-weight: 600;
    margin: 0;
}

.sudoku-pause-overlay .resume-btn {
    background: linear-gradient(135deg, var(--sudoku-accent), var(--sudoku-accent-strong));
    color: #ffffff;
    border: none;
    padding: 0.65rem 1.6rem;
    border-radius: 999px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.25);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.sudoku-pause-overlay .resume-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 16px 40px rgba(0, 0, 0, 0.3);
}

.sudoku-pause-overlay .resume-btn i {
    font-size: 1rem;
    color: inherit;
}

.sudoku-row {
    display: contents;
}

.sudoku-cell {
    border: 1px solid var(--sudoku-grid-line);
    font-size: calc(2.2rem * var(--sudoku-font-scale));
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    font-weight: 600;
    transition: background 0.12s ease, color 0.12s ease, box-shadow 0.12s ease;
    cursor: pointer;
    outline: none;
    color: var(--sudoku-text);
    background: rgba(0, 0, 0, 0.15);
}

.sudoku-cell.given {
    font-weight: 700;
    background: rgba(78, 205, 196, 0.1);
}

.sudoku-cell.selected {
    background: rgba(78, 205, 196, 0.22);
    box-shadow: inset 0 0 0 2px rgba(78, 205, 196, 0.65);
}

.sudoku-cell.match {
    background: rgba(255, 214, 102, 0.12);
    box-shadow: inset 0 0 0 1px rgba(255, 214, 102, 0.4);
}

.sudoku-cell.selected.match {
    background: rgba(78, 205, 196, 0.22);
    box-shadow: inset 0 0 0 2px rgba(78, 205, 196, 0.65);
}

.sudoku-cell.conflict {
    animation: cellConflict 0.5s ease;
    background: var(--sudoku-conflict);
}

.block-border-right {
    border-right: 2px solid var(--sudoku-grid-block-line);
}

.block-border-bottom {
    border-bottom: 2px solid var(--sudoku-grid-block-line);
}

.pencil-marks {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    gap: 2px;
    font-size: calc(0.75rem * var(--sudoku-font-scale));
    width: 90%;
    height: 90%;
    justify-items: center;
    align-items: center;
    color: var(--sudoku-text-muted);
}

.pencil-marks span {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
}

.pencil-marks span.match {
    color: #362203;
    font-weight: 600;
    background: rgba(255, 214, 102, 0.12);
    border-radius: 4px;
}

.number-pad {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
}

.number-pad button {
    height: 56px;
    border-radius: 16px;
    border: 1px solid var(--sudoku-border);
    background: var(--sudoku-surface-light);
    color: var(--sudoku-text);
    font-size: calc(1.35rem * var(--sudoku-font-scale));
    font-weight: 700;
    cursor: pointer;
    transition: transform 0.15s ease, border-color 0.15s ease;
}

.number-pad button:hover {
    transform: translateY(-2px);
    border-color: rgba(78, 205, 196, 0.45);
}

.number-pad button.active {
    background: rgba(78, 205, 196, 0.2);
    border-color: rgba(78, 205, 196, 0.6);
    color: var(--sudoku-accent);
}

.number-pad button.depleted {
    opacity: 0.4;
    pointer-events: none;
    filter: grayscale(0.4);
}

.number-pad button:disabled {
    cursor: not-allowed;
}

.number-pad button.wide {
    grid-column: span 3;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.sudoku-toggles {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.toggle-row {
    position: relative;
    padding: 14px 16px;
    border-radius: 14px;
    border: 1px solid var(--sudoku-border);
    background: var(--sudoku-surface-light);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    font-size: 0.95rem;
}

.toggle-row input {
    position: absolute;
    height: 0;
    width: 0;
    opacity: 0;
}

.toggle-switch {
    width: 44px;
    height: 24px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.12);
    position: relative;
    flex: 0 0 auto;
    transition: background 0.2s ease;
}

.toggle-switch::after {
    content: "";
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--sudoku-text);
    position: absolute;
    top: 2px;
    left: 2px;
    transition: transform 0.2s ease;
}

.toggle-row input:checked + .toggle-switch {
    background: rgba(78, 205, 196, 0.35);
}

.toggle-row input:checked + .toggle-switch::after {
    transform: translateX(20px);
    background: var(--sudoku-accent);
}

.sudoku-settings.quick .settings-row {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.sudoku-settings.quick label {
    font-size: 0.95rem;
    color: var(--sudoku-text-muted);
}

.sudoku-settings.quick select {
    padding: 10px;
    border-radius: 12px;
    border: 1px solid var(--sudoku-border);
    background: var(--sudoku-surface-light);
    color: var(--sudoku-text);
}

.modal {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.92);
    opacity: 0;
    visibility: hidden;
    background: var(--sudoku-surface);
    border-radius: 24px;
    border: 1px solid var(--sudoku-border);
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.25);
    padding: 24px;
    max-width: 800px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    transition: opacity 0.2s ease, transform 0.2s ease;
    z-index: 200;
}

.modal.active {
    opacity: 1;
    visibility: visible;
    transform: translate(-50%, -50%) scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
}

.modal-header h2 {
    margin: 0;
    font-size: 1.6rem;
}

.modal-close {
    background: transparent;
    border: none;
    color: var(--sudoku-text);
    font-size: 1.2rem;
    cursor: pointer;
}

.modal-body {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 18px;
}

.settings-section {
    background: var(--sudoku-surface-light);
    border-radius: 18px;
    border: 1px solid var(--sudoku-border);
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.settings-section h3 {
    margin: 0;
    font-size: 1.15rem;
}

.stats-overview {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 16px;
}

.stats-section {
    background: var(--sudoku-surface-light);
    padding: 18px;
    border-radius: 18px;
    border: 1px solid var(--sudoku-border);
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.stats-section h3 {
    margin: 0;
    font-size: 1.2rem;
}

.best-times {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
}

.best-time-card {
    background: rgba(0, 0, 0, 0.18);
    border-radius: 16px;
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.best-time-card .difficulty {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--sudoku-text-muted);
}

.best-time-card .time {
    font-size: 1.3rem;
    font-weight: 600;
}

.streak-calendar {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 8px;
}

.calendar-day {
    width: 100%;
    padding-top: 100%;
    position: relative;
    border-radius: 8px;
    background: rgba(78, 205, 196, 0.18);
    border: 1px solid rgba(78, 205, 196, 0.35);
}

.results-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.95rem;
}

.results-table th,
.results-table td {
    padding: 10px 12px;
    border-bottom: 1px solid var(--sudoku-border);
    text-align: left;
}

.results-table tbody tr:hover {
    background: rgba(78, 205, 196, 0.08);
}

.results-table .empty-state {
    text-align: center;
    color: var(--sudoku-text-muted);
}

.help-content {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.help-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 18px;
}

.help-section {
    background: var(--sudoku-surface-light);
    border-radius: 18px;
    border: 1px solid var(--sudoku-border);
    padding: 16px;
}

.help-section h3 {
    margin-top: 0;
}

.help-section ul {
    padding-left: 18px;
    margin: 10px 0 0;
}

.toast-container {
    position: fixed;
    bottom: 30px;
    right: 30px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    z-index: 300;
}

.toast {
    background: rgba(12, 12, 20, 0.9);
    color: var(--sudoku-text);
    padding: 14px 20px;
    border-radius: 12px;
    box-shadow: 0 14px 30px rgba(0, 0, 0, 0.25);
    opacity: 0;
    transform: translateY(12px);
    transition: opacity 0.2s ease, transform 0.2s ease;
    border: 1px solid rgba(255, 255, 255, 0.08);
    font-size: 0.95rem;
}

.toast.visible {
    opacity: 1;
    transform: translateY(0);
}

.toast-success {
    border-color: rgba(143, 214, 148, 0.45);
}

.toast-error {
    border-color: rgba(255, 107, 107, 0.45);
}

.results-overlay {
    position: fixed;
    inset: 0;
    background: rgba(6, 10, 22, 0.82);
    backdrop-filter: blur(12px);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 240;
    padding: 24px;
}

.results-overlay.active {
    display: flex;
}

.results-panel {
    position: relative;
    width: min(540px, 100%);
    background: linear-gradient(160deg, rgba(26, 32, 56, 0.96), rgba(13, 18, 34, 0.96));
    border-radius: 28px;
    border: 1px solid rgba(255, 255, 255, 0.08);
    box-shadow: 0 24px 80px rgba(0, 0, 0, 0.45);
    padding: 36px 32px 30px;
    color: var(--sudoku-text);
    overflow: hidden;
    animation: modalPop 0.3s ease;
}

@keyframes modalPop {
    from {
        transform: translateY(12px) scale(0.96);
        opacity: 0;
    }
    to {
        transform: translateY(0) scale(1);
        opacity: 1;
    }
}

.results-close {
    position: absolute;
    top: 16px;
    right: 16px;
    border: none;
    background: rgba(255, 255, 255, 0.06);
    color: var(--sudoku-text);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: grid;
    place-items: center;
    cursor: pointer;
    transition: background 0.2s ease, transform 0.2s ease;
    z-index: 2;
}

.results-close:hover {
    background: rgba(255, 255, 255, 0.12);
    transform: rotate(90deg);
}

.results-hero {
    text-align: center;
    margin-bottom: 24px;
    position: relative;
    z-index: 1;
}

.results-icon {
    width: 88px;
    height: 88px;
    border-radius: 50%;
    margin: 0 auto 14px;
    background: radial-gradient(circle at 30% 30%, rgba(78, 205, 196, 0.8), rgba(56, 163, 165, 0.6));
    box-shadow: 0 10px 28px rgba(78, 205, 196, 0.45);
    display: grid;
    place-items: center;
    font-size: 2.4rem;
    color: #061018;
}

.results-title {
    margin: 0;
    font-size: 2.2rem;
    letter-spacing: 0.6px;
}

.results-subtitle {
    margin: 8px 0 0;
    color: var(--sudoku-text-muted);
    font-size: 1rem;
}

.results-content {
    display: flex;
    flex-direction: column;
    gap: 18px;
}

.results-stats {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 12px;
}

.results-stat-card {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 18px;
    padding: 14px 12px;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.06);
    backdrop-filter: blur(4px);
}

.stat-label {
    display: block;
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--sudoku-text-muted);
    margin-bottom: 6px;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
}

.results-meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
    margin-top: 4px;
}

.meta-item {
    background: rgba(255, 255, 255, 0.04);
    border-radius: 16px;
    padding: 12px 14px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.meta-label {
    font-size: 0.8rem;
    color: var(--sudoku-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.8px;
}

.meta-value {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--sudoku-text);
}

.results-actions {
    display: flex;
    gap: 12px;
    margin-top: 26px;
}

.results-actions .btn {
    flex: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 16px;
    border-radius: 14px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    border: 1px solid transparent;
    transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.2s ease;
}

.results-actions .btn i {
    font-size: 1rem;
}

.results-actions .btn.primary {
    background: linear-gradient(140deg, #4ecdc4, #38a3a5);
    color: #041013;
    box-shadow: 0 12px 30px rgba(78, 205, 196, 0.35);
}

.results-actions .btn.primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 18px 32px rgba(78, 205, 196, 0.45);
}

.results-actions .btn.secondary {
    background: rgba(255, 255, 255, 0.08);
    color: var(--sudoku-text);
    border-color: rgba(255, 255, 255, 0.12);
}

.results-actions .btn.secondary:hover {
    background: rgba(255, 255, 255, 0.12);
}

.results-actions .btn.tertiary {
    background: transparent;
    color: var(--sudoku-text-muted);
    border-color: rgba(255, 255, 255, 0.08);
}

.results-actions .btn.tertiary:hover {
    color: var(--sudoku-text);
    border-color: rgba(255, 255, 255, 0.18);
    background: rgba(255, 255, 255, 0.05);
}

.results-overlay::before {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 20% 20%, rgba(78, 205, 196, 0.15), transparent 55%),
                radial-gradient(circle at 80% 10%, rgba(94, 94, 255, 0.12), transparent 58%);
    pointer-events: none;
}

.sudoku-confetti-piece {
    position: absolute;
    width: 10px;
    height: 18px;
    border-radius: 3px;
    opacity: 0;
    animation: confettiFall 1.6s ease-out forwards;
}

@keyframes confettiFall {
    0% {
        transform: translate3d(0, -20px, 0) rotate(0deg);
        opacity: 0;
    }
    15% {
        opacity: 1;
    }
    100% {
        transform: translate3d(var(--drift, 40px), 180px, 0) rotate(360deg);
        opacity: 0;
    }
}

.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(4, 8, 18, 0.65);
    backdrop-filter: blur(6px);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 180;
}

.modal-overlay.active {
    display: flex;
}

.shake {
    animation: shake 0.35s ease;
}

@keyframes shake {
    10%, 90% { transform: translateX(-1px); }
    20%, 80% { transform: translateX(2px); }
    30%, 50%, 70% { transform: translateX(-3px); }
    40%, 60% { transform: translateX(3px); }
}

@keyframes cellConflict {
    0% { background: var(--sudoku-conflict); }
    100% { background: rgba(255, 107, 107, 0.03); }
}

/* Responsiveness */
@media (max-width: 1200px) {
    .sudoku-layout {
        grid-template-columns: 220px minmax(0, 1fr) 220px;
    }
}

@media (max-width: 1024px) {
    .sudoku-layout {
        grid-template-columns: minmax(0, 1fr);
    }

    .sudoku-sidebar {
        order: 2;
    }

    .sudoku-sidebar-right {
        order: 3;
        position: sticky;
        bottom: 0;
        z-index: 150;
        background: rgba(12, 12, 20, 0.82);
        backdrop-filter: blur(10px);
        box-shadow: 0 -12px 30px rgba(0, 0, 0, 0.35);
    }

    .number-pad button {
        height: 50px;
    }

    .sudoku-board {
        width: min(90vw, 520px);
    }
}

@media (max-width: 768px) {
    body.sudoku-theme {
        overflow-x: hidden;
        width: 100%;
        max-width: 100%;
    }

    #sudoku-app {
        width: 100%;
        max-width: 100%;
        overflow-x: hidden;
    }

    /* Defer menu padding to shared .game-menu-container */
    .game-menu-title h1 {
        font-size: 2.6rem;
    }

    .sudoku-menu-stats {
        grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    }

    .game-menu-button {
        padding: 16px 18px;
    }

    .sudoku-daily-preview {
        flex-direction: column;
        align-items: stretch;
    }

    .sudoku-game-screen {
        padding: 0 8px 120px;
        min-height: 100vh;
    }

    .results-actions {
        flex-direction: column;
    }

    .sudoku-layout {
        display: flex;
        flex-direction: column;
        gap: 12px;
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
        padding: 0;
        margin: 0;
    }

    .sudoku-board-wrapper {
        order: 1;
        width: 100%;
        max-width: 100%;
        margin: 0;
        padding: 8px;
        border-radius: 20px;
        box-sizing: border-box;
    }

    .sudoku-sidebar-right.spare-controls {
        order: 2;
        position: static;
        z-index: 10;
        background: var(--sudoku-surface);
        backdrop-filter: none;
        border-radius: 20px;
        border: 1px solid rgba(255, 255, 255, 0.08);
        padding: 12px;
        box-shadow: none;
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
    }

    .sudoku-sidebar-right.spare-controls .number-pad {
        grid-template-columns: repeat(3, minmax(0, 1fr));
        gap: 8px;
    }

    .sudoku-sidebar-right.spare-controls .number-pad button {
        height: 52px;
        font-size: 1.2rem;
        font-weight: 700;
        border-radius: 12px;
        padding: 0;
    }

    .sudoku-sidebar-right.spare-controls .number-pad button.wide {
        height: 48px;
        font-size: 0.95rem;
        margin-top: 4px;
    }

    .sudoku-sidebar-right.spare-controls .tool-buttons {
        flex-wrap: wrap;
        gap: 8px;
    }

    .sudoku-sidebar-right.spare-controls .tool-buttons .tool-btn {
        flex: 1 1 calc(50% - 8px);
        justify-content: center;
        min-width: 140px;
    }

    .sudoku-board {
        width: 100%;
        max-width: 100%;
        margin: 0;
        box-sizing: border-box;
        aspect-ratio: 1 / 1;
    }

    .sudoku-board[data-size="4"] {
        width: 100%;
        max-width: 100%;
        aspect-ratio: 1 / 1;
    }

    .sudoku-sidebar {
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
    }

    .sudoku-sidebar-left {
        order: 3;
        padding: 12px;
        border-radius: 20px;
        border: 1px solid rgba(255, 255, 255, 0.08);
        background: var(--sudoku-surface);
        gap: 12px;
    }

    .sudoku-sidebar-left .sudoku-status-cards,
    .sudoku-sidebar-left .sudoku-progress {
        display: none;
    }

    .sudoku-sidebar-left .tool-buttons {
        display: grid;
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 10px;
    }

    .sudoku-sidebar-left .tool-buttons .tool-btn {
        min-width: 0;
        justify-content: center;
    }

    .sudoku-sidebar-left .tool-buttons #sudoku-hint-btn {
        display: none;
    }

    .sudoku-sidebar-right .sudoku-toggles,
    .sudoku-sidebar-right .sudoku-settings {
        display: none;
    }
}

@media (max-width: 520px) {
    .sudoku-game-screen {
        padding: 0 6px 100px;
    }

    .sudoku-layout {
        gap: 10px;
    }

    .sudoku-board-wrapper {
        width: 100%;
        max-width: 100%;
        margin: 0;
        padding: 6px;
        box-sizing: border-box;
    }

    .sudoku-board {
        width: 100%;
        max-width: 100%;
        margin: 0;
        box-sizing: border-box;
    }

    .sudoku-board[data-size="4"] {
        width: 100%;
        max-width: 100%;
    }

    .sudoku-sidebar-right.spare-controls {
        padding: 10px;
    }

    .sudoku-sidebar-right.spare-controls .number-pad {
        gap: 6px;
    }

    .sudoku-sidebar-right.spare-controls .number-pad button {
        height: 48px;
        font-size: 1.1rem;
    }

    .sudoku-sidebar-right.spare-controls .number-pad button.wide {
        height: 44px;
        font-size: 0.9rem;
    }

    .sudoku-sidebar-left {
        padding: 10px;
    }

    .toast-container {
        bottom: 20px;
        left: 50%;
        right: auto;
        transform: translateX(-50%);
    }

    .sudoku-sidebar-left .tool-buttons {
        grid-template-columns: 1fr;
    }

    .sudoku-sidebar-left .tool-buttons .tool-btn,
    .sudoku-sidebar-left .tool-buttons .undo-redo .tool-btn {
        min-width: 0;
        width: 100%;
    }

    .sudoku-sidebar-left .undo-redo {
        width: 100%;
    }

    .results-panel {
        padding: 28px 20px 26px;
    }

    .results-icon {
        width: 76px;
        height: 76px;
        font-size: 2rem;
    }

    .results-stats {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .results-actions {
        flex-direction: column;
    }

    .results-actions .btn {
        width: 100%;
    }
}

body[data-colour-blind="on"] .sudoku-cell.selected {
    background: rgba(78, 205, 196, 0.35);
}

body[data-colour-blind="on"] .sudoku-cell.match {
    background: rgba(153, 193, 241, 0.18);
    box-shadow: inset 0 0 0 1px rgba(153, 193, 241, 0.5);
}

body[data-colour-blind="on"] .sudoku-cell.selected.match {
    background: rgba(78, 205, 196, 0.35);
    box-shadow: inset 0 0 0 2px rgba(78, 205, 196, 0.7);
}

body[data-colour-blind="on"] .sudoku-cell.conflict {
    background: rgba(244, 162, 97, 0.2);
}

body[data-colour-blind="on"] .pencil-marks span.match {
    background: rgba(153, 193, 241, 0.14);
    color: #0b1f36;
}

body[data-sudoku-theme="light"] .sudoku-cell.match {
    background: rgba(255, 183, 77, 0.14);
    box-shadow: inset 0 0 0 1px rgba(255, 183, 77, 0.4);
    color: #3f2800;
}

body[data-sudoku-theme="light"] .sudoku-cell.selected.match {
    background: rgba(78, 205, 196, 0.22);
    box-shadow: inset 0 0 0 2px rgba(78, 205, 196, 0.6);
    color: #0b1f36;
}

body[data-sudoku-theme="light"] .pencil-marks span.match {
    background: rgba(255, 183, 77, 0.14);
    color: #3f2800;
}

body.timer-hidden .status-card .timer-value {
    visibility: hidden;
}

.calendar-day::after {
    content: "";
    position: absolute;
    inset: 15%;
    border-radius: 5px;
    background: linear-gradient(135deg, rgba(78, 205, 196, 0.55), rgba(78, 205, 196, 0.85));
}

.modal::-webkit-scrollbar {
    width: 10px;
}

.modal::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 999px;
}

.modal::-webkit-scrollbar-track {
    background: transparent;
}