* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

:root {
    --primary: #58cc02;
    --primary-dark: #4ea300;
    --primary-light: #ebf9d8;
    --secondary: #2b70c9;
    --accent: #ffc800;
    --danger: #ef5350;
    --danger-soft: #ffe6e5;
    --bg: #f5f7f1;
    --card: rgba(255, 255, 255, 0.98);
    --text: #3c3c3c;
    --text-soft: #737373;
    --border: #e5e5e5;
    --line-soft: rgba(60, 60, 60, 0.08);
    --shadow: 0 12px 30px rgba(60, 60, 60, 0.06);
    --shell-width: 1080px;
    --board-max: 720px;
}

body {
    min-height: 100vh;
    background: var(--bg);
    color: var(--text);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Nunito", sans-serif;
}

body::before {
    content: none;
}

#app {
    position: relative;
    min-height: 100vh;
}

.back-link {
    position: fixed;
    top: 18px;
    left: 18px;
    z-index: 30;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.92);
    border: 1px solid rgba(88, 204, 2, 0.18);
    box-shadow: 0 10px 24px rgba(60, 60, 60, 0.08);
    color: var(--primary);
    text-decoration: none;
    font-size: 14px;
    font-weight: 700;
    transition: transform 0.2s ease, box-shadow 0.2s ease, color 0.2s ease;
}

.back-link:hover {
    transform: translateX(-2px);
    box-shadow: 0 14px 30px rgba(60, 60, 60, 0.12);
    color: var(--primary-dark);
}

.page-shell {
    width: min(calc(100% - 24px), var(--shell-width));
    margin: 0 auto;
    padding: 88px 0 32px;
}

.panel,
.board-panel,
.keypad-panel,
.menu-panel,
.hud-panel,
.overlay-card {
    background: var(--card);
    border: 1px solid rgba(88, 204, 2, 0.15);
    box-shadow: var(--shadow);
}

.menu-layout {
    display: grid;
    gap: 18px;
    max-width: 660px;
}

.menu-panel {
    border-radius: 28px;
    padding: 28px;
    display: grid;
    gap: 24px;
}

.menu-title {
    font-size: clamp(30px, 5vw, 38px);
    font-weight: 900;
    letter-spacing: -0.04em;
    line-height: 1.05;
    text-align: center;
}

.menu-block {
    display: grid;
    gap: 12px;
}

.menu-block-title,
.preview-title,
.panel-title {
    font-size: 15px;
    font-weight: 800;
    text-align: center;
}

.menu-summary-head,
.preview-card-head,
.panel-head {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 12px;
}

.preview-subtitle,
.panel-copy {
    margin-top: 4px;
    color: var(--text-soft);
    font-size: 12px;
    line-height: 1.6;
}

.difficulty-pill {
    padding: 8px 12px;
    border-radius: 14px;
    background: rgba(43, 112, 201, 0.12);
    color: var(--secondary);
    font-size: 12px;
    font-weight: 800;
    white-space: nowrap;
}

.menu-mini-board {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 8px;
    padding: 14px;
    border-radius: 22px;
    background: #f6fbef;
    border: 1px solid rgba(88, 204, 2, 0.14);
}

.sudoku-preview-cell {
    aspect-ratio: 1 / 1;
    border-radius: 12px;
    background: white;
    border: 1px solid rgba(60, 60, 60, 0.08);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 22px;
    font-weight: 900;
    color: var(--primary-dark);
}

.sudoku-preview-cell.muted {
    color: rgba(88, 167, 0, 0.28);
}

.preview-meta {
    display: grid;
    gap: 10px;
}

.meta-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 10px;
    padding: 12px 14px;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.86);
    border: 1px solid var(--line-soft);
    font-size: 13px;
}

.meta-row strong {
    font-size: 14px;
}

.choice-grid {
    display: grid;
    gap: 12px;
}

.choice-grid.two-col {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.choice-grid.three-col {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.choice-btn {
    width: 100%;
    border: 1px solid var(--line-soft);
    border-radius: 18px;
    min-height: 72px;
    padding: 16px 12px;
    background: #ffffff;
    color: inherit;
    text-align: center;
    cursor: pointer;
    transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease, background 0.18s ease;
}

.choice-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 12px 28px rgba(60, 60, 60, 0.08);
    border-color: rgba(88, 204, 2, 0.3);
}

.choice-btn.is-active {
    background: #f3faea;
    border-color: rgba(88, 204, 2, 0.38);
}

.choice-main {
    display: block;
    font-size: 17px;
    font-weight: 900;
}

.choice-sub {
    display: block;
    margin-top: 6px;
    color: var(--text-soft);
    font-size: 12px;
    line-height: 1.6;
}

.selection-summary {
    display: grid;
    gap: 6px;
}

.menu-summary {
    display: grid;
    gap: 14px;
    padding: 18px;
    border-radius: 22px;
    background: #fbfdf8;
    border: 1px solid rgba(88, 204, 2, 0.14);
}

.menu-summary-meta {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.selection-main {
    font-size: 18px;
    font-weight: 900;
}

.selection-sub {
    color: var(--text-soft);
    font-size: 13px;
}

.primary-btn,
.secondary-btn,
.ghost-btn,
.keypad-btn {
    border: none;
    cursor: pointer;
    transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.primary-btn {
    padding: 16px 22px;
    border-radius: 18px;
    background: var(--primary);
    color: white;
    font-size: 15px;
    font-weight: 900;
    box-shadow: 0 10px 20px rgba(88, 204, 2, 0.18);
}

.primary-btn:hover {
    transform: translateY(-1px);
}

.secondary-btn,
.ghost-btn {
    padding: 12px 14px;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.82);
    color: var(--text);
    border: 1px solid var(--line-soft);
    font-size: 13px;
    font-weight: 800;
}

.secondary-btn:hover,
.ghost-btn:hover,
.keypad-btn:hover {
    transform: translateY(-1px);
}

.secondary-btn.is-active {
    background: rgba(43, 112, 201, 0.1);
    border-color: rgba(43, 112, 201, 0.32);
    color: var(--secondary);
}

.play-layout {
    display: grid;
    gap: 16px;
}

.hud-panel-compact {
    gap: 16px;
}

.hud-topbar {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 16px;
}

.hud-utility-actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: 10px;
}

.hud-panel {
    border-radius: 26px;
    padding: 18px;
    display: grid;
    gap: 18px;
}

.hud-left {
    display: grid;
    gap: 10px;
}

.hud-title-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 10px;
}

.hud-title {
    font-size: clamp(26px, 4vw, 34px);
    font-weight: 900;
    letter-spacing: -0.04em;
    line-height: 1;
}

.hud-title span {
    color: var(--secondary);
}

.hud-tag {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    border-radius: 999px;
    background: rgba(88, 204, 2, 0.12);
    color: var(--primary-dark);
    font-size: 12px;
    font-weight: 900;
}

.hud-subtitle {
    color: var(--text-soft);
    font-size: 13px;
    line-height: 1.6;
}

.hud-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.stat-chip {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 14px;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.88);
    border: 1px solid var(--line-soft);
    font-size: 13px;
    font-weight: 800;
}

.stat-chip strong {
    font-size: 15px;
}

.stat-chip.is-danger {
    background: var(--danger-soft);
    border-color: rgba(239, 83, 80, 0.18);
    color: #b9413f;
}

.play-main {
    display: grid;
    gap: 16px;
    grid-template-columns: minmax(0, 1fr) minmax(280px, 320px);
    align-items: start;
}

.play-main-compact {
    grid-template-columns: minmax(0, 1fr);
    width: min(100%, calc(var(--board-max) + 52px));
    margin: 0 auto;
}

.board-panel {
    border-radius: 28px;
    padding: 16px;
}

.board-panel-stack {
    display: grid;
    gap: 16px;
    width: 100%;
}

.board-panel-size-4 {
    max-width: 520px;
    margin: 0 auto;
}

.board-panel-size-6 {
    max-width: 640px;
    margin: 0 auto;
}

.board-panel-size-9 {
    max-width: 772px;
    margin: 0 auto;
}

.toolbar-panel {
    display: grid;
    gap: 12px;
    padding: 14px;
    border-radius: 22px;
    background: #f6fbef;
    border: 1px solid rgba(88, 204, 2, 0.14);
}

.board-frame {
    width: 100%;
    margin: 0 auto;
    padding: 14px;
    border-radius: 26px;
    background: #f6fbef;
    border: 1px solid rgba(88, 204, 2, 0.14);
}

.board-frame-size-4 {
    max-width: 484px;
}

.board-frame-size-6 {
    max-width: 604px;
}

.board-frame-size-9 {
    max-width: var(--board-max);
}

.board-grid {
    display: grid;
    width: 100%;
    aspect-ratio: 1 / 1;
    border-radius: 20px;
    overflow: hidden;
    background: white;
    border: 2px solid rgba(88, 204, 2, 0.14);
}

.cell {
    position: relative;
    border: none;
    background: white;
    color: var(--text);
    font: inherit;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 0;
    min-height: 0;
    transition: background 0.16s ease, transform 0.16s ease, color 0.16s ease;
}

.cell::before {
    content: "";
    position: absolute;
    inset: 0;
    border-right: 1px solid rgba(60, 60, 60, 0.08);
    border-bottom: 1px solid rgba(60, 60, 60, 0.08);
    pointer-events: none;
}

.cell.is-related {
    background: rgba(88, 204, 2, 0.08);
}

.cell.is-same {
    background: rgba(43, 112, 201, 0.12);
}

.cell.is-selected {
    background: rgba(88, 204, 2, 0.18);
    box-shadow: inset 0 0 0 2px rgba(88, 204, 2, 0.46);
}

.cell.is-fixed {
    background: #fbfff6;
}

.cell.is-wrong {
    animation: wrongPulse 0.36s ease;
    background: var(--danger-soft);
}

.cell-value {
    position: relative;
    z-index: 1;
    font-weight: 900;
    line-height: 1;
}

.cell.is-fixed .cell-value {
    color: var(--primary-dark);
}

.cell:not(.is-fixed) .cell-value {
    color: var(--secondary);
}

.board-size-4 .cell-value {
    font-size: clamp(22px, 7vw, 38px);
}

.board-size-6 .cell-value {
    font-size: clamp(18px, 5vw, 32px);
}

.board-size-9 .cell-value {
    font-size: clamp(18px, 4vw, 30px);
}

.notes-grid {
    position: relative;
    z-index: 1;
    width: 100%;
    height: 100%;
    display: grid;
    place-items: center;
    padding: 6px;
}

.notes-grid.notes-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    grid-template-rows: repeat(2, minmax(0, 1fr));
}

.notes-grid.notes-6 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    grid-template-rows: repeat(2, minmax(0, 1fr));
}

.notes-grid.notes-9 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    grid-template-rows: repeat(3, minmax(0, 1fr));
}

.note-slot {
    font-size: clamp(9px, 1.7vw, 13px);
    font-weight: 700;
    color: rgba(43, 112, 201, 0.78);
}

.keypad-panel {
    border-radius: 28px;
    padding: 18px;
    display: grid;
    gap: 14px;
}

.keypad-panel-dock {
    align-self: start;
}

.selection-status {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 14px 16px;
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.9);
    border: 1px solid var(--line-soft);
}

.selection-copy {
    display: grid;
    gap: 4px;
}

.selection-title {
    font-size: 15px;
    font-weight: 900;
}

.selection-detail {
    color: var(--text-soft);
    font-size: 12px;
    line-height: 1.5;
}

.selection-badge {
    flex-shrink: 0;
    padding: 8px 10px;
    border-radius: 14px;
    background: rgba(88, 204, 2, 0.12);
    color: var(--primary-dark);
    font-size: 12px;
    font-weight: 900;
}

.selection-badge.is-note {
    background: rgba(43, 112, 201, 0.12);
    color: var(--secondary);
}

.selection-badge.is-fixed {
    background: rgba(60, 60, 60, 0.08);
    color: var(--text);
}

.digit-dock {
    display: grid;
    grid-template-columns: repeat(9, minmax(0, 1fr));
    gap: 10px;
}

.digit-btn {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 54px;
    border-radius: 16px;
    border: 1px solid rgba(88, 204, 2, 0.14);
    background: #ffffff;
    color: var(--secondary);
    cursor: pointer;
    box-shadow: 0 8px 18px rgba(60, 60, 60, 0.05);
    transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease, background 0.18s ease;
}

.digit-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 12px 22px rgba(60, 60, 60, 0.08);
}

.digit-btn.is-selected {
    border-color: rgba(43, 112, 201, 0.36);
    background: rgba(43, 112, 201, 0.08);
}

.digit-btn.is-complete {
    color: var(--primary-dark);
    background: #f3faea;
    border-color: rgba(88, 204, 2, 0.26);
}

.digit-main {
    font-size: 24px;
    font-weight: 900;
    line-height: 1;
}

.digit-count {
    position: absolute;
    top: 7px;
    right: 9px;
    font-size: 11px;
    font-weight: 800;
    color: var(--text-soft);
}

.control-actions {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.control-actions-four {
    grid-template-columns: repeat(4, minmax(0, 1fr));
}

.panel-head {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 12px;
}

.panel-title {
    font-size: 16px;
    font-weight: 900;
}

.panel-copy {
    margin-top: 4px;
    color: var(--text-soft);
    font-size: 12px;
    line-height: 1.6;
}

.hint-pill {
    padding: 8px 10px;
    border-radius: 14px;
    background: rgba(255, 200, 0, 0.18);
    color: #9b7a00;
    font-size: 12px;
    font-weight: 900;
}

.selection-card {
    padding: 14px 16px;
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.88);
    border: 1px solid var(--line-soft);
}

.selection-label {
    font-size: 12px;
    color: var(--text-soft);
}

.selection-value {
    margin-top: 6px;
    font-size: 16px;
    font-weight: 900;
}

.selection-value small {
    display: block;
    margin-top: 4px;
    color: var(--text-soft);
    font-size: 12px;
    font-weight: 600;
}

.keypad-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(58px, 1fr));
    gap: 10px;
}

.keypad-btn {
    min-height: 56px;
    border-radius: 16px;
    background: white;
    border: 1px solid var(--line-soft);
    color: var(--secondary);
    font-size: 22px;
    font-weight: 900;
}

.keypad-btn.is-utility {
    min-height: 50px;
    font-size: 13px;
    color: var(--text);
}

.action-row {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.toast {
    min-height: 46px;
    padding: 12px 14px;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.88);
    border: 1px solid var(--line-soft);
    color: var(--text-soft);
    font-size: 13px;
    line-height: 1.6;
}

.toast.is-danger {
    background: var(--danger-soft);
    border-color: rgba(239, 83, 80, 0.18);
    color: #b9413f;
}

.toast.is-success {
    background: rgba(88, 204, 2, 0.14);
    border-color: rgba(88, 204, 2, 0.18);
    color: var(--primary-dark);
}

.overlay {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    background: rgba(28, 34, 42, 0.34);
    backdrop-filter: blur(8px);
    z-index: 35;
}

.overlay-card {
    width: min(100%, 420px);
    border-radius: 26px;
    padding: 24px;
    display: grid;
    gap: 14px;
}

.overlay-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    border-radius: 999px;
    background: rgba(88, 204, 2, 0.12);
    color: var(--primary-dark);
    font-size: 12px;
    font-weight: 900;
}

.overlay-title {
    font-size: 28px;
    font-weight: 900;
    letter-spacing: -0.04em;
}

.overlay-copy {
    color: var(--text-soft);
    font-size: 14px;
    line-height: 1.7;
}

.overlay-stats {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.overlay-stat {
    padding: 12px;
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.86);
    border: 1px solid var(--line-soft);
}

.overlay-stat span {
    display: block;
    color: var(--text-soft);
    font-size: 12px;
}

.overlay-stat strong {
    display: block;
    margin-top: 6px;
    font-size: 18px;
}

.overlay-actions {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.loading-state,
.error-state {
    min-height: calc(100vh - 140px);
    display: grid;
    place-items: center;
}

.status-card {
    width: min(100%, 520px);
    padding: 28px;
    border-radius: 28px;
    background: rgba(255, 255, 255, 0.96);
    border: 1px solid rgba(88, 204, 2, 0.15);
    box-shadow: var(--shadow);
    text-align: center;
}

.status-title {
    font-size: 26px;
    font-weight: 900;
    letter-spacing: -0.04em;
}

.status-copy {
    margin-top: 12px;
    color: var(--text-soft);
    font-size: 14px;
    line-height: 1.8;
}

.status-actions {
    margin-top: 18px;
    display: inline-flex;
    gap: 10px;
}

@keyframes wrongPulse {
    0% { transform: scale(1); }
    30% { transform: scale(0.96); }
    65% { transform: scale(1.02); }
    100% { transform: scale(1); }
}

@media (max-width: 980px) {
    .play-main {
        grid-template-columns: 1fr;
    }

    .hud-topbar {
        flex-direction: column;
        align-items: stretch;
    }

    .hud-utility-actions {
        justify-content: flex-start;
    }
}

@media (max-width: 720px) {
    .back-link {
        position: static;
        margin: 18px 0 0 12px;
    }

    .page-shell {
        width: min(calc(100% - 8px), var(--shell-width));
        padding-top: 16px;
    }

    .menu-panel,
    .hud-panel,
    .board-panel,
    .keypad-panel,
    .overlay-card,
    .status-card {
        border-radius: 22px;
        padding: 18px;
    }

    .choice-grid.three-col {
        gap: 10px;
    }

    .choice-btn {
        min-height: 64px;
        padding: 12px 8px;
    }

    .choice-main {
        font-size: 16px;
    }

    .choice-sub {
        font-size: 11px;
    }

    .hud-title {
        font-size: 28px;
    }

    .hud-stats {
        gap: 8px;
    }

    .stat-chip {
        flex: 1 1 calc(50% - 8px);
        justify-content: center;
    }

    .board-panel {
        padding: 10px;
    }

    .toolbar-panel {
        padding: 12px;
    }

    .board-frame {
        padding: 10px;
        border-radius: 22px;
    }

    .selection-status {
        align-items: flex-start;
        padding: 12px;
        gap: 10px;
    }

    .selection-title {
        font-size: 14px;
    }

    .selection-detail {
        font-size: 11px;
    }

    .selection-badge {
        padding: 7px 9px;
        font-size: 11px;
    }

    .digit-dock {
        gap: 8px;
    }

    .digit-btn {
        min-height: 46px;
        border-radius: 12px;
    }

    .digit-main {
        font-size: 21px;
    }

    .control-actions {
        grid-template-columns: repeat(4, minmax(0, 1fr));
        gap: 8px;
    }

    .action-row,
    .overlay-actions {
        grid-template-columns: 1fr;
    }

    .overlay-stats {
        grid-template-columns: 1fr;
    }
}