html {
    color-scheme: light;
    scroll-behavior: smooth;
}

body {
    --page-bg: #f6f7f9;
    --surface: #ffffff;
    --surface-strong: #eef3f8;
    --text-color: #1f2933;
    --muted-text: #52616f;
    --border: #d3dae3;
    --button-bg: #166534;
    --button-text: #ffffff;
    --button-hover: #14532d;
    --accent: #b45309;
    --board-border: #52616f;
    --cell-bg: #dfe6ee;
    --cell-border: #aeb9c7;
    --cell-text: #1f2933;
    --revealed-bg: #ffffff;
    --mine-bg: #dc2626;
    --flagged-bg: #facc15;
    --shadow: rgba(31, 41, 51, 0.12);
    margin: 0;
    background: var(--page-bg);
    color: var(--text-color);
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.65;
}

body.dark-theme {
    --page-bg: #101418;
    --surface: #18212a;
    --surface-strong: #202b36;
    --text-color: #edf2f7;
    --muted-text: #c5ced8;
    --border: #3c4a57;
    --button-bg: #8bc34a;
    --button-text: #101418;
    --button-hover: #a3d46c;
    --accent: #f6ad55;
    --board-border: #7b8794;
    --cell-bg: #263442;
    --cell-border: #485766;
    --cell-text: #edf2f7;
    --revealed-bg: #111820;
    --mine-bg: #ef4444;
    --flagged-bg: #d69e2e;
    --shadow: rgba(0, 0, 0, 0.34);
}

* {
    box-sizing: border-box;
}

a {
    color: inherit;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 10;
    background: color-mix(in srgb, var(--surface) 92%, transparent);
    border-bottom: 1px solid var(--border);
    backdrop-filter: blur(12px);
}

.nav {
    width: min(1120px, calc(100% - 32px));
    margin: 0 auto;
    min-height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.brand {
    font-weight: 800;
    text-decoration: none;
    white-space: nowrap;
}

.nav-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: 14px;
    color: var(--muted-text);
    font-size: 0.95rem;
}

.nav-links a,
.site-footer a {
    text-decoration: none;
}

.nav-links a:hover,
.site-footer a:hover {
    text-decoration: underline;
}

main {
    width: min(1120px, calc(100% - 32px));
    margin: 0 auto;
}

.hero {
    min-height: 560px;
    display: grid;
    grid-template-columns: minmax(0, 1fr) 360px;
    align-items: center;
    gap: 56px;
    padding: 56px 0 72px;
}

.hero-copy h1 {
    margin: 0 0 18px;
    font-size: clamp(2.4rem, 7vw, 5rem);
    line-height: 1.05;
    letter-spacing: 0;
}

.hero-copy p {
    max-width: 640px;
    margin: 0 0 24px;
    color: var(--muted-text);
    font-size: 1.1rem;
}

.eyebrow {
    margin: 0 0 8px;
    color: var(--accent);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0;
    text-transform: uppercase;
}

.primary-link,
button {
    display: inline-flex;
    min-height: 40px;
    align-items: center;
    justify-content: center;
    border: 1px solid transparent;
    border-radius: 6px;
    background: var(--button-bg);
    color: var(--button-text);
    cursor: pointer;
    font: inherit;
    font-weight: 700;
    padding: 0 14px;
    text-decoration: none;
}

.primary-link:hover,
button:hover {
    background: var(--button-hover);
}

.hero-board {
    display: grid;
    grid-template-columns: repeat(5, 52px);
    gap: 6px;
    justify-content: center;
    padding: 22px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: 0 18px 44px var(--shadow);
}

.hero-board span {
    width: 52px;
    height: 52px;
    display: grid;
    place-items: center;
    background: var(--cell-bg);
    border: 1px solid var(--cell-border);
    color: var(--cell-text);
    font-weight: 800;
}

.play-section,
.content-section,
.partner-contact,
.text-page {
    padding: 56px 0;
    border-top: 1px solid var(--border);
}

.section-heading {
    max-width: 760px;
    margin-bottom: 24px;
}

.section-heading h2,
.text-page h1 {
    margin: 0 0 10px;
    font-size: clamp(1.7rem, 4vw, 2.6rem);
    line-height: 1.2;
    letter-spacing: 0;
}

.section-heading p,
.partner-contact p,
.text-page p {
    color: var(--muted-text);
}

.game-shell {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 320px;
    gap: 24px;
    align-items: start;
}

.game-panel,
.quick-guide,
.leaderboard,
.practice-card,
.activity-list,
.resource-grid article,
.film-list article,
.notice-box,
.article-grid article,
.strategy-list article,
.faq-list details {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 10px 28px var(--shadow);
}

.game-panel {
    padding: 18px;
    overflow: hidden;
}

.controls {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    align-items: center;
    margin-bottom: 14px;
}

.controls label,
.quick-guide li,
.partner-contact label {
    color: var(--muted-text);
}

select,
input,
textarea {
    width: 100%;
    min-height: 40px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--surface);
    color: var(--text-color);
    font: inherit;
    padding: 0 10px;
}

select {
    width: auto;
}

textarea {
    min-height: 130px;
    padding: 10px;
    resize: vertical;
}

.status {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px;
    margin-bottom: 14px;
    color: var(--muted-text);
    font-size: 0.95rem;
}

.status div {
    min-height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 10px;
    background: var(--surface-strong);
    border: 1px solid var(--border);
    border-radius: 6px;
    text-align: center;
}

.board-wrap {
    width: 100%;
    overflow: auto;
    padding-bottom: 4px;
}

#game-board {
    display: grid;
    width: max-content;
    border: 1px solid var(--board-border);
    box-shadow: 0 8px 20px var(--shadow);
    touch-action: manipulation;
}

.cell {
    width: 30px;
    height: 30px;
    border: 1px solid var(--cell-border);
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--cell-bg);
    color: var(--cell-text);
    cursor: pointer;
    font-weight: 800;
    user-select: none;
}

.cell:focus-visible {
    outline: 3px solid var(--accent);
    outline-offset: -3px;
}

.cell:disabled {
    opacity: 1;
    color: var(--cell-text);
    cursor: default;
}

.cell.mine:disabled {
    color: #ffffff;
}

.cell.revealed {
    background: var(--revealed-bg);
}

.cell.mine {
    background: var(--mine-bg);
    color: #ffffff;
}

.cell.flagged {
    background: var(--flagged-bg);
    color: #1f2933;
}

.side-column {
    display: grid;
    gap: 18px;
}

.quick-guide,
.leaderboard {
    padding: 18px;
}

.quick-guide h3,
.leaderboard h3,
.activity-list h3,
.resource-grid h3,
.article-grid h3,
.strategy-list h3 {
    margin-top: 0;
}

.quick-guide ul {
    margin: 0;
    padding-left: 20px;
}

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

.leaderboard-header h3 {
    margin-bottom: 0;
}

#clear-records {
    min-height: 34px;
    padding: 0 10px;
    background: transparent;
    border-color: var(--border);
    color: var(--text-color);
    font-size: 0.9rem;
}

#clear-records:hover {
    background: var(--surface-strong);
}

.leaderboard-note {
    margin: 8px 0 14px;
    color: var(--muted-text);
    font-size: 0.92rem;
}

.leaderboard-list {
    display: grid;
    gap: 8px;
    margin: 0;
    padding: 0;
    list-style: none;
}

.leaderboard-list li {
    display: grid;
    grid-template-columns: 28px minmax(0, 1fr) auto;
    gap: 8px;
    align-items: center;
    min-height: 38px;
    padding: 8px 10px;
    background: var(--surface-strong);
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.92rem;
}

.leaderboard-list .rank {
    width: 24px;
    height: 24px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: var(--surface);
    border: 1px solid var(--border);
    font-weight: 800;
}

.leaderboard-list .player {
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-weight: 700;
}

.leaderboard-list .record-time {
    font-weight: 800;
    color: var(--accent);
}

.leaderboard-list .record-date {
    grid-column: 2 / 4;
    color: var(--muted-text);
    font-size: 0.82rem;
}

.leaderboard-list .leaderboard-empty {
    display: block;
    color: var(--muted-text);
    text-align: center;
}

.practice-shell {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 320px;
    gap: 24px;
    align-items: start;
}

.practice-card {
    display: grid;
    grid-template-columns: 220px minmax(0, 1fr);
    gap: 24px;
    padding: 20px;
}

.practice-board {
    display: grid;
    grid-template-columns: repeat(3, 56px);
    gap: 6px;
    align-content: start;
}

.practice-cell {
    width: 56px;
    height: 56px;
    display: grid;
    place-items: center;
    border: 1px solid var(--cell-border);
    background: var(--revealed-bg);
    color: var(--cell-text);
    font-weight: 800;
}

.practice-cell.unknown {
    background: var(--cell-bg);
}

.practice-cell.flagged {
    background: var(--flagged-bg);
    color: #1f2933;
}

.practice-copy h3 {
    margin: 0 0 8px;
    font-size: 1.35rem;
}

.practice-options {
    display: grid;
    gap: 8px;
    margin: 16px 0;
}

.practice-options button {
    width: 100%;
    justify-content: flex-start;
    background: var(--surface-strong);
    border-color: var(--border);
    color: var(--text-color);
    text-align: left;
}

.practice-options button:hover {
    background: var(--button-bg);
    color: var(--button-text);
}

.practice-feedback {
    min-height: 54px;
    padding: 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--surface-strong);
    color: var(--muted-text);
}

.practice-feedback.is-correct {
    border-color: #15803d;
    color: #15803d;
}

.practice-feedback.is-wrong {
    border-color: #b45309;
    color: var(--accent);
}

.activity-list {
    padding: 18px;
}

.activity-list ol,
.resource-grid ul,
.check-list,
.rich-list {
    padding-left: 20px;
}

.activity-list li,
.resource-grid li,
.check-list li,
.rich-list li {
    margin-bottom: 8px;
    color: var(--muted-text);
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.resource-grid.compact {
    margin-top: 16px;
}

.resource-grid article {
    padding: 20px;
}

.resource-grid dl {
    margin: 0;
}

.resource-grid dt {
    margin-top: 12px;
    font-weight: 800;
}

.resource-grid dd {
    margin: 4px 0 0;
    color: var(--muted-text);
}

.more-link {
    margin-top: 22px;
    font-weight: 800;
}

.resource-page section {
    margin-top: 36px;
}

.notice-box {
    padding: 20px;
    border-color: #b45309;
    background: color-mix(in srgb, var(--surface) 82%, #fef3c7);
}

.notice-box h2 {
    margin-top: 0;
}

.film-list {
    display: grid;
    gap: 16px;
}

.film-list article {
    padding: 20px;
}

.film-list h3 {
    margin-top: 0;
}

.watch-point {
    margin-bottom: 0;
    color: var(--accent);
    font-weight: 800;
}

.source-list {
    display: grid;
    gap: 8px;
    padding-left: 20px;
}

.source-list a {
    color: var(--button-bg);
    font-weight: 700;
}

.article-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.article-grid article,
.strategy-list article {
    padding: 20px;
}

.alt {
    width: 100vw;
    margin-left: calc(50% - 50vw);
    padding-left: calc((100vw - min(1120px, calc(100vw - 32px))) / 2);
    padding-right: calc((100vw - min(1120px, calc(100vw - 32px))) / 2);
    background: var(--surface-strong);
}

.strategy-list {
    display: grid;
    gap: 16px;
}

.faq-list {
    display: grid;
    gap: 12px;
}

.faq-list details {
    padding: 16px 18px;
}

.faq-list summary {
    cursor: pointer;
    font-weight: 800;
}

.partner-contact {
    max-width: 760px;
    margin: 0 auto;
}

.partner-contact form {
    display: grid;
    gap: 10px;
    padding: 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 10px 28px var(--shadow);
}

.site-footer {
    width: min(1120px, calc(100% - 32px));
    margin: 0 auto;
    padding: 28px 0 40px;
    border-top: 1px solid var(--border);
    color: var(--muted-text);
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 16px;
}

.site-footer div {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
}

.text-page {
    max-width: 820px;
    min-height: 70vh;
}

.text-page h2 {
    margin-top: 32px;
}

.updated {
    margin-top: 32px;
    font-size: 0.95rem;
}

@media (max-width: 860px) {
    .hero,
    .game-shell,
    .article-grid,
    .practice-shell,
    .practice-card,
    .resource-grid {
        grid-template-columns: 1fr;
    }

    .hero {
        min-height: auto;
        padding-top: 36px;
        gap: 28px;
    }

    .hero-board {
        grid-template-columns: repeat(5, minmax(38px, 1fr));
        width: min(100%, 330px);
    }

    .hero-board span {
        width: 100%;
        height: auto;
        aspect-ratio: 1;
    }

    .practice-board {
        grid-template-columns: repeat(3, minmax(44px, 56px));
    }

    .practice-cell {
        width: 100%;
        height: auto;
        aspect-ratio: 1;
    }

    .status {
        grid-template-columns: 1fr;
    }

    .nav {
        align-items: flex-start;
        flex-direction: column;
        padding: 12px 0;
    }

    .nav-links {
        justify-content: flex-start;
    }
}

@media (max-width: 520px) {
    main,
    .nav,
    .site-footer {
        width: min(100% - 20px, 1120px);
    }

    .controls > * {
        flex: 1 1 130px;
    }

    .controls label {
        flex-basis: 100%;
    }

    .game-panel {
        padding: 12px;
    }

    .cell {
        width: 28px;
        height: 28px;
    }
}