/* === CSS Variables & Theme === */
:root {
    --bg: #f0ebe0;
    --bg-secondary: #e8e0d3;
    --bg-card: #faf7f0;
    --text: #3d3226;
    --text-secondary: #7a6e5e;
    --border: #c4b89e;
    --accent: #b8754a;
    --accent-hover: #a06540;
    --danger: #c97060;
    --danger-hover: #b55a4a;
    --shadow: 0 2px 8px rgba(61, 50, 38, 0.1);
    --shadow-lg: 0 6px 20px rgba(61, 50, 38, 0.15);
    --tray-outer: #8b7355;
    --tray-inner: #faf6ee;
    --tray-recess: #f0e8d8;
    --cell-size: 54px;
    --radius: 12px;
    --radius-sm: 8px;
    --font: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
}

/* Dark mode */
@media (prefers-color-scheme: dark) {
    :root {
        --bg: #1c1c2e;
        --bg-secondary: #242438;
        --bg-card: #2a2a44;
        --text: #e0dce8;
        --text-secondary: #a098b8;
        --border: #3d3858;
        --accent: #c89060;
        --accent-hover: #d4a478;
        --danger: #c97060;
        --danger-hover: #d48070;
        --shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 6px 20px rgba(0, 0, 0, 0.4);
        --tray-outer: #3d3050;
        --tray-inner: #2a2842;
        --tray-recess: #26243c;
    }
}

body.dark {
    --bg: #1c1c2e;
    --bg-secondary: #242438;
    --bg-card: #2a2a44;
    --text: #e0dce8;
    --text-secondary: #a098b8;
    --border: #3d3858;
    --accent: #c89060;
    --accent-hover: #d4a478;
    --danger: #c97060;
    --danger-hover: #d48070;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 6px 20px rgba(0, 0, 0, 0.4);
    --tray-outer: #3d3050;
    --tray-inner: #2a2842;
    --tray-recess: #26243c;
}

body.light {
    --bg: #f0ebe0;
    --bg-secondary: #e8e0d3;
    --bg-card: #faf7f0;
    --text: #3d3226;
    --text-secondary: #7a6e5e;
    --border: #c4b89e;
    --accent: #b8754a;
    --accent-hover: #a06540;
    --danger: #c97060;
    --danger-hover: #b55a4a;
    --shadow: 0 2px 8px rgba(61, 50, 38, 0.1);
    --shadow-lg: 0 6px 20px rgba(61, 50, 38, 0.15);
    --tray-outer: #8b7355;
    --tray-inner: #faf6ee;
    --tray-recess: #f0e8d8;
}

/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
    height: 100%;
    -webkit-tap-highlight-color: transparent;
    -webkit-user-select: none;
    user-select: none;
    touch-action: manipulation;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    height: 100dvh;
    display: flex;
    justify-content: center;
    transition: background 0.3s, color 0.3s;
    overflow: hidden;
}

#app {
    width: 100%;
    max-width: 600px;
    padding: 10px 14px 24px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

/* === Header === */
#header {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.title {
    font-size: 1.4rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--accent);
    cursor: pointer;
    position: relative;
    padding-right: 20px;
    transition: opacity 0.15s;
    user-select: none;
}
.title:hover {
    opacity: 0.8;
}
.title::after {
    content: '▾';
    font-size: 0.6em;
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    opacity: 0.5;
}

.header-controls {
    display: flex;
    gap: 6px;
}

.btn-icon {
    width: 38px;
    height: 38px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--accent);
    cursor: pointer;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    transition: transform 0.12s, box-shadow 0.12s;
    box-shadow: var(--shadow);
}

.btn-icon svg {
    display: block;
}

.btn-icon:active { transform: scale(0.93); }

/* Auto-mode indicator dot */
.btn-icon.theme-auto::after {
    content: '';
    position: absolute;
    bottom: 4px;
    right: 4px;
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--accent);
    opacity: 0.7;
}

/* === Date Display === */
.date-display {
    width: 100%;
    text-align: center;
    padding: 6px 12px;
    background: var(--bg-secondary);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    flex-wrap: wrap;
    font-size: 0.88rem;
}

.date-label {
    color: var(--text-secondary);
    font-weight: 500;
}

#target-date {
    font-weight: 600;
    color: var(--accent);
    font-size: 0.9rem;
}

/* === Game Area (tray + bank) === */
#game-area {
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

/* === Board Container === */
#board-container {
    position: relative;
    flex-shrink: 0;
}

#board-canvas {
    display: block;
    cursor: default;
    touch-action: none;
}

/* === Piece Bank === */
.piece-bank {
    background: var(--bg-secondary);
    border-radius: var(--radius);
    padding: 10px 12px;
    box-shadow: inset 0 1px 4px rgba(0,0,0,0.06);
    min-height: 60px;
}

.piece-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    justify-content: center;
    align-items: center;
}

.piece-item {
    cursor: grab;
    border-radius: var(--radius-sm);
    padding: 4px;
    transition: transform 0.12s, filter 0.12s;
    touch-action: none;
}

.piece-item:active { cursor: grabbing; }

.piece-item.placed {
    display: none;
}

.piece-item.dragging {
    opacity: 0.4;
    transform: scale(0.95);
}

.piece-item canvas {
    display: block;
}

/* === Controls === */
.controls {
    width: 100%;
    display: flex;
    gap: 8px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn-action {
    padding: 9px 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    font-family: var(--font);
    transition: transform 0.1s, box-shadow 0.12s, background 0.12s;
    box-shadow: var(--shadow);
    white-space: nowrap;
}

.btn-action:active { transform: scale(0.95); }
.btn-action:hover { box-shadow: var(--shadow-lg); }

.btn-action svg {
    display: inline-block;
    width: 1.1em;
    height: 1.1em;
    vertical-align: -0.15em;
    margin-right: 0.25em;
}

.btn-danger {
    border-color: var(--danger);
    color: var(--danger);
}

.btn-danger:hover {
    background: var(--danger);
    color: #fff;
}

/* === Overlay / Dialog === */
.overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    backdrop-filter: blur(3px);
    -webkit-backdrop-filter: blur(3px);
    animation: fadeIn 0.2s ease;
}

.overlay.hidden { display: none; }

.dialog {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 28px 24px;
    box-shadow: var(--shadow-lg);
    text-align: center;
    max-width: 400px;
    width: 90%;
    animation: slideUp 0.25s ease;
}

.dialog h2 { font-size: 1.4rem; margin-bottom: 12px; color: var(--accent); }
.dialog p { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: 8px; }
.dialog .btn-action { margin-top: 16px; }

.history-dialog {
    max-width: 480px;
    max-height: 70vh;
    overflow-y: auto;
}

/* === Variant Dialog === */
.variant-dialog {
    max-width: 440px;
}

/* === Help Dialog === */
.help-dialog {
    max-width: 420px;
    text-align: left;
}

.help-dialog .btn-action {
    display: block;
    margin: 16px auto 0;
}

.help-dialog h2 {
    text-align: center;
}

.help-content {
    margin: 12px 0;
}

.help-section {
    margin-bottom: 14px;
}

.help-section h3 {
    font-size: 0.95rem;
    color: var(--accent);
    margin-bottom: 6px;
    font-weight: 700;
}

.help-section ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.help-section ul li {
    position: relative;
    padding: 3px 0 3px 16px;
    font-size: 0.88rem;
    color: var(--text);
    line-height: 1.6;
}

.help-section ul li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: 700;
}

.help-section p {
    font-size: 0.88rem;
    color: var(--text);
    line-height: 1.6;
}

.help-footer {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border);
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-align: center;
}

.help-footer a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
}

.help-footer a:hover {
    text-decoration: underline;
}

.variant-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin: 14px 0 6px;
}

.variant-btn {
    padding: 12px 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text);
    cursor: pointer;
    font-family: var(--font);
    font-size: 0.92rem;
    text-align: left;
    transition: background 0.12s, border-color 0.12s;
    line-height: 1.4;
}

.variant-btn:hover {
    background: var(--bg-secondary);
}

.variant-btn.active {
    border-color: var(--accent);
    background: var(--accent);
    color: #fff;
}

.variant-btn.active strong {
    color: #fff;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
    text-align: left;
    margin: 12px 0;
}

.history-item {
    padding: 10px 14px;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 6px;
}

.history-item .date { font-weight: 600; color: var(--accent); }
.history-item .target-exposed { font-size: 0.85rem; color: var(--text-secondary); }

.lang-list {
    margin: 12px 0;
}

.lang-btn {
    display: block;
    width: 100%;
    padding: 10px 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text);
    cursor: pointer;
    font-family: var(--font);
    font-size: 0.95rem;
    transition: background 0.12s;
    flex-shrink: 0;
}

.lang-btn:hover { background: var(--bg-secondary); }
.lang-btn.active { border-color: var(--accent); background: var(--accent); color: #fff; }

.lang-divider {
    height: 1px;
    background: var(--border);
    opacity: 0.5;
    margin: 6px 0;
}

.lang-scroll {
    display: flex;
    flex-direction: column;
    gap: 6px;
    max-height: 280px;
    overflow-y: auto;
    padding-right: 4px;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { transform: translateY(20px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

/* === Landscape: bank on the right of tray === */
@media (orientation: landscape) {
    #app {
        max-width: 900px;
    }
    #game-area {
        flex-direction: row;
        align-items: flex-start;
        justify-content: center;
        gap: 12px;
    }
    #board-container {
        flex-shrink: 0;
    }
    .piece-bank {
        align-self: stretch;
        min-height: 100px;
        overflow-y: auto;
    }
    .piece-list {
        justify-content: flex-start;
        gap: 5px;
    }
}

/* === Responsive === */
@media (max-width: 500px) {
    #app { padding: 6px 8px 18px; gap: 8px; }
    .title { font-size: 1.2rem; }
    .btn-action { padding: 8px 12px; font-size: 0.8rem; }
    .btn-icon { width: 34px; height: 34px; }
    .btn-icon svg { width: 17px; height: 17px; }
    .controls { gap: 5px; }
    .piece-list { gap: 5px; }
}

@media (max-width: 380px) {
    #app { padding: 4px 4px 14px; }
    .btn-action { padding: 7px 10px; font-size: 0.76rem; }
    .title { font-size: 1.1rem; }
}

/* === Calendar === */
.calendar-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    margin-bottom: 10px;
}

.cal-nav-btn {
    width: 32px;
    height: 32px;
    border: 1.5px solid var(--border);
    border-radius: 6px;
    background: var(--bg-card);
    color: var(--text);
    cursor: pointer;
    font-size: 0.8rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font);
    padding: 0;
    transition: background 0.12s, transform 0.1s;
}

.cal-nav-btn:hover { background: var(--bg-secondary); }
.cal-nav-btn:active { transform: scale(0.92); }

.cal-month-year {
    font-size: 1rem;
    font-weight: 700;
    color: var(--accent);
    min-width: 140px;
    text-align: center;
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 4px;
    margin: 8px 0 14px;
}

.cal-day-header {
    text-align: center;
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--text-secondary);
    padding: 4px 0 6px;
    border-bottom: 1px solid var(--border);
}

.cal-day {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text);
    cursor: default;
    border: 2px solid transparent;
    transition: background 0.12s, transform 0.1s;
}

.cal-day.completed {
    background: #2ECC71;
    color: #fff;
    cursor: pointer;
    font-weight: 700;
}

.cal-day.completed:hover {
    filter: brightness(1.1);
}

.cal-day.completed:active {
    transform: scale(0.9);
}

.cal-day.today {
    border-color: var(--accent);
}

.cal-day.completed.today {
    border-color: var(--accent);
    box-shadow: 0 0 0 2px var(--accent);
}

.cal-day.other-month {
    color: transparent;
    pointer-events: none;
}

.cal-day:not(.completed):not(.other-month):hover {
    background: var(--bg-secondary);
}

/* === Return to Today Button === */
.btn-return-today {
    padding: 2px 10px;
    border: 1.5px solid var(--accent);
    border-radius: 4px;
    background: transparent;
    color: var(--accent);
    cursor: pointer;
    font-size: 0.7rem;
    font-weight: 600;
    font-family: var(--font);
    transition: background 0.12s, color 0.12s;
    white-space: nowrap;
    margin-left: 8px;
}

.btn-return-today:hover {
    background: var(--accent);
    color: #fff;
}