* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.pick-card-mode .flashcard-wrap {
    width: 100%;
    max-width: 320px;
    margin: 0;
}

.image-card-host .flashcard-wrap {
    margin: 0;
    pointer-events: auto;
}

:root {
    --bg-gradient-start: #667eea;
    --bg-gradient-end: #764ba2;
    --primary-color: #667eea;
    --primary-color-dark: #5a67d8;
    --container-bg: #ffffff;
    --surface-bg: #f7fafc;
    --surface-strong: #edf2f7;
    --text-color: #2d3748;
    --text-secondary: #4a5568;
    --text-tertiary: #718096;
    --border-color: #e2e8f0;
    --shadow-color: rgba(31, 41, 55, 0.22);
    --success-color: #16a34a;
    --warning-color: #ea580c;
    --cover-color: rgba(15, 23, 42, 0.9);
}

body.theme-light { --bg-gradient-start: #97B22D; --bg-gradient-end: #89751B; --primary-color: #97B22D; --primary-color-dark: #7d9420; --container-bg: #FEFCAD; --surface-bg: #fff9d6; --surface-strong: #f7efab; --text-color: #2d3748; --text-secondary: #4a5568; --text-tertiary: #5d6b7b; --border-color: #E3DE81; --shadow-color: rgba(73, 59, 11, 0.18); --success-color: #4d7c0f; --warning-color: #c2410c; --cover-color: rgba(61, 52, 14, 0.82); }
body.theme-dark { --bg-gradient-start: #2d3d0f; --bg-gradient-end: #1a2208; --primary-color: #97B22D; --primary-color-dark: #7f9724; --container-bg: #1f2d0a; --surface-bg: #283813; --surface-strong: #31451b; --text-color: #E3DAB2; --text-secondary: #E3DE81; --text-tertiary: #b4c16a; --border-color: #3d4d1f; --shadow-color: rgba(0, 0, 0, 0.35); --success-color: #84cc16; --warning-color: #fb923c; --cover-color: rgba(12, 18, 4, 0.88); }
body.theme-warm-light { --bg-gradient-start: #C6BE28; --bg-gradient-end: #97B22D; --primary-color: #E49A32; --primary-color-dark: #c9801f; --container-bg: #FEFCAD; --surface-bg: #fff5cf; --surface-strong: #faedb6; --text-color: #3d3d1f; --text-secondary: #5d5d3f; --text-tertiary: #7a764d; --border-color: #E3DAB2; --shadow-color: rgba(117, 87, 20, 0.2); --success-color: #65a30d; --warning-color: #d97706; --cover-color: rgba(73, 51, 16, 0.8); }
body.theme-warm-dark { --bg-gradient-start: #2a2510; --bg-gradient-end: #1a1808; --primary-color: #E49A32; --primary-color-dark: #c77f18; --container-bg: #2d2815; --surface-bg: #3a3220; --surface-strong: #463b24; --text-color: #FEFCAD; --text-secondary: #E3DAB2; --text-tertiary: #d4c494; --border-color: #4a3f1a; --shadow-color: rgba(0, 0, 0, 0.35); --success-color: #84cc16; --warning-color: #fb923c; --cover-color: rgba(17, 12, 4, 0.87); }
body.theme-red { --bg-gradient-start: #dc2626; --bg-gradient-end: #991b1b; --primary-color: #ef4444; --primary-color-dark: #dc2626; --container-bg: #ffffff; --surface-bg: #fef2f2; --surface-strong: #fee2e2; --text-color: #1f2937; --text-secondary: #374151; --text-tertiary: #6b7280; --border-color: #fecaca; --shadow-color: rgba(127, 29, 29, 0.24); --success-color: #16a34a; --warning-color: #ea580c; --cover-color: rgba(69, 10, 10, 0.83); }
body.theme-pink { --bg-gradient-start: #ec4899; --bg-gradient-end: #be185d; --primary-color: #f472b6; --primary-color-dark: #ec4899; --container-bg: #ffffff; --surface-bg: #fdf2f8; --surface-strong: #fce7f3; --text-color: #1f2937; --text-secondary: #374151; --text-tertiary: #6b7280; --border-color: #fbcfe8; --shadow-color: rgba(131, 24, 67, 0.24); --success-color: #16a34a; --warning-color: #ea580c; --cover-color: rgba(80, 7, 36, 0.82); }
body.theme-red-dark { --bg-gradient-start: #7f1d1d; --bg-gradient-end: #450a0a; --primary-color: #ef4444; --primary-color-dark: #dc2626; --container-bg: #1a0505; --surface-bg: #450a0a; --surface-strong: #5f1010; --text-color: #fecaca; --text-secondary: #fca5a5; --text-tertiary: #f87171; --border-color: #7f1d1d; --shadow-color: rgba(0, 0, 0, 0.35); --success-color: #4ade80; --warning-color: #fb923c; --cover-color: rgba(15, 3, 3, 0.88); }
body.theme-pink-dark { --bg-gradient-start: #831843; --bg-gradient-end: #500724; --primary-color: #f472b6; --primary-color-dark: #ec4899; --container-bg: #1a050f; --surface-bg: #500724; --surface-strong: #671036; --text-color: #fce7f3; --text-secondary: #fbcfe8; --text-tertiary: #f9a8d4; --border-color: #831843; --shadow-color: rgba(0, 0, 0, 0.35); --success-color: #4ade80; --warning-color: #fdba74; --cover-color: rgba(19, 2, 10, 0.88); }
body.theme-black { --bg-gradient-start: #1f2937; --bg-gradient-end: #111827; --primary-color: #6b7280; --primary-color-dark: #4b5563; --container-bg: #0f172a; --surface-bg: #1e293b; --surface-strong: #273449; --text-color: #f3f4f6; --text-secondary: #d1d5db; --text-tertiary: #9ca3af; --border-color: #374151; --shadow-color: rgba(0, 0, 0, 0.35); --success-color: #4ade80; --warning-color: #fb923c; --cover-color: rgba(2, 6, 23, 0.88); }
body.theme-blue { --bg-gradient-start: #3b82f6; --bg-gradient-end: #1e40af; --primary-color: #60a5fa; --primary-color-dark: #3b82f6; --container-bg: #ffffff; --surface-bg: #eff6ff; --surface-strong: #dbeafe; --text-color: #1f2937; --text-secondary: #374151; --text-tertiary: #6b7280; --border-color: #bfdbfe; --shadow-color: rgba(30, 64, 175, 0.22); --success-color: #16a34a; --warning-color: #ea580c; --cover-color: rgba(8, 47, 73, 0.82); }
body.theme-blue-dark { --bg-gradient-start: #0c4a6e; --bg-gradient-end: #082f49; --primary-color: #38bdf8; --primary-color-dark: #0ea5e9; --container-bg: #0a1929; --surface-bg: #164e63; --surface-strong: #1d6179; --text-color: #e0f2fe; --text-secondary: #7dd3fc; --text-tertiary: #a5f3fc; --border-color: #0e7490; --shadow-color: rgba(0, 0, 0, 0.35); --success-color: #4ade80; --warning-color: #fb923c; --cover-color: rgba(2, 17, 28, 0.86); }

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    min-height: 100vh;
    padding: 20px;
    color: var(--text-color);
}

.container {
    max-width: 760px;
    margin: 0 auto;
    background: var(--container-bg);
    border-radius: 24px;
    padding: 24px;
    box-shadow: 0 20px 60px var(--shadow-color);
}

.header-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 18px;
    gap: 12px;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.header-left h1 {
    font-size: 1.8rem;
}

.app-icon {
    font-size: 2rem;
}

.header-right {
    position: relative;
}

.menu-btn {
    width: 46px;
    height: 46px;
    border-radius: 14px;
    border: 1px solid var(--border-color);
    background: var(--surface-bg);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

.hamburger-icon {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.hamburger-icon span {
    width: 20px;
    height: 2px;
    border-radius: 999px;
    background: var(--text-color);
}

.menu-dropdown {
    position: absolute;
    top: 78px;
    right: 24px;
    width: min(280px, calc(100vw - 48px));
    background: var(--container-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    box-shadow: 0 16px 40px var(--shadow-color);
    padding: 8px;
    z-index: 20;
}

.menu-item,
.menu-item-button {
    width: 100%;
    border: 0;
    background: transparent;
    color: var(--text-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 14px;
    border-radius: 12px;
    cursor: pointer;
    font: inherit;
    text-align: left;
}

.menu-item:hover,
.menu-item-button:hover,
.theme-btn:hover,
.btn:hover,
.upload-btn:hover {
    filter: brightness(0.98);
}

.menu-item:hover,
.menu-item-button:hover {
    background: var(--surface-bg);
}

.menu-icon {
    font-size: 1.1rem;
}

.theme-submenu {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 8px;
    padding: 8px 8px 12px;
}

.theme-btn {
    width: 34px;
    height: 34px;
    border-radius: 999px;
    border: 2px solid rgba(255, 255, 255, 0.85);
    cursor: pointer;
}

.theme-default { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
.theme-black { background: linear-gradient(135deg, #1f2937 0%, #111827 100%); }
.theme-blue { background: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%); }
.theme-blue-dark { background: linear-gradient(135deg, #0c4a6e 0%, #082f49 100%); }
.theme-light { background: linear-gradient(135deg, #97B22D 0%, #89751B 100%); }
.theme-dark { background: linear-gradient(135deg, #2d3d0f 0%, #1a2208 100%); }
.theme-warm-light { background: linear-gradient(135deg, #C6BE28 0%, #97B22D 100%); }
.theme-warm-dark { background: linear-gradient(135deg, #2a2510 0%, #1a1808 100%); }
.theme-red { background: linear-gradient(135deg, #dc2626 0%, #991b1b 100%); }
.theme-red-dark { background: linear-gradient(135deg, #7f1d1d 0%, #450a0a 100%); }
.theme-pink { background: linear-gradient(135deg, #ec4899 0%, #be185d 100%); }
.theme-pink-dark { background: linear-gradient(135deg, #831843 0%, #500724 100%); }

.screen {
    display: none;
}

.screen.active {
    display: block;
}

.status-bar,
.session-strip {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}

.status-bar {
    margin-bottom: 12px;
}

.session-strip {
    margin-bottom: 18px;
}

.session-actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.gameplay-row {
    margin: 12px 0 4px;
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.toggle-option {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: var(--text-secondary);
    font-weight: 600;
    cursor: pointer;
}

.toggle-option input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
}

.status-label {
    font-size: 0.78rem;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 4px;
}

.status-value,
#sessionText,
.image-caption,
.notice,
.results-summary,
.stat-label {
    color: var(--text-secondary);
}

.status-value {
    font-weight: 700;
}

.progress-bar-wrap {
    height: 12px;
    border-radius: 999px;
    overflow: hidden;
    background: var(--surface-strong);
    margin-bottom: 20px;
}

.progress-bar-fill {
    height: 100%;
    width: 0;
    background: linear-gradient(90deg, var(--primary-color) 0%, var(--success-color) 100%);
    transition: width 0.25s ease;
}

.image-section {
    background: var(--surface-bg);
    border: 1px solid var(--border-color);
    border-radius: 18px;
    padding: 16px;
    margin-bottom: 18px;
}

.image-frame {
    position: relative;
    aspect-ratio: 1 / 1;
    width: min(100%, 420px);
    margin: 0 auto;
    overflow: hidden;
    border-radius: 16px;
    background: var(--surface-strong);
}

.reward-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.image-card-host {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
    pointer-events: none;
    z-index: 3;
}

.image-cover {
    position: absolute;
    inset: 0;
    display: grid;
    grid-template-columns: repeat(11, 1fr);
    grid-template-rows: repeat(11, 1fr);
    gap: 1px;
    background: rgba(255, 255, 255, 0.08);
}

.cover-tile {
    background: var(--cover-color);
    transition: opacity 0.25s ease;
}

.cover-tile.pickable {
    cursor: pointer;
    outline: 2px solid rgba(255, 255, 255, 0.35);
    outline-offset: -2px;
}

.cover-tile.pickable:hover {
    background: rgba(15, 23, 42, 0.72);
}

.cover-tile.next-reveal {
    outline: 3px solid #fbbf24;
    outline-offset: -3px;
    box-shadow: inset 0 0 0 1px rgba(255, 244, 180, 0.9);
}

.cover-tile.preview-reveal {
    opacity: 0;
}

.cover-tile.partial {
    opacity: 0.45;
}

.cover-tile.revealed {
    opacity: 0;
}

.image-caption {
    text-align: center;
    font-size: 0.92rem;
    margin-top: 12px;
}

.image-controls {
    margin-top: 14px;
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

.results-image-section {
    margin-bottom: 18px;
}

.results-gameplay-row {
    justify-content: center;
}

.flashcard-host {
    display: flex;
    justify-content: center;
}

.flashcard-wrap {
    perspective: 1200px;
    margin: 18px 0;
    width: min(100%, 420px);
}

.flashcard {
    width: 100%;
    aspect-ratio: 1 / 1;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.5s ease;
    cursor: pointer;
    outline: none;
}

.flashcard-wrap.is-hidden {
    display: none;
}

.flashcard.no-transition {
    transition: none;
}

.flashcard.flipped {
    transform: rotateY(180deg);
}

.card-face {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    border-radius: 20px;
    border: 2px solid var(--border-color);
    background: var(--container-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
}

.card-face-back {
    transform: rotateY(180deg);
    background: var(--surface-bg);
    border-color: var(--primary-color);
}

.card-text {
    font-size: clamp(2rem, 8vw, 4rem);
    font-weight: 800;
    color: var(--text-color);
    text-align: center;
    line-height: 1.1;
    word-break: break-word;
}

.study-actions {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-top: -4px;
}

.rating-row {
    display: flex;
    gap: 12px;
    justify-content: center;
}

.btn,
.upload-btn {
    border: 0;
    border-radius: 14px;
    padding: 12px 18px;
    font: inherit;
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.btn:active,
.upload-btn:active,
.menu-btn:active {
    transform: translateY(1px);
}

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

.btn-secondary {
    background: var(--surface-strong);
    color: var(--text-color);
}

.btn-warning {
    background: rgba(234, 88, 12, 0.14);
    color: var(--warning-color);
}

.btn-success {
    background: rgba(22, 163, 74, 0.14);
    color: var(--success-color);
}

.upload-btn {
    background: var(--primary-color);
    color: #fff;
}

.upload-btn.disabled {
    background: var(--surface-strong);
    color: var(--text-secondary);
    cursor: default;
    pointer-events: none;
}

.notice {
    margin-top: 14px;
    text-align: center;
    min-height: 1.3em;
    font-size: 0.9rem;
}

.results-content {
    text-align: center;
    padding-top: 8px;
}

.results-icon {
    font-size: 3.25rem;
    margin-bottom: 10px;
}

.results-content h2 {
    margin-bottom: 18px;
}

.results-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    margin-bottom: 16px;
}

.stat-box {
    background: var(--surface-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 16px 10px;
}

.stat-value {
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary-color);
}

.results-summary {
    margin-bottom: 18px;
    line-height: 1.6;
}

.results-buckets {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    margin-bottom: 18px;
}

.results-bucket {
    border: 1px solid var(--border-color);
    border-radius: 16px;
    background: var(--surface-bg);
    color: var(--text-color);
    padding: 14px 12px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.results-bucket:disabled {
    opacity: 0.55;
    cursor: default;
}

.results-bucket-count {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary-color);
}

.results-bucket-label {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.results-actions {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.all-time-row {
    margin-top: 18px;
    padding-top: 18px;
    border-top: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 10px;
    align-items: center;
}

.all-time-summary {
    color: var(--text-secondary);
    text-align: center;
    line-height: 1.6;
}

.details-modal {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.55);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    z-index: 50;
}

.details-panel {
    width: min(100%, 560px);
    max-height: 85vh;
    overflow: auto;
    background: var(--container-bg);
    border-radius: 20px;
    padding: 20px;
    box-shadow: 0 24px 60px var(--shadow-color);
}

.details-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    margin-bottom: 8px;
}

.details-subtitle {
    color: var(--text-tertiary);
    margin-bottom: 14px;
}

.details-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.details-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    border: 1px solid var(--border-color);
    background: var(--surface-bg);
    border-radius: 14px;
    padding: 12px 14px;
}

.details-expression {
    font-weight: 700;
}

.details-meta {
    color: var(--text-secondary);
    text-align: right;
    font-size: 0.92rem;
}

@media (max-width: 640px) {
    body {
        padding: 12px;
    }

    .container {
        padding: 18px;
        border-radius: 18px;
    }

    .menu-dropdown {
        top: 68px;
        right: 18px;
    }

    .flashcard {
        width: 100%;
    }

    .rating-row {
        flex-direction: column;
    }

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

    .results-buckets {
        grid-template-columns: 1fr;
    }

    .details-item {
        flex-direction: column;
        align-items: flex-start;
    }

    .details-meta {
        text-align: left;
    }
}