/* MERGE GAME - RESEARCH & SYNTHESIS */
/* Enhanced version with relationships, achievements, and more */

:root {
    --bg-primary: #0a0a1a;
    --bg-secondary: #12122a;
    --bg-card: rgba(30, 30, 60, 0.6);
    --bg-glass: rgba(255, 255, 255, 0.05);
    --level-1: #4ade80;
    --level-1-glow: rgba(74, 222, 128, 0.3);
    --level-2: #60a5fa;
    --level-2-glow: rgba(96, 165, 250, 0.3);
    --level-3: #a78bfa;
    --level-3-glow: rgba(167, 139, 250, 0.3);
    --level-4: #f472b6;
    --level-4-glow: rgba(244, 114, 182, 0.3);
    --level-5: #fbbf24;
    --level-5-glow: rgba(251, 191, 36, 0.4);
    --rel-supports: #4ade80;
    --rel-contrasts: #f87171;
    --rel-extends: #60a5fa;
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-gradient: linear-gradient(135deg, #6366f1, #a855f7, #ec4899);
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --text-muted: rgba(255, 255, 255, 0.4);
    --border-subtle: rgba(255, 255, 255, 0.1);
    --border-active: rgba(255, 255, 255, 0.2);
    --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.5);
    --font-display: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 50%;
    --transition-normal: 250ms ease;
    --transition-slow: 400ms ease;
    --transition-bounce: 400ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

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

html {
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    line-height: 1.6;
}

.app-container {
    position: relative;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.bg-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    overflow: hidden;
    pointer-events: none;
}

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.4;
    animation: float 20s infinite ease-in-out;
}

.orb-1 {
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, var(--accent-primary), transparent);
    top: -200px;
    left: -200px;
}

.orb-2 {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, var(--accent-secondary), transparent);
    top: 50%;
    right: -150px;
    animation-delay: -7s;
}

.orb-3 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, #ec4899, transparent);
    bottom: -100px;
    left: 30%;
    animation-delay: -14s;
}

@keyframes float {
    0%,
    100% {
        transform: translate(0, 0) scale(1);
    }
    50% {
        transform: translate(-30px, 50px) scale(0.95);
    }
}

/* Header */
.main-header {
    position: relative;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 2rem;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-subtle);
    flex-wrap: wrap;
    gap: 1rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-icon {
    font-size: 2rem;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%,
    100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
}

.logo h1 {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 700;
}

.logo .accent {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Topic Selector */
.header-center {
    display: flex;
    align-items: center;
}

.topic-selector-wrapper {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.topic-selector-wrapper label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.topic-selector {
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.topic-selector:hover {
    border-color: var(--accent-primary);
}

.topic-selector:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.header-stats {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
}

.stat-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-muted);
}

.stat-value {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-primary);
}

.progress-bar {
    width: 150px;
    height: 8px;
    background: var(--bg-secondary);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: var(--accent-gradient);
    border-radius: var(--radius-full);
    transition: width var(--transition-slow);
}

.header-buttons {
    display: flex;
    gap: 0.75rem;
}

.btn-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: var(--bg-glass);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 1.25rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-icon:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    transform: translateY(-2px);
}

.btn-reset {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1.5rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-reset:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    transform: translateY(-2px);
}

.btn-help {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1.5rem;
    background: var(--bg-glass);
    border: 1px solid var(--accent-primary);
    border-radius: var(--radius-md);
    color: var(--accent-primary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-help:hover {
    background: rgba(99, 102, 241, 0.2);
    box-shadow: 0 0 15px rgba(99, 102, 241, 0.3);
    transform: translateY(-2px);
}

/* Game Container */
.game-container {
    position: relative;
    z-index: 5;
    flex: 1;
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2rem;
    padding: 2rem;
    max-width: 1600px;
    margin: 0 auto;
    width: 100%;
}

/* Level Ladder */
.level-ladder {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 1.5rem;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
    gap: 0;
    height: fit-content;
}

.level-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem 1rem;
    width: 100%;
    background: var(--bg-glass);
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    transition: all var(--transition-normal);
    opacity: 0.5;
}

.level-item.active {
    opacity: 1;
}

.level-item.completed {
    opacity: 1;
    background: rgba(74, 222, 128, 0.1);
}

.level-item[data-level="1"].active {
    border-color: var(--level-1);
    box-shadow: 0 0 20px var(--level-1-glow);
}

.level-item[data-level="2"].active {
    border-color: var(--level-2);
    box-shadow: 0 0 20px var(--level-2-glow);
}

.level-item[data-level="3"].active {
    border-color: var(--level-3);
    box-shadow: 0 0 20px var(--level-3-glow);
}

.level-item[data-level="4"].active {
    border-color: var(--level-4);
    box-shadow: 0 0 20px var(--level-4-glow);
}

.level-item[data-level="5"].active {
    border-color: var(--level-5);
    box-shadow: 0 0 20px var(--level-5-glow);
}

.level-badge {
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border-radius: var(--radius-full);
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 0.85rem;
}

.level-name {
    flex: 1;
    font-size: 0.8rem;
    font-weight: 500;
}

.level-emoji {
    font-size: 1.1rem;
}

.level-connector {
    width: 2px;
    height: 16px;
    background: linear-gradient(to bottom, var(--border-subtle), transparent);
    margin: 0.15rem 0;
}

/* Compatibility Hints */
.compatibility-hints {
    width: 100%;
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-subtle);
}

.compatibility-hints h4 {
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.hint-empty {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-align: center;
}

.hint-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    padding: 0.75rem;
    background: var(--bg-card);
    border-radius: var(--radius-md);
    margin-bottom: 0.5rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.hint-item:hover {
    background: rgba(99, 102, 241, 0.2);
    transform: translateX(4px);
}

.hint-rel {
    font-size: 0.75rem;
    font-weight: 600;
}

.hint-desc {
    font-size: 0.7rem;
    color: var(--text-muted);
}

/* Achievements Panel */
.achievements-panel {
    width: 100%;
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-subtle);
}

.achievements-panel h4 {
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.achievements-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    max-height: 200px;
    overflow-y: auto;
}

.achievement-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem;
    background: var(--bg-card);
    border-radius: var(--radius-sm);
    transition: all var(--transition-normal);
}

.achievement-item.locked {
    opacity: 0.5;
}

.achievement-item.unlocked {
    background: rgba(74, 222, 128, 0.1);
    border: 1px solid rgba(74, 222, 128, 0.3);
}

.achievement-emoji {
    font-size: 1.25rem;
}

.achievement-details {
    display: flex;
    flex-direction: column;
}

.achievement-details strong {
    font-size: 0.75rem;
    font-weight: 600;
}

.achievement-details span {
    font-size: 0.65rem;
    color: var(--text-muted);
}

/* Achievement Notification */
.achievement-notification {
    position: fixed;
    top: 100px;
    right: -300px;
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.5rem;
    background: linear-gradient(135deg, rgba(74, 222, 128, 0.2), rgba(74, 222, 128, 0.1));
    border: 1px solid var(--level-1);
    border-radius: var(--radius-lg);
    box-shadow: 0 8px 32px rgba(74, 222, 128, 0.3);
    z-index: 1000;
    transition: right var(--transition-slow);
}

.achievement-notification.visible {
    right: 2rem;
}

.achievement-notification .achievement-emoji {
    font-size: 2rem;
}

.achievement-notification .achievement-info {
    display: flex;
    flex-direction: column;
}

.achievement-notification .achievement-info strong {
    color: var(--level-1);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.achievement-notification .achievement-info span {
    font-size: 1rem;
    font-weight: 600;
}

/* Game Board */
.game-board {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    padding: 2rem;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
}

.board-header {
    text-align: center;
}

.board-header h2 {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.board-header p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.btn-add-citation {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--bg-glass);
    border: 1px dashed var(--accent-primary);
    border-radius: var(--radius-md);
    color: var(--accent-primary);
    font-family: var(--font-body);
    font-size: 0.85rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-add-citation:hover {
    background: rgba(99, 102, 241, 0.2);
    border-style: solid;
}

.btn-add-citation span {
    font-size: 1.1rem;
    font-weight: 700;
}

/* Cards Container */
.cards-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    min-height: 200px;
    padding: 1rem;
}

/* Research Cards */
.research-card {
    position: relative;
    padding: 1.25rem;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border: 2px solid var(--border-subtle);
    cursor: grab;
    transition: all var(--transition-normal);
    user-select: none;
}

.research-card:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: var(--shadow-lg);
}

.research-card:active {
    cursor: grabbing;
    transform: scale(0.98);
}

.research-card.dragging {
    opacity: 0.5;
    transform: scale(0.95);
}

/* Connection Highlights */
.research-card.connection-highlight {
    transform: translateY(-4px);
    animation: highlightPulse 1s ease infinite;
}

.research-card.rel-supports {
    border-color: var(--rel-supports);
    box-shadow: 0 0 20px rgba(74, 222, 128, 0.4);
}

.research-card.rel-contrasts {
    border-color: var(--rel-contrasts);
    box-shadow: 0 0 20px rgba(248, 113, 113, 0.4);
}

.research-card.rel-extends {
    border-color: var(--rel-extends);
    box-shadow: 0 0 20px rgba(96, 165, 250, 0.4);
}

@keyframes highlightPulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.8;
    }
}

.research-card.level-1 {
    border-color: var(--level-1);
    box-shadow: 0 4px 20px var(--level-1-glow);
}

.research-card.level-2 {
    border-color: var(--level-2);
    box-shadow: 0 4px 20px var(--level-2-glow);
}

.research-card.level-3 {
    border-color: var(--level-3);
    box-shadow: 0 4px 20px var(--level-3-glow);
}

.research-card.level-4 {
    border-color: var(--level-4);
    box-shadow: 0 4px 20px var(--level-4-glow);
}

.research-card.level-5 {
    border-color: var(--level-5);
    box-shadow: 0 4px 20px var(--level-5-glow);
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.1), rgba(245, 158, 11, 0.1));
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 0.75rem;
}

.card-level {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.25rem 0.5rem;
    background: var(--bg-glass);
    border-radius: var(--radius-sm);
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.card-level.level-1 { color: var(--level-1); }
.card-level.level-2 { color: var(--level-2); }
.card-level.level-3 { color: var(--level-3); }
.card-level.level-4 { color: var(--level-4); }
.card-level.level-5 { color: var(--level-5); }

.card-type {
    font-size: 1.1rem;
}

.card-content {
    font-size: 0.85rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

.card-content strong {
    color: var(--text-primary);
}

.card-source {
    margin-top: 0.75rem;
    padding-top: 0.5rem;
    border-top: 1px solid var(--border-subtle);
    font-size: 0.7rem;
    color: var(--text-muted);
    font-style: italic;
}

/* Card Tags */
.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    margin-top: 0.75rem;
}

.tag {
    padding: 0.15rem 0.5rem;
    background: var(--bg-glass);
    border-radius: var(--radius-sm);
    font-size: 0.65rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Card Relationships */
.card-relationships {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
}

.connection-count {
    font-size: 0.7rem;
    color: var(--text-muted);
    background: var(--bg-glass);
    padding: 0.2rem 0.5rem;
    border-radius: var(--radius-sm);
}

/* Relationship Indicator */
.relationship-indicator {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    margin-bottom: 1rem;
    animation: fadeIn 0.3s ease;
}

.relationship-indicator.visible {
    display: flex;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.rel-badge {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    border: 1px solid;
}

.rel-emoji {
    font-size: 1.25rem;
}

.rel-label {
    font-weight: 600;
    font-size: 0.9rem;
}

.rel-desc {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-align: center;
}

/* Merge Zone */
.merge-zone {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    padding: 2rem;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(139, 92, 246, 0.1));
    border-radius: var(--radius-xl);
    border: 2px dashed var(--border-active);
    margin-top: 1rem;
}

.merge-slot {
    width: 200px;
    height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-glass);
    border-radius: var(--radius-lg);
    border: 2px dashed var(--border-subtle);
    transition: all var(--transition-normal);
    overflow: hidden;
}

.merge-slot.drag-over {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.2);
    transform: scale(1.05);
}

.merge-slot.filled {
    border-style: solid;
    border-color: var(--accent-primary);
}

.slot-label {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.merge-slot .research-card {
    width: 100%;
    height: 100%;
    margin: 0;
    font-size: 0.7rem;
    padding: 0.6rem;
}

.merge-slot .card-content {
    overflow: hidden;
    text-overflow: ellipsis;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    font-size: 0.7rem;
}

.merge-icon {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border-radius: var(--radius-full);
    font-size: 1.5rem;
    font-weight: 700;
    animation: pulse 2s infinite;
}

.merge-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-lg);
    color: white;
    font-family: var(--font-display);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

.merge-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.merge-btn:not(:disabled):hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.5);
}

.merge-btn.error {
    background: linear-gradient(135deg, #f87171, #ef4444);
}

/* Preview Panel */
.preview-panel {
    display: none;
    flex-direction: column;
    gap: 0.75rem;
    padding: 1.25rem;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-subtle);
    margin-top: 1rem;
    animation: fadeIn 0.3s ease;
}

.preview-panel.visible {
    display: flex;
}

.preview-panel h4 {
    font-size: 0.85rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.preview-content {
    padding: 1rem;
    background: var(--bg-glass);
    border-radius: var(--radius-md);
}

.preview-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.preview-level {
    padding: 0.25rem 0.5rem;
    background: var(--bg-card);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
}

.preview-type {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.preview-text {
    font-size: 0.8rem;
    color: var(--text-muted);
    line-height: 1.5;
}

/* Paper Builder Sidebar */
.paper-builder {
    position: fixed;
    top: 80px;
    right: -400px;
    width: 380px;
    max-height: calc(100vh - 100px);
    background: var(--bg-secondary);
    border-radius: var(--radius-xl) 0 0 var(--radius-xl);
    border: 1px solid var(--border-subtle);
    border-right: none;
    z-index: 50;
    transition: right var(--transition-slow);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.paper-builder.visible {
    right: 0;
}

.paper-builder-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.25rem;
    border-bottom: 1px solid var(--border-subtle);
}

.paper-builder-header h3 {
    font-family: var(--font-display);
    font-size: 1.1rem;
}

.btn-close-paper {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-glass);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 1.25rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-close-paper:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
}

.paper-content {
    flex: 1;
    padding: 1.25rem;
    overflow-y: auto;
}

.paper-empty {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
    padding: 2rem;
}

.paper-structure {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.paper-section {
    padding: 1rem;
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border-left: 3px solid;
}

.paper-section.level-2 { border-color: var(--level-2); }
.paper-section.level-3 { border-color: var(--level-3); }
.paper-section.level-4 { border-color: var(--level-4); }
.paper-section.level-5 { border-color: var(--level-5); }

.paper-section h4 {
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.paper-part {
    padding: 0.75rem;
    background: var(--bg-glass);
    border-radius: var(--radius-sm);
    margin-bottom: 0.5rem;
}

.paper-part:last-child {
    margin-bottom: 0;
}

.paper-part p {
    font-size: 0.8rem;
    color: var(--text-muted);
    line-height: 1.5;
}

/* Result Panel */
.result-panel {
    display: none;
    flex-direction: column;
    gap: 1.5rem;
    padding: 2rem;
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.1), rgba(245, 158, 11, 0.1));
    border-radius: var(--radius-xl);
    border: 2px solid var(--level-5);
    box-shadow: 0 0 40px var(--level-5-glow);
    margin-top: 1.5rem;
}

.result-panel.visible {
    display: flex;
    animation: slideUp 0.5s ease;
}

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

.result-header h3 {
    font-family: var(--font-display);
    font-size: 1.5rem;
    color: var(--level-5);
    text-align: center;
}

.result-content {
    padding: 1.5rem;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    line-height: 1.8;
    text-align: center;
}

.btn-celebrate {
    align-self: center;
    padding: 1rem 2rem;
    background: linear-gradient(135deg, var(--level-5), #f59e0b);
    border: none;
    border-radius: var(--radius-lg);
    color: var(--bg-primary);
    font-family: var(--font-display);
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-celebrate:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 30px var(--level-5-glow);
}

/* Modals */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    transition: opacity var(--transition-normal);
}

.modal-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.custom-citation-modal,
.workshop-modal {
    opacity: 0;
    pointer-events: none;
}

.custom-citation-modal.visible,
.workshop-modal.visible {
    opacity: 1;
    pointer-events: all;
}

.modal-content {
    max-width: 500px;
    width: 90%;
    padding: 2rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
    animation: modalSlide 0.4s ease;
}

.instructions-modal {
    max-width: 550px;
    max-height: 90vh;
    overflow-y: auto;
}

@keyframes modalSlide {
    from {
        opacity: 0;
        transform: translateY(-30px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-header {
    margin-bottom: 1.5rem;
    position: relative;
}

.modal-header h2 {
    font-family: var(--font-display);
    font-size: 1.5rem;
    text-align: center;
}

.modal-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 0.5rem;
}

.btn-close-modal {
    position: absolute;
    top: 0;
    right: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-glass);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 1.25rem;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-close-modal:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
}

/* Instruction Steps */
.instruction-step {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

.step-number {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border-radius: var(--radius-full);
    font-family: var(--font-display);
    font-weight: 700;
    flex-shrink: 0;
}

.step-content h4 {
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.step-content p {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Instruction Tips */
.instruction-tips {
    margin-top: 1.5rem;
    padding: 1rem;
    background: var(--bg-glass);
    border-radius: var(--radius-md);
}

.instruction-tips h4 {
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.instruction-tips ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.instruction-tips li {
    font-size: 0.8rem;
    color: var(--text-muted);
    padding-left: 1rem;
    position: relative;
}

.instruction-tips li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--accent-primary);
}

.btn-start {
    width: 100%;
    padding: 1rem 2rem;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-lg);
    color: white;
    font-family: var(--font-display);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    margin-top: 1.5rem;
}

.btn-start:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.4);
}

/* Custom Citation Form */
.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.form-group textarea,
.form-group input {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 0.9rem;
    transition: all var(--transition-normal);
}

.form-group textarea {
    min-height: 100px;
    resize: vertical;
}

.form-group textarea:focus,
.form-group input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.form-group textarea::placeholder,
.form-group input::placeholder {
    color: var(--text-muted);
}

.btn-submit-citation {
    width: 100%;
    padding: 1rem 2rem;
    background: var(--level-1);
    border: none;
    border-radius: var(--radius-lg);
    color: var(--bg-primary);
    font-family: var(--font-display);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-submit-citation:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px var(--level-1-glow);
}

/* Victory Modal */
.victory-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.9);
    backdrop-filter: blur(20px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 200;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-slow);
}

.victory-modal.visible {
    opacity: 1;
    pointer-events: all;
}

.victory-content {
    text-align: center;
    padding: 3rem;
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.2), rgba(245, 158, 11, 0.1));
    border-radius: var(--radius-xl);
    border: 2px solid var(--level-5);
    box-shadow: 0 0 60px var(--level-5-glow);
    animation: victoryPop 0.6s var(--transition-bounce);
}

@keyframes victoryPop {
    from {
        transform: scale(0.5);
    }
    to {
        transform: scale(1);
    }
}

.victory-stars {
    font-size: 2rem;
    margin-bottom: 1rem;
    animation: twinkle 1s infinite alternate;
}

@keyframes twinkle {
    from {
        opacity: 0.7;
    }
    to {
        opacity: 1;
    }
}

.victory-content h2 {
    font-family: var(--font-display);
    font-size: 2rem;
    color: var(--level-5);
    margin-bottom: 0.75rem;
}

.victory-content p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.victory-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
}

.victory-stat-value {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--level-5);
    display: block;
}

.victory-stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* Victory Achievements */
.victory-achievements {
    margin-bottom: 1.5rem;
    padding: 1rem;
    background: var(--bg-glass);
    border-radius: var(--radius-md);
}

.victory-achievements h4 {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.achievement-icons {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    font-size: 1.5rem;
}

.btn-play-again {
    padding: 1rem 3rem;
    background: linear-gradient(135deg, var(--level-5), #f59e0b);
    border: none;
    border-radius: var(--radius-lg);
    color: var(--bg-primary);
    font-family: var(--font-display);
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.btn-play-again:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 30px var(--level-5-glow);
}

/* Merge Animation */
.merge-animation-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(5px);
    z-index: 150;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-normal);
}

.merge-animation-overlay.active {
    opacity: 1;
    pointer-events: all;
}

.particle {
    position: absolute;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    animation: particleExplode 1s ease-out forwards;
}

@keyframes particleExplode {
    0% {
        transform: translate(0, 0) scale(1);
        opacity: 1;
    }
    100% {
        transform: translate(var(--tx), var(--ty)) scale(0);
        opacity: 0;
    }
}

.merge-result-preview {
    padding: 2rem 3rem;
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    border: 2px solid var(--accent-primary);
    box-shadow: 0 0 60px rgba(99, 102, 241, 0.5);
    max-width: 400px;
    text-align: center;
    animation: resultPop 0.5s var(--transition-bounce);
}

@keyframes resultPop {
    from {
        transform: scale(0);
    }
    to {
        transform: scale(1);
    }
}

.merge-result-preview h3 {
    font-family: var(--font-display);
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--accent-primary);
}

.merge-result-preview p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.merge-rel-note {
    margin-top: 0.5rem;
    font-weight: 600;
}

/* Responsive Styles */
@media (max-width: 1024px) {
    .game-container {
        grid-template-columns: 1fr;
    }

    .level-ladder {
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: center;
    }

    .level-connector {
        width: 20px;
        height: 2px;
    }

    .level-item {
        width: auto;
        flex: 0 0 auto;
    }

    .compatibility-hints,
    .achievements-panel {
        display: none;
    }

    .paper-builder {
        width: 100%;
        max-width: 400px;
        border-radius: var(--radius-xl);
    }
}

@media (max-width: 768px) {
    .main-header {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }

    .header-center {
        order: -1;
        width: 100%;
    }

    .topic-selector-wrapper {
        flex-direction: column;
        width: 100%;
    }

    .topic-selector {
        width: 100%;
    }

    .header-stats {
        width: 100%;
        justify-content: space-around;
    }

    .merge-zone {
        flex-direction: column;
    }

    .merge-slot {
        width: 100%;
        max-width: 280px;
    }

    .merge-icon {
        transform: rotate(90deg);
    }

    .cards-container {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .level-ladder {
        display: none;
    }

    .game-board {
        padding: 1rem;
    }

    .modal-content {
        margin: 1rem;
        padding: 1.5rem;
    }

    .board-header h2 {
        font-size: 1.25rem;
    }

    .victory-content {
        padding: 2rem 1.5rem;
    }

    .victory-content h2 {
        font-size: 1.5rem;
    }

    .paper-builder {
        top: 60px;
        max-height: calc(100vh - 80px);
    }
}