/* Global Variables and Design System */
:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f8fafc;
    --text-muted: #94a3b8;
    
    /* Harmonious choice colors */
    --color-red: #ef4444;
    --color-red-hover: #f87171;
    --color-red-glow: rgba(239, 68, 68, 0.4);
    
    --color-blue: #3b82f6;
    --color-blue-hover: #60a5fa;
    --color-blue-glow: rgba(59, 130, 246, 0.4);
    
    --color-orange: #f97316;
    --color-orange-hover: #fb923c;
    --color-orange-glow: rgba(249, 115, 22, 0.4);
    
    --color-green: #10b981;
    --color-green-hover: #34d399;
    --color-green-glow: rgba(16, 185, 129, 0.4);

    --color-accent: #8b5cf6; /* Purple */
    --color-correct: #10b981;
    --color-incorrect: #ef4444;
    
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-border: rgba(255, 255, 255, 0.08);
    --card-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    
    --font-family: 'Inter', 'Noto Sans TC', system-ui, -apple-system, sans-serif;
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
    
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset & Base Styles */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow-x: hidden;
    position: relative;
}

/* Background floating decorative circles */
.bg-decorations {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -1;
    pointer-events: none;
}

.bg-decorations::before,
.bg-decorations::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.15;
    animation: float 20s infinite alternate;
}

.bg-decorations::before {
    width: 400px;
    height: 400px;
    background-color: var(--color-blue);
    top: -100px;
    right: -50px;
}

.bg-decorations::after {
    width: 500px;
    height: 500px;
    background-color: var(--color-accent);
    bottom: -150px;
    left: -100px;
    animation-delay: -5s;
}

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

/* App Wrapper */
.app-container {
    width: 100%;
    max-width: 960px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding: 24px;
    position: relative;
    z-index: 10;
}

/* Global Header */
.global-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.game-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, #a78bfa, #60a5fa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo-icon {
    font-size: 1.4rem;
    color: #a78bfa;
    -webkit-text-fill-color: initial;
}

/* Common Card Style (Glassmorphism) */
.card {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    box-shadow: var(--card-shadow);
    padding: 30px;
    transition: var(--transition-normal);
}

.card:hover {
    border-color: rgba(255, 255, 255, 0.15);
}

/* Screen Transitions */
.screen {
    display: none;
    flex-direction: column;
    flex-grow: 1;
    animation: fadeIn var(--transition-normal);
}

.screen.active {
    display: flex;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Buttons System */
button {
    font-family: var(--font-family);
    cursor: pointer;
    border: none;
    outline: none;
    transition: var(--transition-fast);
}

.icon-btn {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border: 1px solid var(--card-border);
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2rem;
}

.icon-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: scale(1.05);
}

.primary-btn {
    background: linear-gradient(135deg, var(--color-accent), #6d28d9);
    color: white;
    font-weight: 700;
    font-size: 1.1rem;
    padding: 14px 32px;
    border-radius: 50px;
    display: inline-flex;
    align-items: center;
    gap: 12px;
    box-shadow: 0 4px 20px rgba(139, 92, 246, 0.4);
}

.primary-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 24px rgba(139, 92, 246, 0.6);
}

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

.secondary-btn {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border: 1px solid var(--card-border);
    font-weight: 600;
    font-size: 1rem;
    padding: 12px 24px;
    border-radius: 50px;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.secondary-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-1px);
}

.pulse {
    animation: pulseGlow 2s infinite;
}

@keyframes pulseGlow {
    0% { box-shadow: 0 0 0 0 rgba(139, 92, 246, 0.7); }
    70% { box-shadow: 0 0 0 15px rgba(139, 92, 246, 0); }
    100% { box-shadow: 0 0 0 0 rgba(139, 92, 246, 0); }
}

/* Welcome Screen Styling */
.welcome-card {
    text-align: center;
    max-width: 600px;
    margin: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.badge {
    background: rgba(139, 92, 246, 0.2);
    border: 1px solid rgba(139, 92, 246, 0.3);
    color: #c084fc;
    padding: 6px 16px;
    border-radius: 50px;
    font-weight: 700;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

h1 {
    font-size: 2.2rem;
    font-weight: 900;
    line-height: 1.3;
}

.highlight {
    background: linear-gradient(135deg, #a78bfa, #3b82f6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle {
    color: var(--text-muted);
    font-size: 1.05rem;
    line-height: 1.6;
}

.welcome-visual {
    width: 100%;
    max-width: 320px;
    margin: 15px 0;
    border-radius: var(--radius-md);
    background: rgba(0, 0, 0, 0.2);
    padding: 10px;
    border: 1px solid rgba(255,255,255,0.05);
}

.preview-svg {
    width: 100%;
    height: auto;
}

.preview-shape {
    fill: rgba(139, 92, 246, 0.15);
    stroke: var(--color-accent);
    stroke-width: 2.5;
}

.preview-base {
    stroke: #ffffff;
    stroke-width: 4.5;
    stroke-linecap: round;
}

.preview-height {
    stroke: var(--color-green);
    stroke-width: 3;
    stroke-dasharray: 4,4;
}

.preview-right-angle {
    fill: none;
    stroke: var(--color-green);
    stroke-width: 1.5;
}

.preview-label {
    fill: var(--text-primary);
    font-size: 12px;
    font-weight: 600;
    text-anchor: middle;
}

.preview-label.h-label {
    fill: var(--color-green);
}

/* Map Screen Styling */
.map-container {
    max-width: 850px;
    margin: auto;
    width: 100%;
}

.screen-title {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 30px;
}

.screen-title h2 {
    font-size: 1.8rem;
    font-weight: 800;
}

.back-btn-small {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border: 1px solid var(--card-border);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1rem;
}

.back-btn-small:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: scale(1.05);
}

.level-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
}

.level-card {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    gap: 16px;
    position: relative;
    overflow: hidden;
}

.level-card::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 60px;
    height: 60px;
    background: radial-gradient(circle, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0) 70%);
    pointer-events: none;
}

.level-number {
    font-size: 0.8rem;
    font-weight: 800;
    color: var(--color-accent);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.level-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
}

.level-card p {
    color: var(--text-muted);
    font-size: 0.9rem;
    line-height: 1.5;
    flex-grow: 1;
}

.level-status {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--card-border);
    padding-top: 12px;
}

.stars {
    display: flex;
    gap: 4px;
    color: #eab308;
    font-size: 0.95rem;
}

.status-text {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 600;
}

.level-play-btn {
    width: 100%;
    padding: 12px;
    border-radius: var(--radius-sm);
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--card-border);
    color: var(--text-primary);
    font-weight: 700;
    margin-top: 10px;
}

.level-card:hover .level-play-btn {
    background: linear-gradient(135deg, var(--color-accent), #6d28d9);
    border-color: transparent;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.3);
}

/* Gameplay Screen Layout */
.game-layout {
    display: grid;
    grid-template-rows: auto 1fr;
    gap: 20px;
    width: 100%;
    flex-grow: 1;
}

.game-status-bar {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 30px;
    padding: 15px 25px;
}

.back-btn {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border: 1px solid var(--card-border);
    font-weight: 600;
    padding: 10px 18px;
    border-radius: 50px;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
}

.back-btn:hover {
    background: rgba(255, 255, 255, 0.15);
}

.game-progress {
    display: flex;
    flex-direction: column;
    gap: 6px;
    width: 100%;
}

.progress-title {
    font-size: 0.9rem;
    font-weight: 700;
    color: #c084fc;
}

.progress-bar-container {
    width: 100%;
    height: 8px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-accent), #3b82f6);
    border-radius: 10px;
    transition: width 0.4s ease;
}

.progress-text {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.score-display {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.1rem;
    font-weight: 700;
}

.star-active {
    color: #eab308;
    animation: pulse 1.5s infinite alternate;
}

/* Main Play Area */
.main-play-area {
    display: grid;
    grid-template-rows: auto 1fr auto;
    gap: 16px;
}

.question-box {
    padding: 18px 25px;
    text-align: center;
}

.question-box h2 {
    font-size: 1.25rem;
    font-weight: 600;
    line-height: 1.5;
}

/* SVG Rendering Container */
.svg-container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    position: relative;
    overflow: hidden;
    min-height: 320px;
}

#gameGeometrySvg {
    width: 100%;
    max-width: 480px;
    height: auto;
    max-height: 350px;
    filter: drop-shadow(0 10px 15px rgba(0, 0, 0, 0.3));
}

.helper-tips {
    position: absolute;
    bottom: 12px;
    left: 20px;
    right: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    color: var(--text-muted);
    background: rgba(15, 23, 42, 0.8);
    padding: 6px 12px;
    border-radius: 50px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    pointer-events: none;
}

.helper-tips i {
    color: #eab308;
}

/* Interactive SVG geometric styles */
.geo-polygon {
    fill: rgba(139, 92, 246, 0.08);
    stroke: rgba(255, 255, 255, 0.25);
    stroke-width: 2.5;
    stroke-linejoin: round;
    transition: all 0.3s ease;
}

.geo-base {
    stroke: #ffffff;
    stroke-width: 6;
    stroke-linecap: round;
    stroke-linejoin: round;
    filter: drop-shadow(0 0 4px rgba(255,255,255,0.4));
}

/* Extension lines for obtuse angles or offsets */
.geo-extension {
    stroke: rgba(255, 255, 255, 0.4);
    stroke-width: 2;
    stroke-dasharray: 4, 4;
}

/* Candidate heights in matching colors */
.geo-height {
    stroke-width: 4;
    stroke-linecap: round;
    stroke-dasharray: 6, 5;
    cursor: pointer;
    transition: stroke-width 0.2s ease, filter 0.2s ease;
}

.geo-height:hover {
    stroke-width: 6;
}

/* Option-specific height strokes */
.geo-height-0 { stroke: var(--color-red); }
.geo-height-1 { stroke: var(--color-blue); }
.geo-height-2 { stroke: var(--color-orange); }
.geo-height-3 { stroke: var(--color-green); }

.geo-height-0.hovered { stroke-width: 7; filter: drop-shadow(0 0 6px var(--color-red-glow)); }
.geo-height-1.hovered { stroke-width: 7; filter: drop-shadow(0 0 6px var(--color-blue-glow)); }
.geo-height-2.hovered { stroke-width: 7; filter: drop-shadow(0 0 6px var(--color-orange-glow)); }
.geo-height-3.hovered { stroke-width: 7; filter: drop-shadow(0 0 6px var(--color-green-glow)); }

/* Right Angle indicator */
.geo-right-angle {
    fill: none;
    stroke-width: 1.5;
    stroke-linejoin: round;
}

.geo-right-angle-0 { stroke: var(--color-red); }
.geo-right-angle-1 { stroke: var(--color-blue); }
.geo-right-angle-2 { stroke: var(--color-orange); }
.geo-right-angle-3 { stroke: var(--color-green); }

/* Choices Container */
.choices-container {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
}

.choice-btn {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 16px 20px;
    border-radius: var(--radius-md);
    background: var(--card-bg);
    border: 1px solid rgba(255,255,255,0.06);
    color: var(--text-primary);
    font-size: 1.05rem;
    font-weight: 700;
    text-align: left;
    transition: var(--transition-normal);
    box-shadow: 0 4px 10px rgba(0,0,0,0.15);
}

.choice-color-indicator {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    flex-shrink: 0;
}

.red-bg { background-color: var(--color-red); }
.blue-bg { background-color: var(--color-blue); }
.orange-bg { background-color: var(--color-orange); }
.green-bg { background-color: var(--color-green); }

/* Choice buttons active / hover states */
.choice-btn:hover {
    transform: translateY(-2px);
}

.choice-btn.color-red:hover { border-color: var(--color-red); box-shadow: 0 6px 20px var(--color-red-glow); background: rgba(239, 68, 68, 0.05); }
.choice-btn.color-blue:hover { border-color: var(--color-blue); box-shadow: 0 6px 20px var(--color-blue-glow); background: rgba(59, 130, 246, 0.05); }
.choice-btn.color-orange:hover { border-color: var(--color-orange); box-shadow: 0 6px 20px var(--color-orange-glow); background: rgba(249, 115, 22, 0.05); }
.choice-btn.color-green:hover { border-color: var(--color-green); box-shadow: 0 6px 20px var(--color-green-glow); background: rgba(16, 185, 129, 0.05); }

/* Modal dialog overlays */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-overlay.active {
    display: flex;
}

.feedback-card {
    max-width: 440px;
    width: calc(100% - 40px);
    text-align: center;
    padding: 35px 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.animate-pop {
    animation: popIn 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes popIn {
    0% { transform: scale(0.8); opacity: 0; }
    100% { transform: scale(1); opacity: 1; }
}

.feedback-icon {
    width: 70px;
    height: 70px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2.2rem;
    margin-bottom: 8px;
}

.feedback-icon.correct {
    background: rgba(16, 185, 129, 0.15);
    color: var(--color-green);
    border: 2px solid var(--color-green);
}

.feedback-icon.incorrect {
    background: rgba(239, 68, 68, 0.15);
    color: var(--color-red);
    border: 2px solid var(--color-red);
}

.explanation-text {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 12px;
}

#feedbackExplanation strong {
    color: var(--text-primary);
}

/* Level complete elements */
.complete-card {
    max-width: 500px;
    margin: auto;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.trophy-container {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    background: rgba(234, 179, 8, 0.1);
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 8px;
}

.trophy-icon {
    font-size: 3.5rem;
    color: #eab308;
    filter: drop-shadow(0 0 10px rgba(234,179,8,0.4));
}

.animate-bounce {
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.final-stars-container {
    display: flex;
    gap: 15px;
    font-size: 2.5rem;
    color: rgba(255, 255, 255, 0.15);
    margin: 10px 0;
}

.final-stars-container .filled {
    color: #eab308;
    filter: drop-shadow(0 0 8px rgba(234,179,8,0.5));
}

.score-summary-details {
    width: 100%;
    background: rgba(0, 0, 0, 0.15);
    border-radius: var(--radius-md);
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    border: 1px solid rgba(255,255,255,0.03);
}

.summary-item {
    display: flex;
    justify-content: space-between;
    font-size: 1rem;
}

.summary-item .label {
    color: var(--text-muted);
}

.summary-item .val {
    font-weight: 700;
}

.complete-actions {
    display: flex;
    gap: 16px;
    width: 100%;
    margin-top: 10px;
}

.complete-actions button {
    flex: 1;
    justify-content: center;
}

/* Responsive adjust */
@media(max-width: 640px) {
    .app-container {
        padding: 16px;
    }
    
    h1 {
        font-size: 1.8rem;
    }
    
    .game-status-bar {
        grid-template-columns: 1fr;
        gap: 15px;
        text-align: center;
    }
    
    .back-btn {
        justify-content: center;
    }
    
    .choices-container {
        grid-template-columns: 1fr;
    }
    
    .complete-actions {
        flex-direction: column;
    }
}