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

:root {
    /* Light mode colors */
    --bg-primary: #f5f7fa;
    --bg-secondary: #c3cfe2;
    --bg-card: white;
    --text-primary: #333;
    --text-secondary: #6c757d;
    --accent-primary: #667eea;
    --accent-secondary: #764ba2;
    --border-color: #e9ecef;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --progress-bg: #e9ecef;
    --button-bg: #f8f9fa;
    --button-hover: #667eea;
    --success-bg: #d4edda;
    --success-text: #155724;
    --error-bg: #f8d7da;
    --error-text: #721c24;
    --shadow-light: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 5px 20px rgba(0, 0, 0, 0.15);
    --shadow-heavy: 0 10px 30px rgba(0, 0, 0, 0.2);
    --transition-fast: 0.2s ease;
    --transition-medium: 0.3s ease;
    --transition-slow: 0.5s ease;
}

[data-theme="dark"] {
    /* Dark mode colors */
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-card: #333;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --accent-primary: #8b9dc3;
    --accent-secondary: #a78bfa;
    --border-color: #555;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --progress-bg: #555;
    --button-bg: #444;
    --button-hover: #8b9dc3;
    --success-bg: #2d5a2d;
    --success-text: #90ee90;
    --error-bg: #5a2d2d;
    --error-text: #ff6b6b;
    --shadow-light: 0 2px 10px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 5px 20px rgba(0, 0, 0, 0.4);
    --shadow-heavy: 0 10px 30px rgba(0, 0, 0, 0.5);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    min-height: 100vh;
    color: var(--text-primary);
    transition: all var(--transition-medium);
    overflow-x: hidden;
}

/* Smooth scroll behavior */
html {
    scroll-behavior: smooth;
}

/* Header Styles */
.header {
    background: var(--bg-card);
    box-shadow: var(--shadow-light);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: all var(--transition-medium);
}

.header:hover {
    box-shadow: var(--shadow-medium);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: transform var(--transition-medium);
}

.logo-container:hover {
    transform: scale(1.05);
}

.croissant-img {
    width: 50px;
    height: 50px;
    object-fit: contain;
    animation: bounce 2s infinite;
    transition: transform var(--transition-fast);
}

.croissant-img:hover {
    transform: rotate(10deg) scale(1.1);
}

.app-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin: 0;
    transition: color var(--transition-fast);
}

.logo-container:hover .app-title {
    color: var(--accent-secondary);
}

.nav-menu {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.nav-btn {
    background: var(--button-bg);
    border: 2px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.75rem 1.5rem;
    border-radius: 25px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all var(--transition-medium);
    position: relative;
    overflow: hidden;
}

.nav-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left var(--transition-slow);
}

.nav-btn:hover::before {
    left: 100%;
}

.nav-btn:hover {
    background: var(--button-hover);
    color: white;
    border-color: var(--accent-primary);
    transform: translateY(-3px);
    box-shadow: var(--shadow-medium);
}

.nav-btn.active {
    background: var(--accent-primary);
    color: white;
    border-color: var(--accent-primary);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
    transform: translateY(-2px);
}

/* Theme Toggle Button */
.theme-toggle {
    background: none;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
    transition: all var(--transition-medium);
    color: var(--text-primary);
}

.theme-toggle:hover {
    background-color: var(--hover-bg);
    transform: scale(1.1);
    box-shadow: var(--shadow-light);
}

/* Donation Button */
.donate-btn {
    background: none;
    border: none;
    font-size: 0.9rem;
    cursor: pointer;
    padding: 8px 12px;
    border-radius: 20px;
    transition: all var(--transition-medium);
    color: var(--text-primary);
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    gap: 6px;
    font-weight: 600;
    border: 1px solid transparent;
}

.donate-btn:hover {
    background: linear-gradient(135deg, #ff6b6b, #ffa500);
    transform: scale(1.05);
    box-shadow: var(--shadow-medium);
    color: white;
    border-color: transparent;
}

.donate-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.5s;
}

.donate-btn:hover::before {
    left: 100%;
}

.donate-btn:active {
    transform: scale(0.95);
}

/* Dark mode adjustments for donation button */
[data-theme="dark"] .donate-btn:hover {
    background: linear-gradient(135deg, #ff8a80, #ffb74d);
    box-shadow: 0 0 20px rgba(255, 107, 107, 0.4);
}

/* Donation Invitation */
.donation-invitation {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--card-bg);
    border: 2px solid var(--accent-primary);
    border-radius: 16px;
    padding: 20px;
    box-shadow: var(--shadow-heavy);
    backdrop-filter: blur(10px);
    animation: slideUp 0.5s ease-out;
    z-index: 1000;
    max-width: 300px;
    text-align: center;
}

.donation-content p {
    margin: 0 0 15px 0;
    color: var(--text-primary);
    font-size: 0.95rem;
    line-height: 1.4;
}

.donation-link-btn {
    background: linear-gradient(135deg, #ff6b6b, #ffa500);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 25px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-medium);
    margin-right: 10px;
    box-shadow: var(--shadow-light);
}

.donation-link-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
    background: linear-gradient(135deg, #ff5252, #ff9800);
}

.donation-close-btn {
    background: var(--button-bg);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 10px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-medium);
}

.donation-close-btn:hover {
    background: var(--button-hover);
    color: var(--text-primary);
}

/* Main Content */
.main-content {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 2rem;
    animation: slideInUp 0.6s ease;
}

.game-container {
    display: none;
    background: var(--bg-card);
    border-radius: 20px;
    padding: 2rem;
    box-shadow: var(--shadow-heavy);
    animation: fadeInScale 0.5s ease;
    border: 1px solid var(--border-color);
    transition: all var(--transition-medium);
    position: relative;
    overflow: hidden;
}

.game-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: left var(--transition-slow);
}

.game-container:hover::before {
    left: 100%;
}

.game-container.active {
    display: block;
    animation: slideInUp 0.6s ease;
}

.game-container:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px var(--shadow-color);
}

.quiz-header {
    text-align: center;
    margin-bottom: 2rem;
    animation: fadeInDown 0.8s ease;
}

.verb-info h2 {
    color: var(--accent-primary);
    font-size: 2rem;
    margin-bottom: 0.5rem;
    transition: color var(--transition-fast);
    animation: pulse 2s infinite;
}

.verb-info h2:hover {
    color: var(--accent-secondary);
}

.verb-info span {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-right: 1rem;
    transition: color var(--transition-fast);
}

/* Progress Bar */
.progress-container {
    margin-bottom: 2rem;
    text-align: center;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.progress-bar {
    background: var(--progress-bg);
    border-radius: 25px;
    height: 20px;
    overflow: hidden;
    margin-bottom: 0.5rem;
    position: relative;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
    transition: all var(--transition-medium);
}

.progress-bar:hover {
    transform: scale(1.02);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
}

.progress-fill {
    background: linear-gradient(90deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    height: 100%;
    border-radius: 25px;
    transition: width var(--transition-slow) cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.progress-fill::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent 0%, rgba(255, 255, 255, 0.3) 50%, transparent 100%);
    animation: shimmer 2s infinite;
}

.progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent 0%, rgba(255, 255, 255, 0.1) 50%, transparent 100%);
    animation: shimmer 3s infinite reverse;
}

.progress-text {
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 0.9rem;
    transition: all var(--transition-fast);
    animation: fadeIn 0.8s ease 0.4s both;
}

.progress-text:hover {
    color: var(--accent-primary);
    transform: scale(1.1);
}

/* Quiz Content */
.quiz-content {
    text-align: center;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.sentence-text {
    font-size: 1.3rem;
    color: var(--text-primary);
    margin-bottom: 2rem;
    line-height: 1.6;
    transition: all var(--transition-medium);
    padding: 1.5rem;
    background: var(--button-bg);
    border-radius: 15px;
    border: 2px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.sentence-text::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: left var(--transition-slow);
}

.sentence-text:hover::before {
    left: 100%;
}

.sentence-text:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
    border-color: var(--accent-primary);
}

.options-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-top: 1rem;
    animation: fadeInUp 0.8s ease 0.6s both;
}

.option-btn {
    background: var(--bg-card);
    border: 2px solid var(--border-color);
    color: var(--text-primary);
    padding: 1rem 1.5rem;
    border-radius: 15px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all var(--transition-medium);
    min-height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-light);
}

.option-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left var(--transition-slow);
}

.option-btn:hover::before {
    left: 100%;
}

.option-btn:hover:not(.disabled) {
    border-color: var(--accent-primary);
    background: var(--button-bg);
    transform: translateY(-5px) scale(1.02);
    box-shadow: var(--shadow-heavy);
}

.option-btn.correct {
    background: var(--success-bg);
    border-color: var(--success-text);
    color: var(--success-text);
    animation: correctPulse 0.6s ease;
    transform: scale(1.05);
}

.option-btn.incorrect {
    background: var(--error-bg);
    border-color: var(--error-text);
    color: var(--error-text);
    animation: incorrectShake 0.6s ease;
}

.option-btn.disabled {
    cursor: not-allowed;
    opacity: 0.7;
    transform: scale(0.98);
}

/* Celebration Modal */
.celebration {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    animation: fadeIn var(--transition-medium) ease;
    backdrop-filter: blur(5px);
}

.celebration.hidden {
    display: none;
}

.celebration-content {
    background: var(--bg-card);
    padding: 3rem;
    border-radius: 20px;
    text-align: center;
    max-width: 500px;
    margin: 2rem;
    animation: celebrationPop 0.6s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    box-shadow: var(--shadow-heavy);
    border: 2px solid var(--accent-primary);
    position: relative;
    overflow: hidden;
}

.celebration-content::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, transparent 30%, rgba(102, 126, 234, 0.1) 50%, transparent 70%);
    animation: celebrationShine 2s infinite;
}

.celebration-content h2 {
    color: var(--accent-primary);
    margin-bottom: 1rem;
    font-size: 2rem;
    animation: celebrationText 0.8s ease 0.3s both;
}

.celebration-content p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 1.1rem;
    animation: celebrationText 0.8s ease 0.5s both;
}

.croissant-animation {
    font-size: 4rem;
    animation: dance 2s infinite;
    margin-bottom: 2rem;
    animation: celebrationDance 1s ease 0.7s both, dance 2s infinite 1.7s;
}

.next-verb-btn {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: 600;
    transition: all var(--transition-medium);
    box-shadow: var(--shadow-medium);
    position: relative;
    overflow: hidden;
    animation: celebrationText 0.8s ease 0.9s both;
}

.next-verb-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left var(--transition-slow);
}

.next-verb-btn:hover::before {
    left: 100%;
}

.next-verb-btn:hover {
    transform: translateY(-5px) scale(1.05);
    box-shadow: 0 15px 35px rgba(102, 126, 234, 0.4);
}

/* Enhanced Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInScale {
    from { 
        opacity: 0; 
        transform: scale(0.9);
    }
    to { 
        opacity: 1; 
        transform: scale(1);
    }
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

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

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateX(-50%) translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
}

@keyframes dance {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    25% { transform: translateY(-10px) rotate(5deg); }
    50% { transform: translateY(-5px) rotate(-5deg); }
    75% { transform: translateY(-10px) rotate(5deg); }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-10px); }
    60% { transform: translateY(-5px); }
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes correctPulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1.05); }
}

@keyframes incorrectShake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

@keyframes celebrationPop {
    0% { 
        opacity: 0; 
        transform: scale(0.3) rotate(-10deg);
    }
    50% { 
        transform: scale(1.1) rotate(5deg);
    }
    100% { 
        opacity: 1; 
        transform: scale(1) rotate(0deg);
    }
}

@keyframes celebrationShine {
    0% { transform: translateX(-100%) translateY(-100%); }
    100% { transform: translateX(100%) translateY(100%); }
}

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

@keyframes celebrationDance {
    0% { 
        opacity: 0; 
        transform: scale(0) rotate(180deg);
    }
    100% { 
        opacity: 1; 
        transform: scale(1) rotate(0deg);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
        padding: 0 1rem;
    }
    
    .nav-menu {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
        gap: 0.5rem;
    }
    
    .donate-btn {
        font-size: 0.8rem;
        padding: 6px 10px;
        gap: 4px;
    }
    
    .main-content {
        padding: 0 1rem;
        margin: 1rem auto;
    }
    
    .game-container {
        padding: 1.5rem;
    }
    
    .options-container {
        grid-template-columns: 1fr;
    }
    
    .celebration-content {
        padding: 2rem;
        margin: 1rem;
    }
    
    .next-verb-btn {
        padding: 0.8rem 1.5rem;
        font-size: 1rem;
    }
    
    .verb-info h2 {
        font-size: 1.5rem;
    }
    
    .sentence-text {
        font-size: 1.1rem;
    }
    
    .croissant-img {
        width: 40px;
        height: 40px;
    }
} 

/* Dark mode adjustments for donation invitation */
[data-theme="dark"] .donation-invitation {
    background: var(--card-bg);
    border-color: var(--accent-secondary);
}

[data-theme="dark"] .donation-link-btn {
    background: linear-gradient(135deg, #ff8a80, #ffb74d);
}

[data-theme="dark"] .donation-link-btn:hover {
    background: linear-gradient(135deg, #ff7043, #ffcc02);
}