:root {
    --primary-color: #4a90e2;
    --success-color: #2ecc71;
    --error-color: #e74c3c;
    --background-color: #f8f9fa;
    --card-background: #ffffff;
    --text-color: #2c3e50;
    --border-radius: 12px;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

body {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: var(--background-color);
    font-family: 'Poppins', sans-serif;
    color: var(--text-color);
    transition: var(--transition);
    padding: 20px;
}

.container {
    background-color: var(--card-background);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    padding: 2rem;
    width: 90%;
    max-width: 800px;
    position: relative;
}

#letter {
    font-size: 8rem;
    color: var(--text-color);
    text-align: center;
    margin: 2rem 0;
    transition: all 0.15s ease;
    animation: fadeIn 0.3s ease;
    font-weight: 600;
}

#stats {
    background-color: var(--background-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    margin: 1rem 0;
    text-align: center;
}

#level {
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
    background-color: var(--primary-color);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    box-shadow: var(--shadow);
}

.controls {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-top: 20px;
}

button {
    padding: 0.8rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    border: none;
    border-radius: var(--border-radius);
    background-color: var(--primary-color);
    color: white;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 8px rgba(0, 0, 0, 0.15);
}

#pauseButton {
    position: absolute;
    top: 1rem;
    left: 1rem;
}

#languageSelector {
    position: absolute;
    top: 1rem;
    left: 50%;
    transform: translateX(-50%);
    padding: 0.5rem 1rem;
    font-size: 1rem;
    border: 2px solid var(--primary-color);
    border-radius: var(--border-radius);
    background-color: white;
    cursor: pointer;
    transition: var(--transition);
}

#optionsContainer {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin: 2rem 0;
}

.option-button {
    font-size: 1.5rem;
    padding: 1rem 2rem;
    border: 2px solid var(--primary-color);
    border-radius: var(--border-radius);
    background-color: white;
    cursor: pointer;
    transition: all 0.15s ease;
    min-width: 120px;
    box-shadow: var(--shadow);
    color: var(--text-color);
    font-weight: 500;
    text-transform: lowercase;
    letter-spacing: 0.5px;
    position: relative;
}

.option-button::before {
    content: attr(data-keyboard-hint);
    position: absolute;
    top: -8px;
    right: -8px;
    background-color: var(--primary-color);
    color: white;
    font-size: 0.8rem;
    font-weight: 600;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.option-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 8px rgba(0, 0, 0, 0.15);
    background-color: var(--primary-color);
    color: white;
}

.option-button.correct {
    background-color: var(--success-color);
    border-color: var(--success-color);
    color: white;
    transform: scale(1.01);
}

.option-button.incorrect {
    background-color: var(--error-color);
    border-color: var(--error-color);
    color: white;
}

#feedback {
    text-align: center;
    font-size: 1.5rem;
    font-weight: 600;
    margin: 1rem 0;
    min-height: 2em;
    transition: all 0.15s ease;
    padding: 1rem;
    background-color: var(--background-color);
    border-radius: var(--border-radius);
}

.correct-text {
    color: var(--success-color);
    background-color: rgba(46, 204, 113, 0.1);
}

.incorrect-text {
    color: var(--error-color);
    background-color: rgba(231, 76, 60, 0.1);
}

#score {
    text-align: center;
    font-size: 1.2rem;
    margin: 1rem 0;
    padding: 1rem;
    background-color: var(--background-color);
    border-radius: var(--border-radius);
}

/* Greeting styles */
#greeting {
    text-align: center;
    font-size: 1.5rem;
    margin: 1rem 0;
    cursor: default;
}

#username {
    font-weight: 600;
    cursor: pointer;
    border-bottom: 1px dashed var(--primary-color);
}

#username:focus {
    outline: none;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(5px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

.progress-bar {
    width: 100%;
    height: 8px;
    background-color: #e0e0e0;
    border-radius: 4px;
    margin: 1rem 0;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

@media (max-width: 600px) {
    .container {
        padding: 1rem;
    }

    #letter {
        font-size: 6rem;
    }

    .option-button {
        font-size: 1.2rem;
        padding: 0.8rem 1.5rem;
    }

    .controls {
        flex-direction: column;
    }
}

/* Reference Guide Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    overflow-y: auto;
    backdrop-filter: blur(4px);
}

.modal-content {
    background-color: #ffffff;
    margin: 3% auto;
    padding: 0;
    border-radius: 12px;
    width: 95%;
    max-width: 900px;
    position: relative;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

.modal-content h2 {
    background-color: #4a90e2;
    color: white;
    margin: 0;
    padding: 20px;
    text-align: center;
    font-size: 1.5rem;
    font-weight: 600;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.close-button {
    position: absolute;
    right: 15px;
    top: 15px;
    font-size: 24px;
    font-weight: 300;
    color: white;
    cursor: pointer;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.2);
    transition: all 0.2s ease;
}

.close-button:hover {
    background-color: rgba(255, 255, 255, 0.3);
    transform: scale(1.1);
}

/* Language Selector Styles */
.language-selector-container {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin: 0;
    padding: 20px;
    background-color: #f8f9fa;
    border-bottom: 1px solid #e9ecef;
}

.lang-tab {
    padding: 10px 24px;
    border: 2px solid #4a90e2;
    background-color: transparent;
    color: #4a90e2;
    border-radius: 25px;
    cursor: pointer;
    font-size: 15px;
    font-weight: 500;
    transition: all 0.3s ease;
    min-width: 100px;
    text-align: center;
}

.lang-tab:hover {
    background-color: rgba(74, 144, 226, 0.1);
    transform: translateY(-1px);
}

.lang-tab.active {
    background-color: #4a90e2;
    color: white;
    box-shadow: 0 2px 4px rgba(74, 144, 226, 0.2);
}

/* Reference Content Styles */
.reference-content {
    padding: 30px;
    max-height: 70vh;
    overflow-y: auto;
}

.reference-content::-webkit-scrollbar {
    width: 8px;
}

.reference-content::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

.reference-content::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

.reference-content::-webkit-scrollbar-thumb:hover {
    background: #a8a8a8;
}

.language-content {
    display: none;
    animation: fadeIn 0.3s ease;
}

.language-content.active {
    display: block;
}

.language-content h3 {
    color: #2c3e50;
    margin: 25px 0 15px;
    padding-bottom: 10px;
    border-bottom: 2px solid #e9ecef;
    font-size: 1.2rem;
    font-weight: 600;
}

.language-content h3:first-child {
    margin-top: 0;
}

/* Letter Grid Styles */
.letter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
    gap: 15px;
    margin-bottom: 30px;
}

.letter-item {
    background-color: #f8f9fa;
    padding: 15px 10px;
    border-radius: 8px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: all 0.2s ease;
    border: 1px solid #e9ecef;
}

.letter-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    border-color: #4a90e2;
    background-color: #ffffff;
}

.letter-item span {
    font-size: 28px;
    display: block;
    margin-bottom: 8px;
    color: #2c3e50;
    line-height: 1.2;
}

.letter-item::after {
    content: attr(data-pronunciation);
    display: block;
    font-size: 14px;
    color: #666;
    margin-top: 5px;
}

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

/* Responsive Styles */
@media (max-width: 768px) {
    .modal-content {
        margin: 0;
        width: 100%;
        height: 100%;
        border-radius: 0;
    }

    .modal-content h2 {
        padding: 15px;
        font-size: 1.3rem;
    }

    .language-selector-container {
        padding: 15px;
        gap: 8px;
    }

    .lang-tab {
        padding: 8px 16px;
        font-size: 14px;
        min-width: 80px;
    }

    .reference-content {
        padding: 20px;
        max-height: calc(100vh - 180px);
    }

    .letter-grid {
        grid-template-columns: repeat(auto-fill, minmax(90px, 1fr));
        gap: 10px;
    }

    .letter-item {
        padding: 12px 8px;
    }

    .letter-item span {
        font-size: 24px;
    }
}

@media (max-width: 480px) {
    .letter-grid {
        grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
        gap: 8px;
    }

    .letter-item {
        padding: 10px 6px;
    }

    .letter-item span {
        font-size: 22px;
    }

    .language-selector-container {
        flex-wrap: wrap;
    }

    .lang-tab {
        flex: 1;
        min-width: 0;
        padding: 8px 12px;
        font-size: 13px;
    }
}