:root {
    --primary-color: #4a90e2;
    --secondary-color: #f5a623;
    --background-color: #f7f9fb;
    --card-background: #ffffff;
    --text-color: #333;
    --light-text-color: #888;
    --border-color: #e0e0e0;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --font-family: 'Noto Sans', 'Noto Sans KR', sans-serif;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-image: subtle-noise-texture.png;
}

header {
    width: 100%;
    max-width: 800px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

h1 {
    font-size: 2rem;
    color: var(--primary-color);
    text-shadow: 1px 1px 2px var(--shadow-color);
}

.settings-container select {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    background-color: var(--card-background);
}

#tab-nav {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.tab-link {
    padding: 10px 20px;
    font-size: 1rem;
    font-weight: 700;
    border: none;
    background-color: transparent;
    color: var(--light-text-color);
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s, color 0.3s;
}

.tab-link.active {
    background-color: var(--primary-color);
    color: white;
    box-shadow: 0 2px 8px rgba(74, 144, 226, 0.4);
}

main {
    width: 100%;
    max-width: 800px;
}

.tab-content {
    display: none;
}

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

/* Flashcard Styles */
#flashcard-container {
    perspective: 1000px;
    height: 350px;
}

.flashcard {
    width: 100%;
    height: 100%;
    position: relative;
    cursor: pointer;
}

.flashcard-inner {
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    position: absolute;
}

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

.flashcard-front,
.flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background-color: var(--card-background);
    border-radius: 15px;
    box-shadow: 0 4px 15px var(--shadow-color);
    padding: 20px;
    box-sizing: border-box;
}

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

.word-info {
    text-align: center;
    margin-bottom: 20px;
}

.korean-word {
    font-size: 3.5rem;
    margin: 0;
}

.romanization {
    font-size: 1.5rem;
    color: var(--light-text-color);
    margin-top: 5px;
}

.example-sentence-korean, .example-sentence-translation {
    font-size: 1.2rem;
    text-align: center;
    margin-top: 20px;
}

.meaning {
    font-size: 2rem;
    color: var(--primary-color);
}

.card-actions {
    position: absolute;
    top: 20px;
    right: 20px;
    display: flex;
    gap: 10px;
}

.pronounce-btn, .favorite-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--light-text-color);
}

.favorite-btn.favorited {
    color: var(--secondary-color);
}

.flashcard-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
}

.flashcard-nav button {
    padding: 12px 25px;
    font-size: 1rem;
    border: none;
    border-radius: 8px;
    background-color: var(--primary-color);
    color: white;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(74, 144, 226, 0.3);
    transition: background-color 0.3s;
}

.flashcard-nav button:hover {
    background-color: #3a80d2;
}

/* Quiz Styles */
#quiz-container {
    background-color: var(--card-background);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 4px 15px var(--shadow-color);
}

#quiz-container .question {
    font-size: 1.8rem;
    margin-bottom: 20px;
}

#quiz-container .options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

#quiz-container .option {
    padding: 15px;
    font-size: 1.1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s, border-color 0.3s;
}

#quiz-container .option:hover {
    background-color: #e9f2fe;
}

#quiz-container .option.correct {
    background-color: #d4edda;
    border-color: #c3e6cb;
}

#quiz-container .option.incorrect {
    background-color: #f8d7da;
    border-color: #f5c6cb;
}

#start-quiz, #review-wrong-answers {
    display: block;
    margin: 20px auto;
    padding: 15px 30px;
    font-size: 1.2rem;
    border: none;
    border-radius: 8px;
    background-color: var(--secondary-color);
    color: white;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(245, 166, 35, 0.4);
}

/* Vocabulary List Styles */
.filters {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

#search-bar, #category-filter {
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
}

#search-bar {
    flex-grow: 1;
}

#favorites-filter {
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--card-background);
    cursor: pointer;
}

#vocabulary-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 15px;
}

.vocab-item {
    background-color: var(--card-background);
    padding: 15px;
    border-radius: 10px;
    box-shadow: 0 2px 8px var(--shadow-color);
    display: flex;
    flex-direction: column;
}

.vocab-item .korean-word {
    font-size: 1.5rem;
    font-weight: 700;
}

.vocab-item .romanization {
    font-size: 1rem;
    color: var(--light-text-color);
}

.vocab-item .meaning {
    font-size: 1.1rem;
    margin-top: 10px;
    color: var(--primary-color);
}

/* Responsive Design */
@media (max-width: 600px) {
    body {
        padding: 10px;
    }

    h1 {
        font-size: 1.5rem;
    }

    #tab-nav {
        gap: 5px;
        justify-content: center;
				flex-wrap: wrap;
    }

    .tab-link {
        padding: 8px 12px;
        font-size: 0.9rem;
    }

    #flashcard-container {
        height: 300px;
    }

    .korean-word {
        font-size: 2.5rem;
    }

    .romanization {
        font-size: 1.2rem;
    }

    .filters {
        flex-direction: column;
    }
}