@import url('https://fonts.googleapis.com/css2?family=Quicksand:wght@500&display=swap');

:root {
    --font-color: #2c3e50;
    --card-shadow: rgba(0, 0, 0, 0.1);
    --accent-color: #ff7e5f;
    --active-color: #58a6ff;
    --success-color: #4CAF50;
    --error-color: #F44336;
    --glass-bg: rgba(255, 255, 255, 0.7);
    --bg-gradient: linear-gradient(135deg, #e0f2f1 0%, #b2dfdb 100%);
    --front-face-gradient: linear-gradient(135deg, #fbc2eb 0%, #a6c1ee 100%);
    --theme-seion: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    --theme-dakuon: linear-gradient(135deg, #5ee7df 0%, #b490ca 100%);
    --theme-handakuon: linear-gradient(135deg, #d299c2 0%, #fef9d7 100%);
    --theme-yoon: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --text-color-seion: #2b8a8c;
    --text-color-dakuon: #473b6b;
    --text-color-handakuon: #b16393;
    --text-color-yoon: #c74355;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    margin: 0;
    background: var(--bg-gradient);
    color: var(--font-color);
    line-height: 1.6;
}

header {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    padding: 0.75rem 2rem;
    box-shadow: 0 2px 10px var(--card-shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    justify-content: center;
    align-items: center;
}

main {
    padding: 2rem;
}

.card-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 1.5rem;
}

.card {
    position: relative;
    perspective: 1000px;
    background: none;
}

.card-flipper {
    width: 100%;
    transform-style: preserve-3d;
    transition: transform 0.5s;
    aspect-ratio: 4 / 5;
}

.card.flipped .card-flipper { transform: rotateY(180deg); }

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    border-radius: 12px;
    padding: 10px;
    box-sizing: border-box;
    box-shadow: 0 4px 15px var(--card-shadow);
}

.card-front { background: var(--front-face-gradient); }
.card-back { transform: rotateY(180deg); }

.card-type-seion .card-back { background-image: var(--theme-seion); color: var(--text-color-seion); }
.card-type-dakuon .card-back { background-image: var(--theme-dakuon); color: var(--text-color-dakuon); }
.card-type-handakuon .card-back { background-image: var(--theme-handakuon); color: var(--text-color-handakuon); }
.card-type-yoon .card-back { background-image: var(--theme-yoon); color: var(--text-color-yoon); }

.romaji { font-family: 'Quicksand', sans-serif; font-size: 1.8rem; font-weight: 500; color: black; }
.kana { font-size: 2.5rem; text-align: center; line-height: 1.2; }

.speaker-icon { width: 24px; height: 24px; position: absolute; bottom: 10px; right: 10px; opacity: 0.6; transition: opacity 0.2s; z-index: 5; cursor: pointer; filter: drop-shadow(0 1px 1px rgba(0,0,0,0.2)); }

#controls {
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2rem;
}

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

.control-group input[type="checkbox"] { display: none; }

.control-group label, #shuffle-btn {
    padding: 0.5rem 1rem;
    border: 1px solid #ddd;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
    background-color: #f8f8f8;
}

.control-group input[type="checkbox"]:checked + label { background-color: var(--active-color); color: #fff; border-color: var(--active-color); }

#shuffle-btn { font-size: 1.2rem; line-height: 1; }
#shuffle-btn.active { background-color: var(--accent-color); color: #fff; border-color: var(--accent-color); }

#start-test-btn {
    padding: 0.7rem 1.5rem;
    border-radius: 8px;
    border: none;
    background: linear-gradient(45deg, #6a11cb, #2575fc);
    color: #fff;
    font-weight: bold;
    font-size: 1.1rem;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

#start-test-btn:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(0,0,0,0.2); }

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}

.modal-content {
    background-color: #fff;
    padding: 2rem;
    border-radius: 10px;
    width: 90%;
    max-width: 480px;
    text-align: center;
    position: relative;
}

.close-modal-btn {
    position: absolute;
    top: 10px;
    right: 15px;
    background: none;
    border: none;
    font-size: 2rem;
    color: #aaa;
    cursor: pointer;
    line-height: 1;
    padding: 0;
}

.close-modal-btn:hover { color: #333; }

#test-card {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 1rem auto;
}

#test-card .card {
    width: 120px;
    height: 150px;
}

#test-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
    margin: 1rem 0;
}

#test-options button {
    padding: 0.75rem;
    font-size: 1rem;
    border: 1px solid #ccc;
    border-radius: 8px;
    background-color: #f9f9f9;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.2s;
}

#test-options button:hover { transform: translateY(-2px); }

#test-options button.correct {
    background-color: var(--success-color);
    color: white;
}

#test-options button.incorrect {
    background-color: var(--error-color);
    color: white;
}

#feedback { display: none; }

#next-btn-container { margin-top: 1rem; text-align: center; }

#next-btn {
    padding: 0.6rem 2.5rem;
    border-radius: 20px;
    border: none;
    background-color: var(--accent-color);
    color: white;
    font-weight: bold;
    cursor: pointer;
    transition: transform 0.2s;
}

#next-btn:hover { transform: scale(1.05); }