:root {
    --primary: #7CB342;
    --primary-light: #9CCC65;
    --secondary: #558B2F;
    --accent: #F9A825;
    --danger: #E17055;
    --bg: #F9FBE7;
    --card-bg: #FFFFFF;
    --text: #33691E;
    --text-light: #689F38;
    --shadow: 0 4px 15px rgba(124, 179, 66, 0.12);
    --shadow-hover: 0 8px 25px rgba(124, 179, 66, 0.22);
    --radius: 16px;
}

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

body {
    font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
}

.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
    transition: all 0.3s;
    border: none;
}
.card:hover { box-shadow: var(--shadow-hover); }

.stat-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.stat-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 20px;
    text-align: center;
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}
.stat-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 4px;
}
.stat-card.purple::before { background: var(--primary); }
.stat-card.green::before { background: var(--secondary); }
.stat-card.yellow::before { background: var(--accent); }
.stat-card.red::before { background: var(--danger); }

.stat-number { font-size: 36px; font-weight: 800; margin: 8px 0 4px; }
.stat-card.purple .stat-number { color: var(--primary); }
.stat-card.green .stat-number { color: var(--secondary); }
.stat-card.yellow .stat-number { color: #F39C12; }
.stat-card.red .stat-number { color: var(--danger); }
.stat-label { font-size: 14px; color: var(--text-light); font-weight: 500; }

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 12px;
}
.category-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 16px;
    text-align: center;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    color: var(--text);
    display: block;
}
.category-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); }
.category-icon { font-size: 36px; margin-bottom: 8px; }
.category-name { font-size: 15px; font-weight: 600; margin-bottom: 4px; }
.category-count { font-size: 12px; color: var(--text-light); }

.btn-primary {
    background: linear-gradient(135deg, var(--primary), #8BC34A);
    color: white; border: none;
    box-shadow: 0 4px 12px rgba(124, 179, 66, 0.3);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 18px rgba(124, 179, 66, 0.4);
    background: linear-gradient(135deg, var(--primary), #8BC34A);
    color: white;
}
.btn-success {
    background: linear-gradient(135deg, var(--secondary), #00D2A0);
    color: white; border: none;
    box-shadow: 0 4px 12px rgba(0, 184, 148, 0.3);
}
.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 18px rgba(0, 184, 148, 0.4);
    background: linear-gradient(135deg, var(--secondary), #00D2A0);
    color: white;
}
.btn-warning {
    background: linear-gradient(135deg, var(--accent), #F9CA24);
    color: #5D4E37; border: none;
    box-shadow: 0 4px 12px rgba(253, 203, 110, 0.4);
}
.btn-warning:hover {
    transform: translateY(-2px);
    background: linear-gradient(135deg, var(--accent), #F9CA24);
    color: #5D4E37;
}
.btn-danger {
    background: linear-gradient(135deg, var(--danger), #FF7675);
    color: white; border: none;
    box-shadow: 0 4px 12px rgba(225, 112, 85, 0.3);
}
.btn-danger:hover {
    transform: translateY(-2px);
    background: linear-gradient(135deg, var(--danger), #FF7675);
    color: white;
}
.btn-outline {
    background: transparent;
    border: 2px solid var(--primary);
    color: var(--primary);
}
.btn-outline:hover {
    background: var(--primary);
    color: white;
}

.section-title {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Character grid */
.character-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 12px;
}
.character-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 12px;
    text-align: center;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    color: var(--text);
    display: block;
    position: relative;
}
.character-card:hover { transform: translateY(-4px) scale(1.03); box-shadow: var(--shadow-hover); }
.character-card .char { font-size: 64px; width: 80px; height: 80px; margin: 0 auto 4px; }
.character-card .pinyin { font-size: 16px; color: var(--primary); font-weight: 600; }
.character-card .meaning {
    font-size: 14px; color: var(--text-light); margin-top: 2px;
    overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.mastery-dot { position: absolute; top: 8px; right: 8px; width: 10px; height: 10px; border-radius: 50%; }
.mastery-dot.new { background: #DFE6E9; }
.mastery-dot.learning { background: var(--accent); }
.mastery-dot.good { background: #74B9FF; }
.mastery-dot.mastered { background: var(--secondary); }
.char-meta { display: flex; justify-content: space-between; margin-top: 6px; font-size: 12px; color: var(--text-light); }
.character-card .example-word { font-size: 14px; color: var(--text-light); margin-top: 3px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.char-grade { background: #E8F5E9; color: var(--primary); padding: 1px 6px; border-radius: 6px; font-size: 12px; }
.char-strokes { font-size: 12px; color: var(--text-light); }
.char-strokes.stroke-btn { cursor: pointer; background: var(--primary); color: white; padding: 1px 6px; border-radius: 6px; font-size: 12px; }
.char-strokes.stroke-btn:hover { opacity: 0.85; }
.sub-title-recognition { background: #FFF3E0; border-left: 4px solid #E74C3C; padding: 8px 12px; border-radius: 8px; margin: 16px 0 10px; font-size: 16px; font-weight: 700; }
.sub-title-writing { background: #E3F2FD; border-left: 4px solid #1A6BD5; padding: 8px 12px; border-radius: 8px; margin: 16px 0 10px; font-size: 16px; font-weight: 700; }

/* Flashcard */
.flashcard-container { display: flex; flex-direction: column; align-items: center; padding: 20px; }
.flashcard { width: 100%; max-width: 480px; min-height: 420px; perspective: 1000px; cursor: pointer; margin-bottom: 24px; }
.flashcard-inner { position: relative; width: 100%; height: 420px; transition: transform 0.6s; transform-style: preserve-3d; }
.flashcard.flipped .flashcard-inner { transform: rotateY(180deg); }
.flashcard-front, .flashcard-back {
    position: absolute; width: 100%; height: 100%;
    backface-visibility: hidden; border-radius: var(--radius);
    display: flex; flex-direction: column; align-items: center; justify-content: center;
    box-shadow: var(--shadow);
}
.flashcard-front { background: linear-gradient(135deg, #FFFFFF, #F9FBE7); }
.flashcard-back { background: linear-gradient(135deg, var(--primary), #8BC34A); color: white; transform: rotateY(180deg); }
.flashcard-char { font-size: 96px; line-height: 1; margin-bottom: 16px; }
.flashcard-back .flashcard-char { font-size: 56px; margin-bottom: 8px; }
.flashcard-hint { font-size: 14px; color: var(--text-light); }
.flashcard-back .pinyin-text { font-size: 32px; font-weight: 700; margin-bottom: 12px; }
.flashcard-back .meaning-text { font-size: 20px; margin-bottom: 8px; }
.flashcard-back .example-word { font-size: 16px; margin-top: 10px; padding: 6px 14px; background: rgba(255,255,255,0.15); border-radius: 8px; }
.flashcard-back .example-sentence { font-size: 14px; margin-top: 8px; padding: 6px 14px; background: rgba(255,255,255,0.1); border-radius: 8px; opacity: 0.9; }
.flashcard-actions { display: flex; gap: 16px; margin-top: 16px; }

.progress-bar-container { width: 100%; max-width: 480px; margin-bottom: 24px; }
.progress-bar { height: 8px; background: #DFE6E9; border-radius: 4px; overflow: hidden; }
.progress-bar-fill { height: 100%; background: linear-gradient(90deg, var(--primary), var(--secondary)); border-radius: 4px; transition: width 0.3s; }
.progress-text { text-align: center; font-size: 14px; color: var(--text-light); margin-top: 8px; }

/* Quiz */
.quiz-container { max-width: 600px; margin: 0 auto; }
.quiz-question { text-align: center; margin-bottom: 24px; }
.quiz-char { font-size: 80px; margin-bottom: 8px; }
.quiz-prompt { font-size: 16px; color: var(--text-light); }
.quiz-options { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-bottom: 24px; }
.quiz-option {
    padding: 16px; border-radius: var(--radius); border: 2px solid #DFE6E9;
    background: white; font-size: 18px; cursor: pointer; transition: all 0.2s; text-align: center;
}
.quiz-option:hover { border-color: var(--primary); background: #F1F8E9; }
.quiz-option.correct { border-color: var(--secondary); background: #E8FFF7; color: var(--secondary); }
.quiz-option.wrong { border-color: var(--danger); background: #FFF0EC; color: var(--danger); }
.quiz-option.disabled { pointer-events: none; opacity: 0.7; }

/* Result */
.result-container { max-width: 600px; margin: 0 auto; text-align: center; }
.result-score { font-size: 64px; font-weight: 800; margin: 16px 0; }
.result-score.great { color: var(--secondary); }
.result-score.good { color: var(--primary); }
.result-score.ok { color: var(--accent); }
.result-score.poor { color: var(--danger); }
.result-item {
    display: flex; align-items: center; padding: 12px 16px; border-radius: 12px;
    margin-bottom: 8px; background: var(--card-bg); box-shadow: var(--shadow);
}
.result-item .char { font-size: 32px; width: 50px; text-align: center; }
.result-item .info { flex: 1; text-align: left; margin-left: 12px; }
.result-item .info .pinyin { font-size: 15px; font-weight: 600; color: var(--primary); }
.result-item .info .meaning { font-size: 13px; color: var(--text-light); }
.result-item .status { font-size: 24px; }

/* Progress page */
.progress-category {
    display: flex; align-items: center; padding: 16px; background: var(--card-bg);
    border-radius: var(--radius); margin-bottom: 8px; box-shadow: var(--shadow);
}
.progress-category .name { width: 80px; font-weight: 600; }
.progress-category .bar-wrap { flex: 1; margin: 0 16px; }
.progress-category .bar { height: 12px; background: #DFE6E9; border-radius: 6px; overflow: hidden; }
.progress-category .bar-fill { height: 100%; background: linear-gradient(90deg, var(--primary), var(--secondary)); border-radius: 6px; transition: width 0.5s; }
.progress-category .percent { width: 50px; text-align: right; font-weight: 700; color: var(--primary); }

/* Filter bar */
.filter-bar { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 16px; align-items: center; }

/* Grade cards */
.grade-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 16px; margin-bottom: 24px; }
.grade-card {
    background: var(--card-bg); border-radius: var(--radius); padding: 20px;
    text-align: center; box-shadow: var(--shadow); transition: all 0.3s;
    border-top: 4px solid var(--grade-color);
}
.grade-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); }
.grade-header { display: flex; align-items: baseline; justify-content: center; gap: 4px; margin-bottom: 12px; }
.grade-num { font-size: 36px; font-weight: 800; color: var(--grade-color); }
.grade-label { font-size: 16px; font-weight: 600; color: var(--text-light); }
.grade-info { display: flex; flex-direction: column; gap: 4px; margin-bottom: 12px; }
.grade-total { font-size: 14px; font-weight: 600; color: var(--text); }
.grade-mastered { font-size: 12px; color: var(--secondary); font-weight: 500; }
.grade-bar { height: 6px; background: #DFE6E9; border-radius: 3px; overflow: hidden; margin-bottom: 12px; }
.grade-bar-fill { height: 100%; background: linear-gradient(90deg, var(--grade-color), var(--primary)); border-radius: 3px; transition: width 0.5s; }
.grade-actions { display: flex; gap: 8px; justify-content: center; }
.grade-link {
    padding: 4px 14px; border-radius: 14px; font-size: 13px; font-weight: 600;
    text-decoration: none; color: var(--grade-color); background: rgba(124, 179, 66, 0.06); transition: all 0.2s;
}
.grade-link:hover { background: var(--grade-color); color: white; }

/* Grade quick grid */
.grade-quick-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 12px; }
.grade-quick-card {
    background: var(--card-bg); border-radius: var(--radius); padding: 16px;
    text-align: center; box-shadow: var(--shadow); transition: all 0.3s;
    border-left: 4px solid var(--grade-color);
}
.grade-quick-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); }
.gq-num { font-size: 20px; font-weight: 700; color: var(--grade-color); margin-bottom: 8px; }
.gq-links { display: flex; gap: 8px; justify-content: center; }
.gq-links a {
    padding: 4px 12px; border-radius: 14px; font-size: 13px; font-weight: 600;
    text-decoration: none; color: var(--grade-color); background: rgba(124, 179, 66, 0.06); transition: all 0.2s;
}
.gq-links a:hover { background: var(--grade-color); color: white; }

/* Mode cards */
.mode-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; margin: 24px 0; }
.mode-card {
    background: var(--card-bg); border-radius: var(--radius); padding: 24px;
    text-align: center; box-shadow: var(--shadow); transition: all 0.3s;
    cursor: pointer; text-decoration: none; color: var(--text);
}
.mode-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); }
.mode-card .icon { font-size: 48px; margin-bottom: 12px; }
.mode-card .title { font-size: 18px; font-weight: 700; margin-bottom: 8px; }
.mode-card .desc { font-size: 14px; color: var(--text-light); }

/* Lesson list */
.lesson-list { display: flex; flex-direction: column; gap: 8px; }
.lesson-card {
    display: flex; align-items: center; justify-content: space-between;
    padding: 14px 20px; background: var(--card-bg); border-radius: var(--radius);
    box-shadow: var(--shadow); transition: all 0.3s;
}
.lesson-card:hover { box-shadow: var(--shadow-hover); }
.lesson-info { display: flex; align-items: center; gap: 12px; }
.lesson-unit { font-size: 12px; color: var(--text-light); background: #E8F5E9; padding: 2px 8px; border-radius: 8px; }
.lesson-title { font-size: 16px; font-weight: 600; }
.lesson-count { font-size: 13px; color: var(--text-light); }
.lesson-actions { display: flex; gap: 6px; }

/* Footer */
.site-footer { text-align: center; padding: 20px; color: var(--text-light); font-size: 13px; margin-top: 32px; border-top: 1px solid #E8E8E8; }

/* Animations */
@keyframes fadeIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }
.fade-in { animation: fadeIn 0.4s ease-out; }

/* Responsive */
@media (max-width: 600px) {
    .stat-grid { grid-template-columns: repeat(2, 1fr); }
    .category-grid { grid-template-columns: repeat(2, 1fr); }
    .character-grid { grid-template-columns: repeat(3, 1fr); }
    .quiz-options { grid-template-columns: 1fr; }
}