* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Arial', 'Microsoft YaHei', sans-serif;
}
body {
    background-color: #f5f7fa;
    padding: 20px;
    display: flex;
    justify-content: center;
    min-height: 100vh;
}
.main-container {
    display: flex;
    gap: 25px;
    max-width: 1200px;
    width: 100%;
}
.left-section {
    flex: 9;
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 15px rgba(0,0,0,0.08);
    padding: 30px;
    overflow-y: auto;
    max-height: calc(100vh - 40px);
}
.right-section {
    flex: 4;
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 15px rgba(0,0,0,0.08);
    padding: 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: sticky;
    top: 20px;
    height: calc(100vh - 40px);
}
h1 {
    text-align: center;
    color: #2d3748;
    margin-bottom: 30px;
    font-size: 28px;
}
.control-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    flex-wrap: wrap;
    gap: 10px;
}
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    background: #4299e1;
    color: white;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s;
}
.btn:hover {
    background: #3182ce;
    transform: translateY(-2px);
}
.btn:active {
    transform: translateY(0);
}
.btn.reset {
    background: #ed8936;
}
.btn.reset:hover {
    background: #dd6b20;
}
.word-count {
    color: #718096;
    font-size: 15px;
}
.word-list {
    display: grid;
    gap: 18px;
}
.word-card {
    background: #f8f9fa;
    border-radius: 8px;
    padding: 20px;
    border-left: 4px solid #4299e1;
    transition: all 0.3s;
}
.word-card:hover {
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
    transform: translateX(5px);
}
.word-card.active {
    border-left-color: #48bb78;
    background: #f0fdf4;
    box-shadow: 0 4px 15px rgba(72, 187, 120, 0.15);
}
.word-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}
.word {
    font-size: 22px;
    font-weight: bold;
    color: #2d3748;
}
.translations-container {
    margin-bottom: 15px;
}
.translation-item {
    font-size: 17px;
    color: #4a5568;
    padding: 5px 0;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
}
.translation-item.hidden {
    background: #e2e8f0;
    color: transparent;
    user-select: none;
    border-radius: 4px;
}
.translation-item.hidden:hover {
    background: #cbd5e0;
}
.pos-tag {
    padding: 2px 8px;
    background: #e8f4f8;
    color: #4299e1;
    border-radius: 12px;
    font-size: 13px;
    white-space: nowrap;
}
.phrases-title {
    font-size: 15px;
    color: #718096;
    margin-bottom: 8px;
}
.phrase-list {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}
.phrase-item {
    background: #f0f8fb;
    padding: 6px 12px;
    border-radius: 4px;
    font-size: 14px;
}
.phrase-eng {
    color: #2d3748;
    font-weight: 500;
}
.phrase-cn {
    color: #718096;
    margin-left: 6px;
}
.input-container {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 20px;
    text-align: center;
}
.input-title {
    font-size: 22px;
    color: #2d3748;
    font-weight: 600;
}
.word-input {
    width: 100%;
    padding: 15px;
    font-size: 18px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    outline: none;
    transition: border-color 0.3s;
}
.word-input:focus {
    border-color: #4299e1;
    box-shadow: 0 0 0 3px rgba(66, 153, 225, 0.1);
}
.feedback {
    font-size: 18px;
    font-weight: 500;
    min-height: 24px;
}
.feedback.correct {
    color: #48bb78;
}
.feedback.error {
    color: #e53e3e;
}
.progress {
    color: #718096;
    font-size: 16px;
}
@media (max-width: 900px) {
    .main-container {
        flex-direction: column;
    }
    .right-section {
        height: auto;
        position: static;
        margin-top: 20px;
    }
    .left-section, .right-section {
        max-height: none;
    }
}
@media (max-width: 600px) {
    .left-section, .right-section {
        padding: 20px 15px;
    }
    .word {
        font-size: 20px;
    }
    .control-bar {
        flex-direction: column;
        align-items: flex-start;
    }
}