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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: #F5F7FA;
    color: #333;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.app {
    max-width: 750px;
    margin: 0 auto;
    background-color: #fff;
    min-height: 100vh;
    position: relative;
}

.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 16px;
    background-color: #4A90D9;
    color: white;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-left,
.header-right {
    width: 40px;
    display: flex;
    align-items: center;
}

.header-title {
    flex: 1;
    text-align: center;
    font-size: 18px;
    font-weight: 500;
}

.back-btn,
.more-btn {
    background: none;
    border: none;
    color: white;
    cursor: pointer;
    padding: 8px;
}

.content {
    padding-bottom: 60px;
    min-height: calc(100vh - 120px);
}

.page {
    padding: 16px;
}

.video-container {
    position: relative;
    width: 100%;
    padding-top: 56.25%;
    background-color: #000;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 20px;
}

.video-placeholder {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background-color: #f0f0f0;
    color: #999;
}

.video-placeholder p {
    margin-top: 12px;
    font-size: 14px;
}

.video-player {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.play-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, 0.6);
    border: none;
    border-radius: 50%;
    width: 80px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s;
}

.play-btn:hover {
    background-color: rgba(0, 0, 0, 0.8);
    transform: translate(-50%, -50%) scale(1.1);
}

.sentence-section {
    background-color: #fff;
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.sentence-text {
    font-size: 18px;
    font-weight: 500;
    color: #333;
    line-height: 1.6;
    margin-bottom: 12px;
    text-align: center;
}

.audio-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    width: 100%;
    padding: 10px;
    background-color: #4A90D9;
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.audio-btn:hover {
    background-color: #3A80C9;
}

.audio-btn:active {
    background-color: #2A70B9;
}

.vocabulary-section {
    background-color: #fff;
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.section-title {
    font-size: 16px;
    font-weight: 500;
    color: #333;
    margin-bottom: 12px;
}

.vocabulary-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
}

.vocabulary-item {
    background-color: #F5F7FA;
    border-radius: 8px;
    padding: 12px;
    display: flex;
    flex-direction: column;
    gap: 4px;
    position: relative;
}

.vocab-word {
    font-size: 16px;
    font-weight: 500;
    color: #333;
}

.vocab-meaning {
    font-size: 14px;
    color: #666;
}

.vocab-audio-btn {
    position: absolute;
    top: 8px;
    right: 8px;
    background: none;
    border: none;
    color: #4A90D9;
    cursor: pointer;
    padding: 4px;
}

.interaction-section {
    display: flex;
    gap: 12px;
    margin-bottom: 20px;
}

.interaction-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px;
    background-color: #fff;
    border: 1px solid #E0E0E0;
    border-radius: 8px;
    font-size: 14px;
    color: #666;
    cursor: pointer;
    transition: all 0.3s;
}

.interaction-btn:hover {
    background-color: #F5F7FA;
}

.interaction-btn.active {
    color: #4CAF50;
    border-color: #4CAF50;
}

.interaction-btn .count {
    background-color: #F5F7FA;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 12px;
}

.practice-section {
    background-color: #fff;
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.practice-input {
    width: 100%;
    min-height: 80px;
    padding: 12px;
    border: 1px solid #E0E0E0;
    border-radius: 6px;
    font-size: 14px;
    resize: vertical;
    font-family: inherit;
}

.practice-input:focus {
    outline: none;
    border-color: #4A90D9;
}

.clear-btn {
    margin-top: 8px;
    padding: 8px 16px;
    background-color: #F5F7FA;
    color: #666;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    cursor: pointer;
}

.clear-btn:hover {
    background-color: #E0E0E0;
}

.navigation-section {
    display: flex;
    gap: 12px;
}

.nav-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px;
    background-color: #4A90D9;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.nav-btn:hover {
    background-color: #3A80C9;
}

.nav-btn:active {
    background-color: #2A70B9;
}

.create-form {
    padding: 16px;
}

.form-group {
    margin-bottom: 20px;
}

.form-label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    color: #333;
    margin-bottom: 8px;
}

.form-input,
.form-textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid #E0E0E0;
    border-radius: 6px;
    font-size: 14px;
    font-family: inherit;
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: #4A90D9;
}

.form-textarea {
    min-height: 80px;
    resize: vertical;
}

.upload-area {
    border: 2px dashed #E0E0E0;
    border-radius: 8px;
    padding: 32px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
}

.upload-area:hover {
    border-color: #4A90D9;
    background-color: #F5F7FA;
}

.upload-area p {
    margin-top: 12px;
    color: #666;
    font-size: 14px;
}

.upload-tip {
    font-size: 12px;
    color: #999;
    margin-top: 4px;
}

.video-preview,
.cover-preview {
    position: relative;
    margin-top: 12px;
}

.video-preview video,
.cover-preview img {
    width: 100%;
    border-radius: 8px;
}

.delete-btn {
    position: absolute;
    top: 8px;
    right: 8px;
    padding: 8px 16px;
    background-color: rgba(255, 0, 0, 0.8);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 12px;
    cursor: pointer;
}

.vocabulary-inputs {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.vocab-input-item {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.vocab-word-input,
.vocab-meaning-input {
    padding: 10px;
    border: 1px solid #E0E0E0;
    border-radius: 6px;
    font-size: 14px;
}

.add-vocab-btn {
    margin-top: 12px;
    padding: 10px 20px;
    background-color: #4A90D9;
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    cursor: pointer;
}

.add-vocab-btn:hover {
    background-color: #3A80C9;
}

.submit-btn {
    width: 100%;
    padding: 14px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    margin-top: 20px;
}

.submit-btn:hover {
    background-color: #3A9F40;
}

.user-info-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 32px 16px;
    background-color: #fff;
    margin-bottom: 12px;
}

.avatar-section {
    position: relative;
    margin-bottom: 16px;
}

.avatar-placeholder,
.avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: #F5F7FA;
    display: flex;
    align-items: center;
    justify-content: center;
}

.avatar {
    object-fit: cover;
}

.edit-avatar-btn {
    position: absolute;
    bottom: 0;
    right: 0;
    padding: 6px 12px;
    background-color: #4A90D9;
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 12px;
    cursor: pointer;
}

.user-name {
    font-size: 18px;
    font-weight: 500;
    color: #333;
    margin-bottom: 4px;
}

.user-id {
    font-size: 14px;
    color: #999;
}

.stats-section {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    padding: 16px;
    background-color: #fff;
    margin-bottom: 12px;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.stat-value {
    font-size: 24px;
    font-weight: 600;
    color: #4A90D9;
}

.stat-label {
    font-size: 12px;
    color: #666;
}

.menu-section {
    background-color: #fff;
    margin-bottom: 12px;
}

.menu-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px;
    border-bottom: 1px solid #F5F7FA;
    cursor: pointer;
    transition: background-color 0.3s;
}

.menu-item:last-child {
    border-bottom: none;
}

.menu-item:hover {
    background-color: #F5F7FA;
}

.menu-item span {
    flex: 1;
    font-size: 14px;
    color: #333;
}

.admin-section {
    background-color: #fff;
    padding: 16px;
}

.admin-title {
    font-size: 14px;
    font-weight: 500;
    color: #666;
    margin-bottom: 12px;
    padding-left: 4px;
}

.tab-bar {
    position: fixed;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    max-width: 750px;
    display: flex;
    background-color: #fff;
    border-top: 1px solid #E0E0E0;
    z-index: 100;
}

.tab-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    padding: 8px 0;
    color: #999;
    cursor: pointer;
    transition: color 0.3s;
}

.tab-item.active {
    color: #4CAF50;
}

.tab-item span {
    font-size: 12px;
}

@media (max-width: 480px) {
    .header {
        padding: 10px 12px;
    }

    .header-title {
        font-size: 16px;
    }

    .page {
        padding: 12px;
    }

    .vocabulary-list {
        grid-template-columns: 1fr;
    }

    .stats-section {
        grid-template-columns: repeat(2, 1fr);
    }

    .sentence-text {
        font-size: 16px;
    }
}

@media (min-width: 768px) {
    .app {
        box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
    }

    .header {
        padding: 16px 24px;
    }

    .page {
        padding: 24px;
    }

    .vocabulary-list {
        grid-template-columns: repeat(3, 1fr);
    }
}

.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px;
    color: #999;
}

.toast {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 16px 24px;
    border-radius: 8px;
    font-size: 14px;
    z-index: 1000;
    animation: fadeIn 0.3s;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal-content {
    background-color: #fff;
    border-radius: 8px;
    padding: 24px;
    max-width: 90%;
    width: 400px;
}

.modal-title {
    font-size: 18px;
    font-weight: 500;
    color: #333;
    margin-bottom: 16px;
}

.modal-message {
    font-size: 14px;
    color: #666;
    margin-bottom: 24px;
    line-height: 1.6;
}

.modal-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
}

.modal-btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    cursor: pointer;
}

.modal-btn.primary {
    background-color: #4A90D9;
    color: white;
}

.modal-btn.secondary {
    background-color: #F5F7FA;
    color: #666;
}

.modal-option {
    padding: 12px 16px;
    border-radius: 6px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.modal-option:hover {
    background-color: #F5F7FA;
}

.login-tips {
    background-color: #E3F2FD;
    padding: 12px;
    border-radius: 6px;
    margin-top: 16px;
}

.login-tips p {
    margin: 4px 0;
    font-size: 12px;
    color: #1976D2;
}

.login-tips p:first-child {
    font-weight: 500;
    margin-bottom: 8px;
}

.page-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px;
    background-color: #fff;
    border-bottom: 1px solid #F5F7FA;
}

.page-title {
    font-size: 18px;
    font-weight: 500;
    color: #333;
}

.list-container {
    padding: 16px;
    min-height: calc(100vh - 200px);
}

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    color: #999;
}

.empty-state svg {
    margin-bottom: 16px;
}

.empty-state p {
    font-size: 14px;
}

.corpus-item {
    background-color: #fff;
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.corpus-item-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    margin-bottom: 12px;
}

.corpus-item-title {
    font-size: 16px;
    font-weight: 500;
    color: #333;
    flex: 1;
}

.corpus-item-status {
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 12px;
    margin-left: 8px;
}

.corpus-item-status.pending {
    background-color: #FFF3E0;
    color: #FF9800;
}

.corpus-item-status.approved {
    background-color: #E8F5E9;
    color: #4CAF50;
}

.corpus-item-status.rejected {
    background-color: #FFEBEE;
    color: #F44336;
}

.corpus-item-sentence {
    font-size: 14px;
    color: #666;
    line-height: 1.6;
    margin-bottom: 12px;
}

.corpus-item-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 12px;
    color: #999;
}

.corpus-item-actions {
    display: flex;
    gap: 8px;
}

.corpus-item-action-btn {
    padding: 6px 12px;
    background-color: #F5F7FA;
    color: #666;
    border: none;
    border-radius: 4px;
    font-size: 12px;
    cursor: pointer;
    transition: all 0.3s;
}

.corpus-item-action-btn:hover {
    background-color: #E0E0E0;
}

.corpus-item-action-btn.approve {
    background-color: #E8F5E9;
    color: #4CAF50;
}

.corpus-item-action-btn.reject {
    background-color: #FFEBEE;
    color: #F44336;
}

.about-content {
    padding: 16px;
}

.about-section {
    background-color: #fff;
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.about-title {
    font-size: 18px;
    font-weight: 500;
    color: #333;
    margin-bottom: 12px;
    text-align: center;
}

.about-text {
    font-size: 14px;
    color: #666;
    line-height: 1.8;
    margin-bottom: 16px;
}

.about-images {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
}

.about-image {
    max-width: 200px;
    border-radius: 8px;
}

.about-contact {
    font-size: 14px;
    color: #666;
    text-align: center;
}

.about-edit-form {
    padding: 16px;
}