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

:root {
  --primary-color: #1677ff;
  --primary-hover: #4096ff;
  --success-color: #07c160;
  --warning-color: #ff9900;
  --danger-color: #ff4d4f;
  --text-primary: #1a1a1a;
  --text-secondary: #666;
  --text-placeholder: #999;
  --border-color: #e5e5e5;
  --bg-color: #f5f5f5;
  --card-bg: #fff;
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

/* 页面容器 */
.page {
  min-height: 100vh;
  background-color: var(--bg-color);
}

.page.hidden {
  display: none;
}

/* 容器 */
.container {
  max-width: 600px;
  margin: 0 auto;
  padding: 0 16px;
}

/* 登录页 */
.login-container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 40px 20px;
}

.login-header {
  text-align: center;
  margin-bottom: 40px;
}

.login-header h1 {
  font-size: 28px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.login-header p {
  font-size: 14px;
  color: var(--text-secondary);
}

.login-form {
  width: 100%;
  max-width: 360px;
}

/* 表单项 */
.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 12px 16px;
  font-size: 16px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background-color: #fff;
  transition: border-color 0.2s;
  font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--primary-color);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 20px;
  font-size: 16px;
  font-weight: 500;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
  text-decoration: none;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background-color: var(--primary-color);
  color: #fff;
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--primary-hover);
}

.btn-secondary {
  background-color: #fff;
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--bg-color);
}

.btn-outline {
  background-color: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.btn-outline:hover:not(:disabled) {
  background-color: var(--bg-color);
}

.btn-text {
  background: none;
  color: var(--primary-color);
  padding: 8px 12px;
}

.btn-text:hover {
  background-color: rgba(22, 119, 255, 0.1);
}

.btn-large {
  height: 48px;
  width: 100%;
  font-size: 17px;
}

.btn-small {
  height: 32px;
  padding: 0 12px;
  font-size: 14px;
}

.btn-success {
  background-color: var(--success-color);
  color: #fff;
}

.btn-success:hover:not(:disabled) {
  background-color: #06ad56;
}

.btn-danger {
  background-color: var(--danger-color);
  color: #fff;
}

.btn-danger:hover:not(:disabled) {
  background-color: #ff7875;
}

/* 头部 */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px;
  background-color: #fff;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header h2 {
  font-size: 17px;
  font-weight: 600;
}

.header-left {
  flex: 1;
}

.welcome {
  font-size: 16px;
  color: var(--text-primary);
}

/* 统计卡片 */
.stats-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  padding: 20px 16px;
  max-width: 600px;
  margin: 0 auto;
}

.stat-card {
  background-color: #fff;
  border-radius: 12px;
  padding: 20px 16px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-number {
  font-size: 32px;
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 8px;
}

.stat-label {
  font-size: 13px;
  color: var(--text-secondary);
}

/* 操作按钮 */
.action-buttons {
  padding: 0 16px 20px;
  max-width: 600px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* 表单容器 */
.form-container {
  max-width: 600px;
  margin: 0 auto;
  padding: 20px 16px;
  background-color: #fff;
}

/* 列表 */
.list-container {
  max-width: 600px;
  margin: 0 auto;
  padding: 16px;
}

.list-item {
  background-color: #fff;
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
  box-shadow: var(--shadow);
}

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

.list-item-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
}

.list-item-meta {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

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

/* 空状态 */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-secondary);
}

.empty-state-icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.empty-state-text {
  font-size: 15px;
}

/* 加载状态 */
.loading {
  text-align: center;
  padding: 40px 20px;
  color: var(--text-secondary);
}

/* 标签 */
.tag {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 500;
}

.tag-submitted {
  background-color: #fff7e6;
  color: var(--warning-color);
}

.tag-published {
  background-color: #f6ffed;
  color: var(--success-color);
}

.tag-rejected {
  background-color: #fff2f0;
  color: var(--danger-color);
}

.tag-active {
  background-color: #e6f7ff;
  color: var(--primary-color);
}

/* 提交项样式 */
.submission-item {
  background-color: #fff;
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
  box-shadow: var(--shadow);
}

.submission-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.submission-student {
  font-size: 16px;
  font-weight: 600;
}

.submission-score {
  font-size: 14px;
  color: var(--text-secondary);
}

.submission-score span {
  font-size: 20px;
  font-weight: 600;
  color: var(--primary-color);
}

.submission-feedback {
  background-color: var(--bg-color);
  border-radius: 8px;
  padding: 12px;
  margin-bottom: 12px;
}

.submission-feedback-label {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.submission-feedback-content {
  font-size: 14px;
  color: var(--text-primary);
  white-space: pre-wrap;
  line-height: 1.6;
}

.submission-edit-textarea {
  width: 100%;
  padding: 12px;
  font-size: 14px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background-color: #fff;
  resize: vertical;
  min-height: 120px;
  font-family: inherit;
  line-height: 1.6;
  transition: border-color 0.2s;
}

.submission-edit-textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  background-color: #fff;
}

.submission-actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

.submission-actions .btn {
  flex: 1;
}

/* Toast 提示 */
.toast {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: rgba(0, 0, 0, 0.75);
  color: #fff;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 14px;
  z-index: 9999;
  pointer-events: none;
  animation: toast-fade 0.3s ease;
}

.toast.hidden {
  display: none;
}

@keyframes toast-fade {
  from {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.9);
  }
  to {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
  }
}

/* 学情统计卡片（功能6） */
.stats-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 16px;
}

.stat-card-small {
  background-color: #fff;
  border-radius: 12px;
  padding: 16px 12px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-number-small {
  font-size: 24px;
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 4px;
}

.stat-label-small {
  font-size: 12px;
  color: var(--text-secondary);
}

/* 音频播放器 */
.submission-audio {
  margin: 12px 0;
}

.submission-audio audio {
  width: 100%;
  border-radius: 8px;
}

/* 标签样式 */
.tag-closed {
  background-color: #f5f5f5;
  color: #999;
}

/* 表单下拉框 */
.form-select {
  width: 100%;
  padding: 12px 16px;
  font-size: 16px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background-color: #fff;
  transition: border-color 0.2s;
  font-family: inherit;
}

.form-select:focus {
  outline: none;
  border-color: var(--primary-color);
}

/* 响应式 */
@media (min-width: 601px) {
  .container {
    padding: 0 24px;
  }

  .action-buttons {
    flex-direction: row;
  }

  .action-buttons .btn {
    flex: 1;
  }
}