/* 全局样式 */
body { font-family: 'Helvetica Neue', Arial, sans-serif; margin: 0; padding: 0; background-color: #f5f6fa; color: #333; }
h2, h3 { margin-top: 0; }

/* 登录样式 */
.login-container { width: 350px; margin: 100px auto; padding: 30px; background: white; border-radius: 8px; box-shadow: 0 4px 15px rgba(0,0,0,0.1); text-align: center; }
.login-container input { width: 100%; padding: 10px; margin: 10px 0; box-sizing: border-box; border: 1px solid #ddd; border-radius: 4px; }
.login-container button { width: 45%; padding: 10px; margin: 5px; border: none; border-radius: 4px; cursor: pointer; background-color: #3498db; color: white; }

/* 学生端主页网格化/分栏布局 */
.navbar { background-color: #2c3e50; color: white; padding: 15px 30px; display: flex; justify-content: space-between; align-items: center; }
.btn-logout { background-color: #e74c3c; color: white; border: none; padding: 5px 10px; border-radius: 4px; cursor: pointer; }
.container { display: flex; min-height: calc(100vh - 60px); }
.sidebar { width: 220px; background-color: #34495e; padding: 20px 10px; box-sizing: border-box; }
.tab-btn { width: 100%; background: none; border: none; color: #ecf0f1; padding: 12px; text-align: left; font-size: 16px; cursor: pointer; border-radius: 4px; margin-bottom: 5px; }
.tab-btn.active, .tab-btn:hover { background-color: #3498db; color: white; }
.content { flex: 1; padding: 30px; box-sizing: border-box; }

/* 标签页控制显示/隐藏 */
.tab-content { display: none; }
.tab-content.active { display: block; }

/* 卡片布局（活动、证书网格） */
.grid-container { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; margin-top: 20px; }
.card { background: white; padding: 20px; border-radius: 8px; box-shadow: 0 2px 8px rgba(0,0,0,0.05); border-left: 5px solid #3498db; position: relative; }
.card button { width: 100%; padding: 8px; border: none; border-radius: 4px; cursor: pointer; margin-top: 10px; font-weight: bold; }

/* 按钮颜色配置 */
.btn-success { background-color: #2ecc71; color: white; }
.btn-danger { background-color: #e74c3c; color: white; }
.btn-disabled { background-color: #bdc3c7; color: #7f8c8d; cursor: not-allowed; }

/* 证书卡片样式 */
.certificate-card { border-left: 5px solid #d4af37; background: #fffdf3; }
.cert-border { border: 2px dashed #d4af37; padding: 15px; border-radius: 4px; }
.cert-footer { margin-top: 20px; font-size: 12px; color: #7f8c8d; text-align: right; }
/* 后台表单和表格样式 */
.form-container { background: white; padding: 30px; border-radius: 8px; box-shadow: 0 2px 8px rgba(0,0,0,0.05); max-width: 500px; }
.form-group { margin-bottom: 15px; }
.form-group label { display: block; margin-bottom: 5px; font-weight: bold; }
.form-group input { width: 100%; padding: 10px; border: 1px solid #ccc; border-radius: 4px; box-sizing: border-box; }

.data-table { width: 100%; border-collapse: collapse; background: white; margin-top: 10px; box-shadow: 0 2px 8px rgba(0,0,0,0.05); }
.data-table th, .data-table td { padding: 12px; border: 1px solid #eee; text-align: left; }
.data-table th { background-color: #f8f9fa; font-weight: bold; }
.data-table tr:hover { background-color: #f1f2f6; }