:root{--app-bg:#f4f7fb;--app-surface:#fff;--app-surface-soft:#f8fafc;--app-border:#dfe7f1;--app-border-strong:#cbd8e8;--app-text:#172033;--app-text-muted:#667085;--app-text-soft:#98a2b3;--app-primary:#2f7df6;--app-primary-strong:#1f63d8;--app-primary-soft:#eaf2ff;--app-success:#16a36a;--app-success-soft:#e9f8f0;--app-warning:#d98916;--app-warning-soft:#fff4df;--app-danger:#e5484d;--app-danger-soft:#fff0f0;--app-info:#667085;--app-info-soft:#eef2f7;--app-radius-sm:8px;--app-radius:10px;--app-radius-lg:14px;--app-shadow-sm:0 1px 2px #1018280d;--app-shadow:0 10px 30px #10182814;--app-page-max:1120px;--app-page-gutter:24px;--el-color-primary:var(--app-primary);--el-color-success:var(--app-success);--el-color-warning:var(--app-warning);--el-color-danger:var(--app-danger);--el-border-radius-base:var(--app-radius-sm);--el-border-color:var(--app-border);--el-text-color-primary:var(--app-text);--el-text-color-regular:var(--app-text-muted)}*{box-sizing:border-box}html,body,#app{min-height:100%}body{background:var(--app-bg);color:var(--app-text);margin:0;font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,PingFang SC,Microsoft YaHei,sans-serif;overflow-x:hidden}button,input,textarea,select{font:inherit}a{color:inherit}.app-page{width:100%;max-width:var(--app-page-max);margin:0 auto}.app-page-narrow{max-width:920px}.app-stack{flex-direction:column;gap:18px;display:flex}.app-grid{gap:16px;display:grid}.app-grid-2{grid-template-columns:repeat(2,minmax(0,1fr))}.app-grid-3{grid-template-columns:repeat(3,minmax(0,1fr))}.app-card{background:var(--app-surface);border:1px solid var(--app-border);border-radius:var(--app-radius);box-shadow:var(--app-shadow-sm)}.app-section-title{color:var(--app-text);margin:0;font-size:17px;font-weight:700;line-height:1.35}.app-section-subtitle{color:var(--app-text-muted);margin:4px 0 0;font-size:13px;line-height:1.6}.app-muted{color:var(--app-text-muted)}.app-actions{flex-wrap:wrap;align-items:center;gap:10px;display:flex}.el-card{border-color:var(--app-border);border-radius:var(--app-radius);box-shadow:var(--app-shadow-sm)}.el-card__header{border-bottom-color:var(--app-border);padding:16px 20px;font-weight:700}.el-card__body{padding:20px}.el-button{min-height:36px;font-weight:650}.el-button--large{min-height:44px}.el-button+.el-button{margin-left:0}.el-input__wrapper,.el-select__wrapper,.el-textarea__inner{box-shadow:0 0 0 1px var(--app-border) inset}.el-input__wrapper:hover,.el-select__wrapper:hover,.el-textarea__inner:hover{box-shadow:0 0 0 1px var(--app-border-strong) inset}.el-tag{border-radius:999px;font-weight:650}.student-empty{padding:40px 16px}@media (width<=768px){:root{--app-page-gutter:12px}.app-grid-2,.app-grid-3{grid-template-columns:1fr}.el-card__header{padding:14px 16px}.el-card__body{padding:16px}}#app-container{flex-direction:column;min-height:100dvh;display:flex;overflow-x:hidden}.app-header{padding:0 var(--app-page-gutter);border-bottom:1px solid var(--app-border);box-shadow:var(--app-shadow-sm);z-index:100;-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);background:#ffffffeb;position:sticky;top:0;height:64px!important}.header-shell{justify-content:space-between;align-items:center;gap:18px;max-width:1360px;height:100%;margin:0 auto;display:flex}.header-nav{flex:auto;justify-content:flex-start;align-items:center;gap:4px;min-width:0;display:flex}.nav-item{color:var(--app-text-muted);border-radius:999px;flex:none;align-items:center;gap:6px;padding:9px 13px;font-size:14px;font-weight:650;text-decoration:none;transition:color .18s,background-color .18s;display:flex}.nav-item:hover,.nav-active{color:var(--app-primary);background:var(--app-primary-soft)}.header-utils{align-items:center;gap:8px;display:flex}.utility-button,.mobile-more-button{min-height:36px;color:var(--app-text-muted);background:var(--app-surface);border:1px solid var(--app-border);cursor:pointer;border-radius:999px;justify-content:center;align-items:center;gap:6px;padding:0 12px;transition:color .18s,border-color .18s,background-color .18s;display:inline-flex}.utility-button:hover,.mobile-more-button:hover{color:var(--app-primary);background:var(--app-primary-soft);border-color:var(--app-primary)}.mobile-more{display:none}.app-main{width:100%;max-width:100%;padding:24px var(--app-page-gutter) 32px;flex:1;overflow-y:auto}.app-alert{max-width:var(--app-page-max);margin:0 auto 16px}.app-loading{min-height:260px;color:var(--app-text-muted);justify-content:center;align-items:center;gap:10px;display:flex}.admin-summary{flex-wrap:wrap;align-items:flex-end;gap:24px;display:flex}.admin-tip{color:var(--app-text-soft);padding-bottom:4px;font-size:13px}.admin-section-title{color:var(--app-text);margin:0 0 12px;font-size:15px}.admin-table-wrap{width:100%;overflow-x:auto}.device-cell{gap:3px;min-width:0;display:grid}.device-title{color:var(--app-text);font-weight:700;line-height:1.35}.device-sub,.device-user-agent{color:var(--app-text-soft);font-size:12px;line-height:1.35}.device-user-agent{white-space:nowrap;text-overflow:ellipsis;max-width:360px;overflow:hidden}.feedback-list{flex-direction:column;gap:10px;max-height:420px;display:flex;overflow-y:auto}.feedback-item{background:var(--app-surface);border:1px solid var(--app-border);border-radius:var(--app-radius-sm);padding:12px}.feedback-meta{color:var(--app-text-soft);flex-wrap:wrap;gap:10px;margin-bottom:8px;font-size:12px;display:flex}.feedback-content{color:var(--app-text);white-space:pre-wrap;overflow-wrap:anywhere;font-size:14px;line-height:1.6}.mobile-tabbar{display:none}@media (width<=768px){.app-header{height:58px!important}.header-shell{gap:10px}.header-nav,.header-utils{display:none}.mobile-more{margin-left:auto;display:block}.mobile-more-button{width:38px;padding:0}.app-main{padding:16px var(--app-page-gutter) calc(92px + env(safe-area-inset-bottom))}.mobile-tabbar{z-index:120;padding:8px 8px calc(8px + env(safe-area-inset-bottom));border-top:1px solid var(--app-border);-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);background:#fffffff5;grid-template-columns:repeat(5,minmax(0,1fr));gap:2px;display:grid;position:fixed;bottom:0;left:0;right:0;box-shadow:0 -10px 30px #10182814}.mobile-tab{min-width:0;min-height:52px;color:var(--app-text-muted);border-radius:12px;place-items:center;gap:3px;font-size:12px;font-weight:700;text-decoration:none;display:grid}.mobile-tab .el-icon{font-size:18px}.mobile-tab-active{color:var(--app-primary);background:var(--app-primary-soft)}}