:root{--bg:#f5f6f8;--surface:#fff;--surface2:#f8fafc;--text:#172033;--muted:#667085;--line:#e4e7ec;--primary:#2457d6;--primary2:#eaf0ff;--danger:#b42318;--success:#067647;--radius:16px;--shadow:0 10px 32px rgba(16,24,40,.12)}*{box-sizing:border-box}body{margin:0;color:var(--text);background:var(--bg);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;line-height:1.55}a{color:inherit;text-decoration:none}button,input,select,textarea{font:inherit}button{cursor:pointer}.app-header{position:sticky;top:0;z-index:20;display:flex;justify-content:space-between;align-items:center;gap:20px;padding:12px 24px;background:rgba(255,255,255,.96);border-bottom:1px solid var(--line)}.brand{font-weight:800}.brand span{font-size:13px;color:var(--muted);font-weight:500}.admin-nav{display:flex;align-items:center;gap:16px;font-size:14px}.admin-nav form{margin:0}.link-button{border:0;background:none;color:var(--primary);padding:0}.admin-shell{max-width:1180px;margin:auto;padding:26px 20px 64px}.admin-shell.narrow{max-width:960px}.date-bar{display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:12px}.date-center{text-align:center}.date-center h1{margin:0;font-size:26px}.date-center p{margin:3px 0;color:var(--muted)}.toolbar{display:flex;flex-wrap:wrap;gap:10px;margin:20px 0}.btn{display:inline-flex;justify-content:center;align-items:center;min-height:42px;padding:8px 15px;border:1px solid var(--line);border-radius:11px;background:#fff;color:var(--text);font-weight:650}.btn.primary{background:var(--primary);border-color:var(--primary);color:#fff}.btn.soft{background:var(--primary2);border-color:transparent;color:var(--primary)}.btn.small{min-height:34px;padding:5px 10px;font-size:13px}.btn.icon{width:42px;padding:0;font-size:20px}.btn.wide{width:100%}.btn.large{min-height:49px}.danger-text{color:var(--danger)}.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);box-shadow:0 2px 10px rgba(16,24,40,.035)}.section{margin-top:28px}.section-heading{display:flex;justify-content:space-between;align-items:end;gap:12px;margin-bottom:12px}.section-heading h2{margin:0;font-size:20px}.section-heading span{font-size:13px;color:var(--muted)}.stack{display:grid;gap:13px}.group-card,.edit-card,.form-card{padding:18px}.group-head h3,.group-head p{margin:0}.group-head p{color:var(--muted);font-size:13px}.assignment-row{display:grid;grid-template-columns:32px minmax(0,1fr) auto;gap:10px;align-items:center;padding:12px 0;border-top:1px solid var(--line)}.assignment-row:first-of-type{margin-top:8px}.order-no{display:grid;place-items:center;width:27px;height:27px;border-radius:8px;background:var(--surface2);color:var(--muted);font-size:13px;font-weight:700}.assignment-main strong{display:block}.assignment-main small{color:var(--muted)}.row-actions{display:flex;gap:5px;align-items:center}.row-actions form{margin:0}.exception-card{display:flex;justify-content:space-between;align-items:center;gap:14px;padding:14px 16px}.exception-card strong{display:block}.exception-card p{margin:2px 0;color:var(--muted)}.exception-card.exempt{border-left:4px solid #d92d20}.empty-state{padding:28px;text-align:center;border:1px dashed #cfd5df;border-radius:var(--radius);color:var(--muted);background:rgba(255,255,255,.55)}.notice{padding:11px 14px;border-radius:11px;background:var(--surface2);border:1px solid var(--line);margin-bottom:16px}.notice.success{color:var(--success);background:#ecfdf3;border-color:#abefc6}.notice.danger{color:var(--danger);background:#fff1f0;border-color:#ffd5d2}.modal{width:min(680px,calc(100% - 28px));max-height:calc(100vh - 36px);padding:0;border:0;border-radius:18px;box-shadow:var(--shadow)}.modal::backdrop{background:rgba(16,24,40,.55)}.small-modal{max-width:480px}.modal-head,.modal-foot{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:16px 20px}.modal-head{position:sticky;top:0;background:#fff;border-bottom:1px solid var(--line)}.modal-head h2{margin:0}.modal-body{padding:20px;overflow:auto}.modal-foot{justify-content:flex-end;border-top:1px solid var(--line);background:var(--surface2)}.form-stack{display:grid;gap:15px}.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px}.span-2{grid-column:1/-1}label,.field-label{display:grid;gap:6px;font-size:14px;font-weight:700}input,select,textarea{width:100%;min-height:43px;padding:9px 11px;border:1px solid #cfd5df;border-radius:10px;background:#fff;color:var(--text)}textarea{min-height:82px;resize:vertical}fieldset{border:1px solid var(--line);border-radius:12px;padding:13px}legend{font-weight:700}.target-grid{display:grid;grid-template-columns:1fr 1fr;gap:8px}.check-card{display:flex;align-items:center;gap:8px;padding:10px;border:1px solid var(--line);border-radius:10px;background:var(--surface2);font-weight:500}.check-card input{width:auto;min-height:auto}.preview-panel{padding:14px;border:1px solid var(--line);border-radius:12px}.preview-panel h3{margin-top:0}.preview-item{padding:10px 0;border-top:1px solid var(--line)}.preview-item:first-of-type{border-top:0}.preview-item strong,.preview-item small{display:block}.preview-item small{color:var(--muted)}.page-heading h1{margin-bottom:0}.page-heading p{margin-top:4px;color:var(--muted)}.inline-form{display:flex;align-items:end;gap:12px}.inline-form>*{flex:1}.inline-form button{flex:0 0 auto}.inline-form.compact{border-bottom:1px solid var(--line);padding-bottom:16px}.member-form{margin-top:16px}.member-form h3{margin-top:0}.right{text-align:right}.muted{color:var(--muted)}.center-shell{min-height:100vh;display:grid;place-items:center;padding:20px}.login-card,.bind-card{width:min(100%,460px);padding:28px}.login-card h1,.bind-card h1{margin:0 0 8px}.eyebrow{margin:0;color:var(--primary);font-weight:800;font-size:13px;letter-spacing:.08em}.parent-shell{width:min(100%,640px);margin:auto;padding:24px 16px 60px}.center-parent{min-height:100vh;display:grid;place-items:center}.parent-top{display:flex;justify-content:space-between;align-items:start;margin-bottom:16px}.student-details summary{font-size:18px;font-weight:800;cursor:pointer;list-style:none}.student-menu-card{position:absolute;z-index:5;margin-top:8px;padding:14px;background:#fff;border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow)}.student-menu-card p{margin:0 0 8px;color:var(--muted)}.hero-card{padding:22px;margin-bottom:16px;background:linear-gradient(145deg,#fff,#f3f7ff)}.hero-card h1{margin:0}.hero-card p{margin:5px 0 0;color:var(--muted)}.homework-card{padding:19px}.subject{display:inline-flex;padding:3px 9px;border-radius:999px;background:var(--primary2);color:var(--primary);font-size:13px;font-weight:750}.homework-card h2{margin:12px 0 5px;font-size:20px}.homework-card p{color:#475467}.meta{font-size:13px;color:var(--muted);margin-bottom:14px}.empty-homework{text-align:center}.course-shell{width:min(100%,760px);margin:auto;padding:18px 16px 70px}.back-link{display:inline-block;color:var(--primary);font-weight:700;margin-bottom:14px}.course-shell>h1{margin:0}.lesson-section{padding:20px;margin-top:18px}.lesson-section h2{margin:0 0 14px}.english{font-size:18px;line-height:1.8}.translation{padding:12px;background:var(--surface2);border-radius:10px;color:#475467}.sentence-card{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:13px 0;border-top:1px solid var(--line)}.sentence-card:first-of-type{border-top:0}.sentence-card p{margin:2px 0}.word-list{display:grid;gap:10px}.word-list>div{padding:13px;background:var(--surface2);border-radius:11px}.word-list p{margin:4px 0 0;color:#475467}@media(max-width:760px){.app-header{align-items:flex-start;padding:10px 14px}.admin-nav{flex-wrap:wrap;justify-content:flex-end;gap:9px}.admin-shell{padding:18px 12px 50px}.date-center h1{font-size:20px}.assignment-row{grid-template-columns:29px 1fr}.row-actions{grid-column:2;flex-wrap:wrap}.exception-card{align-items:flex-start}.form-grid,.target-grid{grid-template-columns:1fr}.span-2{grid-column:auto}.inline-form{display:grid;align-items:stretch}.modal{width:100%;max-height:92vh;margin:auto 0 0;border-radius:18px 18px 0 0}.sentence-card{display:block}.sentence-card .btn{width:100%;margin-top:8px}}