:root{--main: #2563eb;--light: #eff6ff;--warn: #f59e0b;--danger: #ef4444;--success: #10b981;--text: #1f2937;--gray: #6b7280;--bg: #f8fafc}*{margin:0;padding:0;box-sizing:border-box;font-family:Microsoft YaHei,PingFang SC,sans-serif}body{background:var(--bg);color:var(--text);padding-bottom:80px;min-height:100vh;overflow-x:hidden}header{background:var(--main);color:#fff;padding:16px;text-align:center;position:sticky;top:0;z-index:99;box-shadow:0 2px 8px #0000001a}header h1{font-size:18px;margin-bottom:4px}header p{font-size:13px;opacity:.9}.container{padding:12px;max-width:720px;margin:0 auto}.card{background:#fff;border-radius:12px;padding:16px;margin-bottom:12px;box-shadow:0 2px 6px #0000000a}.grade-title{font-size:16px;font-weight:700;color:var(--main);margin:16px 0 8px;display:flex;align-items:center}.grade-title i{margin-right:6px}.unit-list{display:grid;grid-template-columns:1fr 1fr;gap:8px}.unit-item{background:var(--light);border-radius:8px;padding:10px;text-align:center;font-size:14px;color:var(--main);cursor:pointer;transition:all .2s}.unit-item:hover{background:#dbeafe;transform:translateY(-1px)}.page{display:none}.page.active{display:block}.tag{display:inline-block;padding:2px 8px;border-radius:20px;font-size:12px;margin-right:6px}.tag-important{background:#fee2e2;color:var(--danger)}.tag-difficult{background:#fffbeb;color:#d97706}.tag-success{background:#d1fae5;color:var(--success)}.word-list{background:#f0f7ff;border-radius:8px;padding:12px;margin:10px 0}.word-item{display:flex;justify-content:space-between;padding:6px 0;border-bottom:1px dashed #e2e8f0}.word-item:last-child{border-bottom:none}.btn{display:inline-block;padding:8px 16px;border-radius:6px;border:none;cursor:pointer;font-size:14px;margin-right:8px;margin-top:8px;transition:all .2s}.btn:active{transform:scale(.98)}.btn-primary{background:var(--main);color:#fff}.btn-success{background:var(--success);color:#fff}.btn-warning{background:var(--warn);color:#fff}.btn-danger{background:var(--danger);color:#fff}.btn-outline{background:transparent;border:1px solid var(--main);color:var(--main)}.api-tip{background:#fef3f2;border-radius:8px;padding:10px;margin:12px 0;font-size:13px;color:#c53030}.big-title{font-size:17px;font-weight:700;margin:12px 0}.fixed-nav{position:fixed;bottom:0;left:0;right:0;background:#fff;display:flex;border-top:1px solid #eee;z-index:99;padding-bottom:env(safe-area-inset-bottom)}.fixed-nav a{flex:1;text-align:center;padding:12px 4px;font-size:12px;color:var(--gray);text-decoration:none}.fixed-nav a.active{color:var(--main);font-weight:700}.fixed-nav a .nav-icon{font-size:18px;display:block;margin-bottom:2px}.loading{text-align:center;padding:40px;color:var(--gray)}.error-msg{text-align:center;padding:20px;color:var(--danger)}.empty-state{text-align:center;padding:40px 20px;color:var(--gray)}.empty-state .icon{font-size:48px;margin-bottom:12px}@media (max-width: 480px){.unit-list{grid-template-columns:1fr}header h1{font-size:16px}.card{padding:12px;border-radius:8px}}