:root{--bg:#f7f8f5;--paper:#fff;--ink:#253d36;--muted:#818b85;--green:#236b5b;--light:#edf4ee;--line:#e6eae4;--orange:#c17b48;--red:#ac544b;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;color:var(--ink);background:var(--bg);font-synthesis:none}*{box-sizing:border-box}body{margin:0}button,input,select{font:inherit}button,a,input,select{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.46}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #8cbead;outline-offset:3px}button{color:inherit}a{color:var(--green)}[hidden]{display:none!important}.app-shell{display:flex;min-height:100vh}.sidebar{position:fixed;inset:0 auto 0 0;width:235px;background:#fff;border-right:1px solid var(--line);padding:36px 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@media(min-width:1450px){.main-content{padding-top:48px}.question-card{padding:33px}.study-layout{grid-template-columns:minmax(0,1fr) 275px;gap:28px}}
@media(max-width:1150px){.sidebar{width:195px;padding:30px 18px}main{margin-left:195px}.main-content{padding:30px 26px}.topbar{padding:0 26px}.study-layout{grid-template-columns:minmax(0,1fr) 225px;gap:17px}.question-card{padding:22px}.keyboard-hint{display:none}h1{font-size:25px}.review-card{padding:18px 14px}.search-controls input{width:150px}}
@media(max-width:900px){.study-layout{grid-template-columns:1fr}.study-aside{display:grid;grid-template-columns:1fr 1fr;gap:20px}.gentle-note{display:none}.recent-card{padding-top:16px}.stat-strip>div{padding:0 18px}.mistakes-toolbar{flex-wrap:wrap}.search-controls{flex:1}.search-controls input{width:100%}.heading-seal{display:none}}
@media(max-width:620px){.app-shell{display:block}.sidebar{position:static;width:100%;padding:17px 20px 0;border-right:0;border-bottom:1px solid var(--line)}.brand{font-size:22px;gap:10px}.brand-mark{width:35px;height:37px;font-size:18px;border-radius:10px}.brand small{font-size:9px}.course-label,.sidebar-course,.sidebar-bottom,.nav-arrow{display:none}.sidebar nav{display:flex;gap:12px;margin-top:18px}.nav-item{justify-content:center;font-size:13px;padding:12px;margin-bottom:0;border-radius:7px 7px 0 0}.nav-symbol{font-size:17px}.nav-count{margin-left:0}main{margin-left:0}.topbar{height:44px;padding:0 20px;font-size:10px}.save-status{font-size:10px}.main-content{padding:26px 17px 18px}.page-heading{margin-bottom:22px}.eyebrow{font-size:9px;margin-bottom:10px}h1{font-size:23px}.page-heading p{font-size:11px}.stat-strip{padding:17px 0;border-radius:9px;margin-bottom:22px}.stat-strip>div{padding:0 12px}.stat-strip span{font-size:10px;margin-bottom:8px}.stat-strip strong{font-size:21px}.stat-strip small{font-size:9px;margin-left:3px}.question-card{padding:21px 17px;border-radius:11px}.question-top{gap:8px}.question-number{font-size:9px}h2#question-stem{font-size:17px;line-height:1.85;margin-top:24px}.choice-help{margin-bottom:18px}.option{font-size:13px;padding:12px;gap:11px}.option-letter{width:27px;height:27px}.question-footer{margin-top:23px;padding-top:19px}.question-footer .button{width:100%;min-height:46px}.study-aside{grid-template-columns:1fr}.review-card{padding:21px}.review-steps{display:none}.review-card>p{margin:12px 0 16px}.review-card .button{width:auto;min-height:35px}.review-card .mode-caption{display:inline-block;margin-left:10px;max-width:155px;text-align:left;vertical-align:middle}.recent-card{padding:0 4px}.mistakes-toolbar{gap:12px}.search-controls{width:100%;flex:auto}.search-controls select{max-width:135px}.wrong-item{padding:19px 16px}.wrong-item h3{font-size:14px}.wrong-item-footer{font-size:10px}.mistakes-bottom{align-items:flex-start;flex-direction:column;line-height:1.8}.mistakes-bottom .button{width:100%}.page-footer{font-size:8px}.storage-warning{padding:14px 20px}.feedback{padding:15px}.filter-tabs{width:100%}.filter-tabs button{flex:1}}
.nav-item{white-space:nowrap;gap:10px}.nav-count{font-size:10px;padding:2px 5px}.source-caption .text-button{font-size:9px;margin-left:8px}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}
.login-required{background:#eef3ec}.login-gate{min-height:100vh;display:grid;place-items:center;padding:24px}.login-card{width:min(410px,100%);padding:34px;background:white;border:1px solid var(--line);border-radius:17px;box-shadow:0 20px 70px #25403314}.login-brand{display:flex;gap:12px;align-items:center;font-size:23px;letter-spacing:3px;font-weight:650}.login-brand small{display:block;color:var(--muted);font-size:10px;letter-spacing:1px;font-weight:400;margin-top:5px}.login-card h1{font-size:26px;margin:35px 0 7px}.login-card p{font-size:12px;color:var(--muted);line-height:1.8;margin:0 0 27px}.login-card label{display:block;font-size:12px;color:#607568;margin:18px 0}.login-card input{display:block;width:100%;margin-top:8px;padding:13px 12px;border:1px solid #dce6dc;border-radius:7px;background:#fcfdfb;font-size:15px}.login-card .button{width:100%;margin-top:10px;font-size:13px}.login-error{min-height:20px;color:#ad544b;font-size:11px}