/* LearnUp V2 统一界面（2026-09-26）：一屏一重点；顶栏与底栏固定；手机 390×844 与平板 768×1024 必须整屏看完 */
:root{--v2-top:64px;--v2-bottom:76px;--v2-green:#177a55;--v2-green2:#38a978;--v2-line:#cce5d8;--v2-ink:#193f32}
html,body{height:100%}body:has(.v2-main){overflow:hidden}
.v2-top{position:fixed;z-index:20;top:0;left:0;right:0;height:var(--v2-top);display:flex;align-items:center;gap:8px;padding:8px max(12px,env(safe-area-inset-left));background:#fff;border-bottom:1px solid #deeee6}
.v2-back{flex:none;display:inline-flex;align-items:center;min-height:44px;padding:0 14px;border-radius:12px;background:var(--v2-green);color:#fff!important;font-weight:900;text-decoration:none;font-size:15px}
.v2-title{flex:1;min-width:0}.v2-title b{display:block;font-size:15px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--v2-ink)}
.v2-bar{height:6px;border-radius:6px;background:#e3f1ea;margin-top:5px;overflow:hidden}.v2-bar i{display:block;height:100%;background:linear-gradient(90deg,var(--v2-green),var(--v2-green2));transition:width .3s}
.v2-count{flex:none;font-weight:900;color:var(--v2-green);font-size:14px}
.v2-lang{flex:none;min-height:44px;padding:0 14px;border:2px solid #a9d7c2;border-radius:12px;background:#fff;color:var(--v2-green);font:inherit;font-weight:900;font-size:15px;cursor:pointer}
.v2-lang[disabled]{opacity:.35;cursor:default}
.v2-main{position:fixed;top:var(--v2-top);bottom:var(--v2-bottom);left:0;right:0;overflow-y:auto;-webkit-overflow-scrolling:touch}
.v2-main .screen{min-height:100%!important;padding:16px clamp(14px,4vw,48px) 20px!important;justify-content:center}
.v2-nav{position:fixed;z-index:20;left:0;right:0;bottom:0;height:var(--v2-bottom);display:flex;align-items:center;gap:12px;padding:10px 14px calc(10px + env(safe-area-inset-bottom));background:#f1faf5;border-top:1px solid #d8ebe1}
.v2-nav .btn{flex:1;max-width:260px;min-height:56px;font-size:18px;white-space:nowrap;padding:10px 12px}.v2-nav .grow{flex:1}
.v2-sheet{position:fixed;inset:0;z-index:40;background:#0b2a1f66;display:flex;align-items:flex-end;justify-content:center}
.v2-sheet[hidden]{display:none}
.v2-panel{width:min(720px,100%);max-height:78vh;overflow:auto;background:#fff;border-radius:22px 22px 0 0;padding:18px 20px calc(18px + env(safe-area-inset-bottom));box-shadow:0 -10px 30px #0003}
.v2-panel h3{margin:0 0 10px;color:var(--v2-green);font-size:18px}.v2-panel .body{white-space:pre-line;line-height:1.75;font-size:17px;color:#2d4a3f}
.v2-panel .row{margin-top:14px;justify-content:space-between}
.v2-drawer-src{display:none}
@media(min-width:900px){.v2-sheet{align-items:center}.v2-panel{border-radius:22px}}
@media(max-width:700px){:root{--v2-top:96px}.v2-top{flex-wrap:wrap;height:auto;min-height:var(--v2-top);padding:8px 10px}.v2-title{order:5;flex-basis:100%}.v2-count{margin-left:auto}.v2-lang,.v2-back{min-height:40px;padding:0 10px;font-size:14px}
 .v2-main .title{font-size:28px!important;margin:6px 0!important}.v2-main .subtitle{font-size:15px;margin-bottom:10px}.v2-main .card{padding:14px}.v2-main .number{font-size:56px}.v2-main .words{font-size:20px}.v2-main .hero{max-height:120px;width:auto!important;margin:4px 0 10px}.v2-main .option,.v2-main .match{min-height:56px;font-size:20px;padding:10px}.v2-main .options{gap:8px;margin-top:12px}}
@media(max-height:700px){.v2-main .hero{display:none}}
/* 紧凑化：保证一屏看完 */
.v2-main .number{font-size:clamp(52px,9vw,84px)}.v2-main .card{padding:clamp(12px,2vw,20px)}.v2-main .words{margin:8px 0 4px}.v2-main .place-grid{margin:10px auto}.v2-main .place{padding:8px 6px}.v2-main .place strong{font-size:26px}
.v2-main .zero{padding:12px}.v2-main .zero b{font-size:32px}.v2-main .zero strong{font-size:17px;margin:4px 0}.v2-main .zero .btn{min-height:40px;padding:6px 14px}
.v2-main .zero-list{gap:10px;margin:10px auto}.v2-main .title{margin:6px 0}
.rod{min-height:110px}
@media(max-width:700px){
 .v2-main .screen{padding-top:10px!important}
 .v2-main .zero-list{grid-template-columns:repeat(2,minmax(0,1fr))!important;gap:8px}.v2-main .zero{padding:8px}.v2-main .zero b{font-size:24px}.v2-main .zero strong{font-size:14px}.v2-main .wrong-read{font-size:12px}.v2-main .zero .btn{min-height:36px;font-size:13px;padding:4px 10px}
 .forms{grid-template-columns:1fr 1fr!important;gap:8px!important}.forms .form{padding:8px}.forms .form:last-child{grid-column:1/-1}.calc{min-width:0;font-size:26px;padding:10px}.rod{min-height:84px}.bead{height:10px}.abacus{grid-template-columns:repeat(4,30px)!important;gap:3px;padding:8px}.bead{width:24px}.wordcard{font-size:17px}
 .v2-main .match-board{grid-template-columns:1fr 1fr!important;gap:8px;margin-top:10px}.v2-main .match{min-height:54px;font-size:15px;padding:6px}
 .tiles{gap:6px;margin:8px 0}.tile{min-height:46px;padding:6px 10px;font-size:16px}.answer-line{min-height:48px;font-size:19px;padding:8px}
 .check-cards{grid-template-columns:1fr!important;gap:6px}.check-cards .option{min-height:0;padding:6px}.check-cards .option b{font-size:22px}
 .v2-main .btn.audio{min-height:40px;padding:6px 14px;font-size:14px}.v2-main .subtitle{font-size:14px;line-height:1.4;margin:0 0 6px}
 .v2-main .practice-card{padding:12px;margin-top:0}.v2-main .practice-question{font-size:19px;margin:8px 0 4px}
}
.v2-main .practice-question{margin:12px 0 6px}.v2-main .practice-card{margin-top:0}
.forms .form{min-width:0;overflow:hidden}
.v2-main .eyebrow,.eyebrow{text-transform:none;letter-spacing:.02em;font-size:15px}