*{box-sizing:border-box}html{-webkit-text-size-adjust:100%;text-size-adjust:100%;touch-action:manipulation}body{touch-action:manipulation;-webkit-user-select:none;user-select:none;overflow-x:hidden}html,body{margin:0;min-height:100%;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB",Arial,sans-serif;background:var(--bg);color:var(--text)}body{min-height:100dvh;overscroll-behavior:none}button{font:inherit;color:inherit;border:0;cursor:pointer;-webkit-tap-highlight-color:transparent}button:disabled{cursor:default}.app{min-height:100dvh;background:var(--bg);padding:max(0px,env(safe-area-inset-top)) max(14px,env(safe-area-inset-right)) max(14px,env(safe-area-inset-bottom)) max(14px,env(safe-area-inset-left));--bg:#f5f6f8;--card:#ffffff;--text:#17202a;--muted:#7b8490;--line:rgba(127,127,127,.16);--accent:#2aabee;--accent-text:#ffffff;--soft:rgba(42,171,238,.11)}.screen{display:none;max-width:560px;margin:0 auto;min-height:calc(100dvh - env(safe-area-inset-top) - env(safe-area-inset-bottom));padding:24px 0 26px}.screen.active{display:flex;flex-direction:column}.home-head{text-align:center;padding:38px 0 32px}.brand-icon{font-size:56px;line-height:1;margin-bottom:12px}.home-head h1{margin:0;font-size:38px;letter-spacing:1px}.home-head p{margin:8px 0 0;color:var(--muted);font-size:15px}.mode-list{display:grid;gap:14px}.mode-card{display:flex;align-items:center;text-align:left;gap:14px;width:100%;padding:20px;border:1px solid var(--line);background:var(--card);border-radius:20px;box-shadow:0 5px 18px rgba(0,0,0,.045);transition:transform .12s}.mode-card:active,.difficulty-card:active,.primary-btn:active,.submit-btn:active{transform:scale(.985)}.mode-icon{font-size:29px}.mode-copy{display:grid;gap:5px;flex:1}.mode-copy strong{font-size:18px}.mode-copy small,.difficulty-card small{color:var(--muted);font-size:13px}.chevron{font-size:28px;color:var(--muted)}.records-link{margin:25px auto 0;background:none;color:var(--accent);font-weight:650}.home-note{margin:18px auto 0;color:var(--muted);font-size:12px;text-align:center}.sub-header,.game-header{height:48px;display:grid;grid-template-columns:48px 1fr 48px;align-items:center;margin-bottom:10px}.sub-header h2,.game-title{text-align:center;font-size:17px;margin:0}.icon-btn{width:44px;height:44px;background:none;font-size:32px;line-height:1;border-radius:14px}.icon-btn:active{background:var(--soft)}.difficulty-wrap{padding-top:28px}.difficulty-wrap h3{font-size:27px;margin:0 0 7px}.difficulty-wrap>p{margin:0 0 22px;color:var(--muted)}.difficulty-list{display:grid;gap:12px}.difficulty-card{display:flex;align-items:center;gap:13px;width:100%;padding:17px;border:2px solid var(--line);border-radius:18px;background:var(--card);text-align:left}.difficulty-card.selected{border-color:var(--accent);background:var(--soft)}.difficulty-card>span{font-size:20px}.difficulty-card div{display:grid;gap:4px;flex:1}.difficulty-card b{opacity:0;color:var(--accent)}.difficulty-card.selected b{opacity:1}.primary-btn,.submit-btn{width:100%;border-radius:16px;padding:15px;margin-top:22px;background:var(--accent);color:var(--accent-text);font-weight:750;font-size:16px}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin:2px 0 16px}.stats>div{background:var(--card);border:1px solid var(--line);border-radius:14px;text-align:center;padding:9px 5px}.stats small{display:block;color:var(--muted);font-size:11px;margin-bottom:3px}.stats strong{font-size:20px}.stats .hidden{display:none}.problem{background:var(--card);border:1px solid var(--line);border-radius:22px;padding:17px 14px 15px;box-shadow:0 5px 18px rgba(0,0,0,.04)}.number-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:9px}.number-card{min-height:74px;border-radius:16px;background:var(--soft);border:1px solid var(--line);font-size:29px;font-weight:800}.number-card.used{background:rgba(127,127,127,.12);color:var(--muted);opacity:.65}.expression{min-height:83px;margin-top:15px;border-radius:15px;background:rgba(127,127,127,.07);display:flex;align-items:center;justify-content:center;padding:10px;font-size:28px;font-weight:750;word-break:break-word;text-align:center;line-height:1.3}.placeholder{font-size:14px;color:var(--muted);font-weight:500}.result-message{text-align:center;min-height:22px;padding-top:7px;font-size:13px;font-weight:650}.result-message.ok{color:#18a058}.result-message.bad{color:#d9534f}.keypad{margin-top:12px}.number-pad{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.number-pad button,.operator-pad button,.edit-pad button,.helper-row button{min-height:49px;border-radius:14px;background:var(--card);border:1px solid var(--line);font-weight:700}.number-pad button{font-size:19px}.number-pad button.used{color:var(--muted);background:rgba(127,127,127,.1)}.operator-pad{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:8px}.operator-pad button{font-size:22px}.edit-pad{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:8px}.edit-pad button{font-size:17px}.submit-btn{margin-top:10px}.submit-btn:disabled{background:rgba(127,127,127,.18);color:var(--muted)}.helper-row{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-top:8px}.helper-row button{background:none;color:var(--accent);font-size:13px;min-height:43px}.records{padding-top:16px}.records h3{font-size:17px;margin:20px 0 10px}.record-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:9px}.record-grid>div,.timed-record{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:13px}.record-grid span,.record-grid small,.record-grid b{display:block}.record-grid span{font-size:13px}.record-grid strong{display:block;font-size:29px;margin:8px 0 0}.record-grid small{color:var(--muted);font-size:11px}.record-grid b{font-size:11px;color:var(--muted);margin-top:7px}.record-grid i{font-style:normal;color:var(--text)}.timed-note{margin:-4px 0 10px;color:var(--muted);font-size:12px}.timed-record{display:grid;grid-template-columns:1fr 1fr;text-align:center}.timed-record div+div{border-left:1px solid var(--line)}.timed-record span{display:block;color:var(--muted);font-size:12px}.timed-record strong{font-size:36px}.secondary-btn{margin:24px auto 0;display:block;background:none;color:var(--muted);font-size:12px}.overlay{position:fixed;inset:0;background:rgba(0,0,0,.42);display:flex;align-items:center;justify-content:center;padding:20px;z-index:20}.overlay.hidden{display:none}.modal{width:min(420px,100%);background:var(--card);border-radius:22px;padding:24px;box-shadow:0 18px 50px rgba(0,0,0,.22);text-align:center}.modal h3{margin:0;font-size:22px}.modal p{color:var(--muted);white-space:pre-line;line-height:1.55}.modal-buttons{display:grid;gap:9px;margin-top:18px}.modal-buttons button{min-height:46px;border-radius:14px;background:var(--soft);color:var(--accent);font-weight:700}@media(max-width:390px){.number-card{min-height:65px}.expression{font-size:24px}.record-grid{grid-template-columns:1fr}}
/* V1 精修：题目区与操作区明确分离 */
.number-grid{position:relative}
.number-card{display:flex;align-items:center;justify-content:center;user-select:none;transition:all .16s ease}
.number-card.used{transform:scale(.96);text-decoration:line-through;text-decoration-thickness:2px}
.number-card.used::after{content:"已用";position:absolute;font-size:10px;font-weight:650;color:var(--muted);margin-top:45px;text-decoration:none}
.number-pad button{position:relative;transition:transform .1s ease,opacity .15s ease,background .15s ease}
.number-pad button:not(:disabled):active{transform:scale(.96)}
.number-pad button.used{opacity:.42;text-decoration:line-through}
.number-pad button.used::after{content:"已用";position:absolute;right:7px;bottom:5px;font-size:9px;font-weight:500;color:var(--muted);text-decoration:none}
.number-pad{grid-template-columns:repeat(4,minmax(0,1fr))}
.operator-pad button:disabled,.edit-pad button:disabled{opacity:.38}
.problem::before{content:"题目";display:block;color:var(--muted);font-size:11px;font-weight:650;letter-spacing:.08em;margin:0 0 8px 3px}
.expression{font-variant-numeric:tabular-nums;letter-spacing:.01em}
.result-message{transition:opacity .15s ease,transform .15s ease}
.result-message.ok{animation:answerOk .25s ease}
@keyframes answerOk{0%{transform:scale(.97);opacity:.5}100%{transform:scale(1);opacity:1}}
.timer-stat strong{font-variant-numeric:tabular-nums}
@media(max-width:390px){
  .number-card{min-height:62px;font-size:26px}
  .number-card.used::after{margin-top:40px}
  .number-pad button{min-height:47px}
}

/* Telegram Mini App 精修 */
html,body{width:100%;overflow-x:hidden}
button{touch-action:manipulation}
.app{width:100%;min-height:100dvh;overflow-x:hidden}
.screen{width:100%;padding-top:max(10px,env(safe-area-inset-top));padding-bottom:max(18px,env(safe-area-inset-bottom))}
.stats.timed-layout{grid-template-columns:repeat(4,minmax(0,1fr))}
.timer-stat.urgent{background:rgba(217,83,79,.10);border-color:rgba(217,83,79,.28)}
.timer-stat.urgent strong{color:#d9534f}
@media(max-width:430px){
  .screen{padding-left:0;padding-right:0}
  .home-head{padding-top:28px;padding-bottom:26px}
  .brand-icon{font-size:50px}
  .home-head h1{font-size:34px}
  .mode-card{padding:17px;border-radius:18px}
  .problem{padding:14px 12px 13px;border-radius:20px}
  .number-card{min-height:66px}
  .expression{min-height:76px;font-size:26px}
  .stats{gap:6px}
  .stats>div{padding:8px 3px}
  .stats strong{font-size:18px}
  .stats small{font-size:10px}
}
@media(max-width:360px){
  .screen{padding-left:0;padding-right:0}
  .number-card{min-height:60px;font-size:25px}
  .expression{font-size:23px}
  .number-pad button,.operator-pad button,.edit-pad button{min-height:45px}
  .stats.timed-layout{gap:4px}
  .stats>div{border-radius:12px}
}