/* ============================================================
   CTL 刷题 · 学生端  —  炫酷童趣风（5~7年级）
   配色：糖果紫蓝渐变 + 霓虹青 + 活力黄
   字体：系统清晰黑体（PingFang SC / Microsoft YaHei），保证小朋友易读
   注意：本文件类名与 app.js 完全保持一致，仅做视觉重做
   ============================================================ */

:root{
  --bg:#eef1ff;
  --bg2:#fef0f6;
  --card:#ffffff;
  --text:#2b2350;
  --muted:#8a85b3;
  --primary:#7b5cff;
  --primary-dark:#5a3fd6;
  --primary-2:#22d3ff;
  --accent:#ffcf3f;
  --correct:#23c879;
  --correct-bg:#e6fbf0;
  --wrong:#ff5d8f;
  --wrong-bg:#ffe9f1;
  --border:#ece9ff;
  --tag-mc:#7b5cff;
  --tag-tf:#ff9f43;
  --shadow:0 12px 30px rgba(123,92,255,0.16);
  --shadow-pop:0 10px 24px rgba(34,211,255,0.22);
  --radius:22px;
}
*{box-sizing:border-box;}
html,body{margin:0;padding:0;}
body{
  background:
    radial-gradient(1200px 600px at 12% -8%, #ffe6f3 0%, transparent 55%),
    radial-gradient(1000px 600px at 100% 0%, #dff3ff 0%, transparent 50%),
    linear-gradient(160deg, var(--bg) 0%, var(--bg2) 100%);
  background-attachment:fixed;
  color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
  min-height:100vh;
  -webkit-tap-highlight-color:transparent;
  overflow-x:hidden;
}

/* 漂浮装饰球 */
.bg-orbs{position:fixed;inset:0;z-index:0;pointer-events:none;overflow:hidden;}
.bg-orbs span{position:absolute;border-radius:50%;filter:blur(2px);opacity:.55;animation:floaty 9s ease-in-out infinite;}
.bg-orbs span:nth-child(1){width:120px;height:120px;left:6%;top:18%;background:radial-gradient(circle at 30% 30%,#ffd6e8,#ff8fc0);animation-delay:0s;}
.bg-orbs span:nth-child(2){width:80px;height:80px;right:10%;top:12%;background:radial-gradient(circle at 30% 30%,#cfe7ff,#7bb8ff);animation-delay:1.4s;}
.bg-orbs span:nth-child(3){width:60px;height:60px;left:18%;bottom:14%;background:radial-gradient(circle at 30% 30%,#fff0c2,#ffcf3f);animation-delay:2.6s;}
.bg-orbs span:nth-child(4){width:100px;height:100px;right:8%;bottom:16%;background:radial-gradient(circle at 30% 30%,#e3d6ff,#b79bff);animation-delay:3.4s;}
@keyframes floaty{0%,100%{transform:translateY(0) rotate(0)}50%{transform:translateY(-26px) rotate(12deg)}}

#app{position:relative;z-index:1;max-width:640px;margin:0 auto;padding:16px 16px 48px;}

header.topbar{
  display:flex;align-items:center;justify-content:space-between;
  padding:8px 4px 16px;gap:8px;
}
header.topbar h1{
  font-size:22px;margin:0;font-weight:800;
  background:linear-gradient(90deg,var(--primary),var(--primary-2));
  -webkit-background-clip:text;background-clip:text;color:transparent;
  letter-spacing:.5px;
}
header.topbar .icon-btn{
  background:var(--card);border:2px solid var(--border);border-radius:16px;
  padding:9px 14px;font-size:14px;color:var(--text);cursor:pointer;
  display:flex;align-items:center;gap:4px;box-shadow:var(--shadow-pop);
  transition:transform .12s ease;
}
header.topbar .icon-btn:active{transform:scale(.94);}
.icon-btn-group{display:flex;gap:8px;}

.user-bar{
  display:flex;align-items:center;justify-content:space-between;gap:8px;
  background:var(--card);border-radius:18px;box-shadow:var(--shadow);
  padding:12px 16px;margin-bottom:14px;font-size:14px;border:2px solid var(--border);
}
.user-bar .who{display:flex;align-items:center;gap:10px;font-weight:700;}
.user-bar .who .avatar{
  width:36px;height:36px;border-radius:50%;
  background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;
  display:flex;align-items:center;justify-content:center;font-size:16px;font-weight:800;
  box-shadow:0 4px 10px rgba(123,92,255,.4);
}
.user-bar .logout{
  background:var(--bg);border:2px solid var(--border);color:var(--muted);
  border-radius:12px;padding:7px 12px;font-size:12px;cursor:pointer;font-family:inherit;
}

.stats-strip{
  display:flex;background:var(--card);border-radius:18px;box-shadow:var(--shadow);
  padding:14px 6px;margin-bottom:16px;border:2px solid var(--border);
}
.stats-strip .stat{flex:1;text-align:center;position:relative;}
.stats-strip .stat + .stat::before{content:"";position:absolute;left:0;top:18%;height:64%;width:2px;background:var(--border);border-radius:2px;}
.stats-strip .stat .num{font-size:20px;font-weight:800;background:linear-gradient(90deg,var(--primary),var(--primary-2));-webkit-background-clip:text;background-clip:text;color:transparent;}
.stats-strip .stat .lbl{font-size:11px;color:var(--muted);margin-top:3px;}

.progress-wrap{margin-bottom:12px;}
.progress-track{height:12px;background:var(--bg);border-radius:10px;overflow:hidden;border:2px solid var(--border);}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--primary),var(--primary-2));border-radius:10px;transition:width .35s ease;box-shadow:0 0 12px rgba(34,211,255,.5);}
.progress-text{font-size:12px;color:var(--muted);margin-top:6px;text-align:right;}

.quiz-card{
  background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  padding:24px 22px;position:relative;overflow:hidden;
  border:2px solid var(--border);transition:background-color .5s ease;
}
.quiz-card::before{
  content:"";position:absolute;right:-40px;top:-40px;width:140px;height:140px;border-radius:50%;
  background:radial-gradient(circle,rgba(34,211,255,.18),transparent 70%);
}
.q-tag{
  display:inline-block;font-size:12px;font-weight:800;color:#fff;
  padding:4px 12px;border-radius:999px;margin-bottom:12px;letter-spacing:.5px;
  box-shadow:0 4px 10px rgba(123,92,255,.35);
}
.q-tag.mc{background:linear-gradient(135deg,#8a6bff,#6a4bff);}
.q-tag.tf{background:linear-gradient(135deg,#ffb15c,#ff8a3c);}
.q-text{font-size:17px;line-height:1.6;font-weight:700;margin:0 0 14px;white-space:pre-wrap;}
pre.codebox{
  background:#1c1f3a;color:#e7ecff;border-radius:14px;padding:14px 16px;
  font-size:13px;line-height:1.55;overflow-x:auto;margin:0 0 16px;
  font-family:"SFMono-Regular",Consolas,"Courier New",monospace;
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.06);
}
.options{display:flex;flex-direction:column;gap:12px;}
.opt-btn{
  text-align:left;background:var(--bg);border:2.5px solid var(--border);
  border-radius:16px;padding:14px 16px;font-size:15px;color:var(--text);
  cursor:pointer;transition:transform .12s ease, border-color .15s ease, background-color .15s ease, box-shadow .15s ease;
  display:flex;gap:12px;align-items:center;width:100%;font-family:inherit;position:relative;
}
.opt-btn .opt-letter{
  flex:0 0 auto;width:30px;height:30px;border-radius:50%;
  background:linear-gradient(135deg,#f0ecff,#e2dbff);color:var(--primary);border:2px solid var(--border);
  display:flex;align-items:center;justify-content:center;font-size:14px;font-weight:800;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
}
.opt-btn .opt-text{white-space:pre-wrap;flex:1;font-weight:600;}
.opt-btn .opt-text.codey{font-family:Consolas,"Courier New",monospace;font-size:13px;white-space:pre-wrap;}
.opt-btn:not(.disabled):hover{border-color:var(--primary);transform:translateY(-2px);box-shadow:var(--shadow-pop);}
.opt-btn:not(.disabled):active{transform:scale(.98);}
.opt-btn.tf-btn{justify-content:center;text-align:center;font-weight:800;font-size:16px;}
.opt-btn.disabled{cursor:default;}
.opt-btn.selected-wrong{border-color:var(--wrong);background:var(--wrong-bg);}
.opt-btn.selected-wrong .opt-letter{background:var(--wrong);color:#fff;border-color:var(--wrong);}
.opt-btn.reveal-correct{border-color:var(--correct);background:var(--correct-bg);}
.opt-btn.reveal-correct .opt-letter{background:var(--correct);color:#fff;border-color:var(--correct);}
.opt-btn.answer-correct-flash{border-color:var(--correct);background:var(--correct-bg);animation:pop-scale .5s ease;}
.opt-btn.answer-correct-flash .opt-letter{background:var(--correct);color:#fff;border-color:var(--correct);}

@keyframes pop-scale{0%{transform:scale(1);}35%{transform:scale(1.04);}100%{transform:scale(1);}}
@keyframes flash-bg{0%{box-shadow:0 0 0 8px rgba(35,200,121,.35), var(--shadow);}100%{box-shadow:var(--shadow);}}
.quiz-card.flash-correct{animation:flash-bg .8s ease;}

.feedback-banner{
  margin-top:16px;border-radius:14px;padding:13px 15px;font-size:14px;font-weight:800;
  display:flex;align-items:center;gap:8px;
}
.feedback-banner.good{background:var(--correct-bg);color:var(--correct);}
.feedback-banner.bad{background:var(--wrong-bg);color:var(--wrong);}

.explain-box{
  margin-top:12px;background:var(--bg);border:2px solid var(--border);border-radius:14px;
  padding:13px 15px;font-size:13.5px;line-height:1.6;color:var(--text);
}
.explain-box .explain-title{font-weight:800;margin-bottom:6px;color:var(--primary);}
.explain-box .teacher-tip{margin-top:10px;padding-top:10px;border-top:2px dashed var(--border);color:var(--muted);display:flex;gap:6px;align-items:center;}

.checkmark-burst{
  position:absolute;top:16px;right:18px;font-size:32px;
  animation:check-pop .55s ease;
}
@keyframes check-pop{0%{transform:scale(0) rotate(-15deg);opacity:0;}55%{transform:scale(1.25) rotate(6deg);opacity:1;}100%{transform:scale(1) rotate(0deg);opacity:1;}}

.confetti{position:absolute;top:0;left:0;width:100%;height:100%;pointer-events:none;overflow:hidden;}
.confetti span{position:absolute;font-size:18px;top:-10px;animation:confetti-fall 1.1s ease-in forwards;}
@keyframes confetti-fall{0%{transform:translateY(-10px) rotate(0deg);opacity:1;}100%{transform:translateY(220px) rotate(340deg);opacity:0;}}

.next-row{margin-top:18px;display:flex;justify-content:flex-end;}
.next-btn{
  background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;border:none;border-radius:16px;
  padding:13px 26px;font-size:15px;font-weight:800;cursor:pointer;box-shadow:0 8px 18px rgba(123,92,255,.4);
  font-family:inherit;letter-spacing:.5px;
}
.next-btn:active{transform:scale(.97);}

.summary-card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:30px 24px;text-align:center;border:2px solid var(--border);}
.summary-card .big-score{font-size:48px;font-weight:800;background:linear-gradient(90deg,var(--primary),var(--primary-2));-webkit-background-clip:text;background-clip:text;color:transparent;margin:10px 0;}
.summary-card .sub{color:var(--muted);font-size:14px;margin-bottom:18px;}
.summary-actions{display:flex;gap:10px;justify-content:center;margin-top:10px;flex-wrap:wrap;}
.summary-actions button{border-radius:16px;padding:12px 20px;font-size:14px;font-weight:800;cursor:pointer;border:none;font-family:inherit;}
.summary-actions .primary-action{background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;box-shadow:0 8px 18px rgba(123,92,255,.4);}
.summary-actions .secondary-action{background:var(--bg);color:var(--text);border:2px solid var(--border);}

.overlay{position:fixed;inset:0;background:rgba(43,35,80,0.5);backdrop-filter:blur(3px);display:none;align-items:flex-end;justify-content:center;z-index:50;}
.overlay.show{display:flex;}
.sheet{
  background:var(--card);width:100%;max-width:640px;border-radius:24px 24px 0 0;
  max-height:85vh;overflow-y:auto;padding:20px 20px 28px;border:2px solid var(--border);border-bottom:none;
  animation:sheet-up .25s ease;
}
@keyframes sheet-up{from{transform:translateY(24px);opacity:0;}to{transform:translateY(0);opacity:1;}}
.sheet-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px;}
.sheet-head h2{font-size:18px;margin:0;color:var(--primary);}
.sheet-head .close-btn{background:var(--bg);border:2px solid var(--border);border-radius:12px;padding:7px 12px;cursor:pointer;font-size:13px;color:var(--text);font-family:inherit;}

.history-summary{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-bottom:16px;}
.history-summary .box{background:var(--bg);border-radius:14px;padding:12px 6px;text-align:center;border:2px solid var(--border);}
.history-summary .box .num{font-size:17px;font-weight:800;color:var(--primary);}
.history-summary .box .lbl{font-size:10.5px;color:var(--muted);margin-top:3px;}

.history-item{border:2px solid var(--border);border-radius:14px;padding:11px 14px;margin-bottom:8px;font-size:13px;background:var(--card);}
.history-item .row1{display:flex;justify-content:space-between;align-items:center;gap:8px;}
.history-item .q-snip{flex:1;color:var(--text);font-weight:700;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;}
.history-item .badge{flex:0 0 auto;font-size:11px;font-weight:800;border-radius:8px;padding:2px 8px;}
.history-item .badge.ok{background:var(--correct-bg);color:var(--correct);}
.history-item .badge.no{background:var(--wrong-bg);color:var(--wrong);}
.history-item .meta{color:var(--muted);font-size:11px;margin-top:4px;}
.empty-hint{color:var(--muted);font-size:13px;text-align:center;padding:24px 0;}

.badge-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;}
.badge-card{border-radius:16px;padding:16px 12px;text-align:center;border:2px solid var(--border);background:var(--card);box-shadow:var(--shadow-pop);}
.badge-card .badge-icon{
  width:60px;height:60px;border-radius:50%;margin:0 auto 8px;display:flex;align-items:center;
  justify-content:center;font-size:28px;background:linear-gradient(135deg,#f0ecff,#e2dbff);
}
.badge-card.locked{opacity:0.5;}
.badge-card.locked .badge-icon{background:var(--bg);filter:grayscale(1);}
.badge-card .badge-name{font-size:13px;font-weight:800;margin-bottom:4px;}
.badge-card .badge-desc{font-size:11px;color:var(--muted);line-height:1.4;}
.badge-card .tier-tag{display:inline-block;margin-top:6px;font-size:10px;font-weight:800;border-radius:8px;padding:2px 8px;color:#fff;}
.tier-bronze .badge-icon{background:linear-gradient(135deg,#d99a5b,#a8622f);}
.tier-bronze .tier-tag{background:#a8622f;}
.tier-silver .badge-icon{background:linear-gradient(135deg,#d7dbe2,#9aa1ac);}
.tier-silver .tier-tag{background:#8b93a0;}
.tier-gold .badge-icon{background:linear-gradient(135deg,#ffe08a,#f5b700);}
.tier-gold .tier-tag{background:#e0a500;}
.tier-diamond .badge-icon{background:linear-gradient(135deg,#a0e9ff,#7b93ff);}
.tier-diamond .tier-tag{background:#6a7ff0;}

.toast{
  position:fixed;top:18px;left:50%;transform:translateX(-50%) translateY(-20px);
  background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;padding:12px 18px;border-radius:14px;font-size:13.5px;font-weight:800;
  box-shadow:var(--shadow);z-index:80;opacity:0;transition:all .3s ease;display:flex;gap:8px;align-items:center;
  max-width:90vw;text-align:center;font-family:inherit;
}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0);}

/* ================= 登录页 ================= */
.login-mask{
  position:fixed;inset:0;display:flex;align-items:center;justify-content:center;
  padding:20px;z-index:100;overflow-y:auto;
  background:
    radial-gradient(900px 500px at 15% -5%, #ffe6f3 0%, transparent 55%),
    radial-gradient(800px 500px at 100% 5%, #dff3ff 0%, transparent 50%),
    linear-gradient(160deg, var(--bg) 0%, var(--bg2) 100%);
}
.login-card{
  width:100%;max-width:410px;background:var(--card);border-radius:26px;box-shadow:var(--shadow);
  padding:34px 28px 28px;border:2px solid var(--border);position:relative;overflow:hidden;
}
.login-card::before{
  content:"";position:absolute;left:-30px;top:-30px;width:120px;height:120px;border-radius:50%;
  background:radial-gradient(circle,rgba(123,92,255,.18),transparent 70%);
}
.login-card .logo{
  font-size:54px;text-align:center;margin-bottom:4px;
  filter:drop-shadow(0 6px 10px rgba(123,92,255,.35));
  animation:bob 3s ease-in-out infinite;
}
@keyframes bob{0%,100%{transform:translateY(0)}50%{transform:translateY(-7px)}}
.login-card h1{font-size:25px;text-align:center;margin:0 0 4px;font-weight:800;
  background:linear-gradient(90deg,var(--primary),var(--primary-2));-webkit-background-clip:text;background-clip:text;color:transparent;}
.login-card .sub{text-align:center;color:var(--muted);font-size:13px;margin-bottom:24px;font-weight:500;}
.field{margin-bottom:16px;}
.field label{display:block;font-size:13px;font-weight:800;margin-bottom:7px;color:var(--text);}
.field input,.field select,.field textarea{
  width:100%;border:2px solid var(--border);background:var(--bg);color:var(--text);
  border-radius:14px;padding:13px 15px;font-size:15px;outline:none;font-family:inherit;
  transition:border-color .15s ease, box-shadow .15s ease;
}
.field input:focus,.field textarea:focus{border-color:var(--primary);box-shadow:0 0 0 4px rgba(123,92,255,.15);}
.login-btn{
  width:100%;background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;border:none;border-radius:16px;
  padding:15px;font-size:17px;font-weight:800;cursor:pointer;margin-top:8px;font-family:inherit;letter-spacing:1px;
  box-shadow:0 10px 22px rgba(123,92,255,.42);transition:transform .12s ease, box-shadow .15s ease;
}
.login-btn:active{transform:scale(.98);box-shadow:0 6px 14px rgba(123,92,255,.4);}
.login-btn:disabled{opacity:0.6;cursor:default;}
.login-err{
  color:var(--wrong);background:var(--wrong-bg);border:2px solid #ffd0e0;border-radius:12px;padding:10px 13px;
  font-size:13px;margin-bottom:14px;display:none;font-weight:700;
}
.login-err.show{display:block;}
.login-tip{margin-top:18px;text-align:center;font-size:12px;color:var(--muted);line-height:1.7;font-weight:500;}
.role-switch{display:flex;gap:10px;margin-bottom:18px;}
.role-switch button{
  flex:1;background:var(--bg);border:2px solid var(--border);color:var(--text);
  border-radius:14px;padding:11px;font-size:14px;font-weight:800;cursor:pointer;font-family:inherit;transition:all .15s ease;
}
.role-switch button.active{border-color:var(--primary);color:var(--primary);background:#fff;box-shadow:0 6px 14px rgba(123,92,255,.2);}

@media (max-width:420px){
  #app{padding:12px 12px 30px;}
  header.topbar h1{font-size:19px;}
  .stats-strip .stat .num{font-size:17px;}
  .quiz-card{padding:20px 16px;}
}