/* ══════════════════════════════════════════════════════
   CodeLab — v3 · 高对比 · 清晰阅读
   ══════════════════════════════════════════════════════ */

:root {
  --bg: #0f0f14;
  --bg2: #16161e;
  --bg3: #1c1c28;
  --card: #1b1b26;
  --card2: #222230;
  --card3: #2a2a3a;
  --border: rgba(255,255,255,.08);
  --border2: rgba(255,255,255,.14);
  --primary: #8b5cf6;
  --primary-d: #7c3aed;
  --accent: #60a5fa;
  --success: #4ade80;
  --warning: #facc15;
  --error: #fb7185;
  --text: #e8e8f0;
  --text2: #c4c4d8;
  --text3: #9494ae;
  --text4: #6b6b82;
  --radius: 10px;
  --radius-sm: 6px;
  --font: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"PingFang SC","Microsoft YaHei",sans-serif;
  --mono: "SF Mono","Fira Code","JetBrains Mono","Consolas",monospace;
}

*{margin:0;padding:0;box-sizing:border-box}
html{font-size:14px}
body{
  font-family:var(--font);
  background:var(--bg);
  color:var(--text);
  min-height:100vh;overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
}
.app-container{max-width:880px;margin:0 auto;min-height:100vh;position:relative}

::selection{background:rgba(139,92,246,.25)}

::-webkit-scrollbar{width:5px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--text4);border-radius:4px}

.loading-spinner,.play-loading{text-align:center;padding:3rem;color:var(--text3);font-size:.9rem}
.spin{
  display:inline-block;width:18px;height:18px;
  border:2px solid var(--text4);border-top-color:var(--accent);
  border-radius:50%;animation:s .6s linear infinite;
  vertical-align:middle;margin-right:8px;
}
@keyframes s{to{transform:rotate(360deg)}}
.empty-state{text-align:center;padding:3rem;color:var(--text3);font-size:.9rem}

/* ── Toast ── */
.toast{
  position:fixed;bottom:28px;left:50%;transform:translateX(-50%);
  background:var(--card2);border:1px solid var(--border2);
  border-radius:var(--radius);padding:12px 24px;z-index:999;
  display:none;font-size:.85rem;
  box-shadow:0 8px 32px rgba(0,0,0,.5);
}
.toast.show{display:block;animation:ti .25s}
@keyframes ti{from{opacity:0;transform:translateX(-50%) translateY(12px)}to{opacity:1;transform:translateX(-50%) translateY(0)}}

/* ═══ HEADER ═══ */
.header{
  position:sticky;top:0;z-index:100;
  background:rgba(15,15,20,.95);backdrop-filter:blur(16px);
  border-bottom:1px solid var(--border);
}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:0 24px;height:54px}
.header-left{display:flex;align-items:center;gap:10px}
.header-back{
  background:none;border:none;color:var(--accent);cursor:pointer;
  padding:6px;border-radius:var(--radius-sm);transition:all .2s;display:flex;
}
.header-back:hover{background:rgba(96,165,250,.1)}
.header-logo{width:30px;height:30px;background:linear-gradient(135deg,var(--primary),var(--accent));border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:.9rem;flex-shrink:0}
.header-title{font-size:1rem;font-weight:700;color:var(--text)}
.header-right{display:flex;align-items:center;gap:12px}
.user-badge{display:flex;align-items:center;gap:10px;font-size:.85rem}
.user-badge-name{color:var(--text2)}
.btn-text{background:none;border:none;color:var(--text3);cursor:pointer;font-size:.8rem;padding:6px 12px;border-radius:var(--radius-sm);transition:all .2s}
.btn-text:hover{color:var(--accent);background:rgba(96,165,250,.08)}

/* ═══ LOGIN ═══ */
#pageLogin{
  display:flex;align-items:center;justify-content:center;
  min-height:100vh;padding:2rem;
  background:radial-gradient(ellipse at 30% 20%,rgba(139,92,246,.06) 0%,transparent 60%),radial-gradient(ellipse at 70% 80%,rgba(96,165,250,.04) 0%,transparent 60%),var(--bg);
}
.login-box{width:100%;max-width:380px;text-align:center}
.login-icon{font-size:3rem;margin-bottom:.5rem}
.login-title{font-size:1.8rem;font-weight:800;margin-bottom:.2rem;color:var(--text)}
.login-sub{color:var(--text3);font-size:.88rem;margin-bottom:1.5rem}
.field{margin-bottom:.8rem}
.field input{width:100%;padding:.75rem 1rem;background:var(--card);border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:.9rem;outline:none;transition:all .2s}
.field input:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(139,92,246,.15)}
.field input::placeholder{color:var(--text4)}
.login-err{color:var(--error);font-size:.8rem;margin-bottom:.5rem;min-height:1.2em;text-align:left}

/* ═══ BUTTONS ═══ */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;padding:10px 22px;border:none;border-radius:var(--radius-sm);font-size:.85rem;font-weight:600;cursor:pointer;transition:all .2s;text-decoration:none}
.btn:active{transform:scale(.97)}
.btn-primary{background:linear-gradient(135deg,var(--primary),var(--primary-d));color:#fff}
.btn-primary:hover{filter:brightness(1.08)}
.btn-primary:disabled{opacity:.5;cursor:not-allowed}
.btn-secondary{background:var(--card2);color:var(--text);border:1px solid var(--border)}
.btn-secondary:hover{background:var(--card3);border-color:var(--border2)}
.btn-accent{background:linear-gradient(135deg,var(--accent),#3b82f6);color:#fff}
.btn-sm{padding:7px 16px;font-size:.8rem}
.btn-full{width:100%}

/* ═══ PLAY ENTRY ═══ */
.play-entry{display:flex;align-items:center;gap:16px;padding:18px 22px;background:linear-gradient(135deg,rgba(139,92,246,.04),rgba(96,165,250,.02));border:1px solid rgba(139,92,246,.1);border-radius:var(--radius);cursor:pointer;transition:all .25s;margin-bottom:28px}
.play-entry:active{transform:scale(.98)}
.play-entry:hover{border-color:rgba(139,92,246,.2);background:linear-gradient(135deg,rgba(139,92,246,.06),rgba(96,165,250,.03))}
.play-entry-icon{font-size:2rem;width:48px;text-align:center;flex-shrink:0}
.play-entry-body{flex:1}
.play-entry-title{font-weight:700;color:var(--text);font-size:1rem}
.play-entry-desc{font-size:.8rem;color:var(--text3);margin-top:2px}

/* ═══ PAGES ═══ */
.page{display:none;padding:24px}

/* ═══ SECTION TITLE ═══ */
.section-title{display:flex;align-items:baseline;gap:10px;margin-bottom:16px;font-size:1.1rem;font-weight:700;flex-wrap:wrap;color:var(--text)}
.section-sub{font-weight:400;font-size:.8rem;color:var(--text3)}

/* ═══ LANGUAGE CARDS ═══ */
.lang-cards{display:grid;grid-template-columns:1fr 1fr;gap:10px}
@media(max-width:550px){.lang-cards{grid-template-columns:1fr}}
.lang-card{display:flex;align-items:center;gap:16px;padding:14px 18px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius);cursor:pointer;transition:all .2s}
.lang-card:active{transform:scale(.98)}
.lang-card:hover{background:var(--card2);border-color:var(--border2);transform:translateY(-2px)}
.lang-card-icon{width:48px;height:48px;border-radius:12px;display:flex;align-items:center;justify-content:center;font-size:1.5rem;flex-shrink:0}
.lang-card-body{flex:1;min-width:0}
.lang-card-name{font-weight:600;color:var(--text);font-size:.92rem}
.lang-card-meta{font-size:.78rem;color:var(--text3);margin-top:2px}
.lang-card-arrow{color:var(--text4);flex-shrink:0;font-size:1.1rem}

/* ═══ FULL PLAYGROUND ═══ */
.play-full{display:flex;flex-direction:column;gap:14px}
.play-full-langs{display:flex;gap:4px;flex-wrap:wrap;background:var(--bg2);border-radius:var(--radius-sm);padding:4px}
.play-full-lang{padding:8px 14px;background:none;border:none;color:var(--text3);font-size:.8rem;border-radius:6px;cursor:pointer;transition:all .2s;white-space:nowrap;font-family:var(--font)}
.play-full-lang.active{background:var(--primary);color:#fff}
.play-full-lang:not(.active):hover{background:rgba(255,255,255,.04);color:var(--text2)}
.play-full-textarea{width:100%;min-height:260px;background:#08080c;color:#e0e0ec;border:1px solid var(--border);border-radius:var(--radius-sm);padding:16px;font-family:var(--mono);font-size:.88rem;line-height:1.7;resize:vertical;outline:none;tab-size:4;transition:border .2s}
.play-full-textarea:focus{border-color:var(--primary)}
.play-full-textarea::placeholder{color:var(--text4)}
.play-full-bar{position:sticky;bottom:0;background:var(--bg);padding:12px 0;z-index:10}
.play-full-actions{display:flex;gap:8px;flex-wrap:wrap}
.play-full-actions .btn{padding:9px 20px;font-size:.85rem}
.pf-empty{text-align:center;padding:3rem;color:var(--text3);font-size:.85rem}
.play-full-preview{margin-top:10px;border:1px solid var(--border);border-radius:var(--radius);overflow:hidden}
.pf-preview-bar{padding:8px 16px;background:var(--card);font-size:.8rem;color:var(--text3);border-bottom:1px solid var(--border)}
.pf-iframe{width:100%;height:350px;border:none;background:#fff;display:block}
.play-history{margin-top:14px}
.play-history-summary{padding:10px 16px;font-size:.8rem;color:var(--text3);cursor:pointer;border-radius:var(--radius-sm);background:var(--card);list-style:none;user-select:none;transition:all .2s}
.play-history-summary::-webkit-details-marker{display:none}
.play-history-summary:hover{background:var(--card2)}
.play-history-list{max-height:260px;overflow-y:auto}
.ph-item{display:flex;align-items:center;gap:10px;padding:8px 14px;font-size:.78rem;color:var(--text2);cursor:pointer;border-radius:var(--radius-sm);transition:all .15s;margin-top:4px}
.ph-item:hover{background:var(--card2)}
.ph-item .ph-lang{font-size:.72rem;color:var(--text3);background:var(--bg2);padding:2px 8px;border-radius:4px}
.ph-item .ph-time{color:var(--text3);margin-left:auto;font-size:.7rem;white-space:nowrap}
.ph-item .ph-preview{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;flex:1}
.ph-clear{text-align:center;padding:8px;font-size:.72rem;color:var(--text3);cursor:pointer;transition:color .2s}
.ph-clear:hover{color:var(--error)}

/* ═══ LESSONS LIST ═══ */
.lessons-header-info{display:flex;align-items:center;gap:18px;margin-bottom:12px}
.lessons-header-icon{font-size:2.8rem}
.lessons-header-text h2{font-size:1.3rem;font-weight:700;color:var(--text)}
.lessons-header-text p{font-size:.82rem;color:var(--text3)}
.lang-intro{font-size:.84rem;color:var(--text3);line-height:1.8;padding:16px 18px;background:var(--card);border-radius:var(--radius-sm);border-left:3px solid var(--primary);margin-bottom:16px}
.lang-progress{display:flex;align-items:center;gap:12px;margin-bottom:12px}
.lang-progress-bar{flex:1;height:6px;background:var(--bg2);border-radius:100px;overflow:hidden}
.lang-progress-fill{height:100%;background:linear-gradient(90deg,var(--primary),var(--accent));border-radius:100px;transition:width .6s ease}
.lang-progress-text{font-size:.74rem;color:var(--text3);white-space:nowrap;font-family:monospace}
.lesson-search{margin-bottom:12px}
.lesson-search input{width:100%;padding:9px 14px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:.85rem;outline:none;transition:all .2s}
.lesson-search input:focus{border-color:var(--primary)}
.lesson-search input::placeholder{color:var(--text4)}
.lesson-cards{display:flex;flex-direction:column;gap:8px}
.lesson-card{display:flex;align-items:center;gap:16px;padding:14px 18px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius-sm);cursor:pointer;transition:all .2s}
.lesson-card:active{transform:scale(.98)}
.lesson-card:hover{background:var(--card2);border-color:var(--border2)}
.lesson-card.done{border-color:rgba(74,222,128,.08)}
.lesson-card-num{font-size:.76rem;color:var(--text3);font-weight:700;width:24px;text-align:center;flex-shrink:0;font-family:monospace}
.lesson-card-body{flex:1;min-width:0}
.lesson-card-title{font-weight:600;color:var(--text);font-size:.9rem}
.lesson-card-meta{display:flex;gap:10px;font-size:.74rem;color:var(--text3);margin-top:2px;flex-wrap:wrap}
.lesson-card-summary{font-size:.8rem;color:var(--text2);margin-top:4px;line-height:1.5}
.lesson-card-badge{font-size:.72rem;color:var(--success);background:rgba(74,222,128,.06);padding:2px 10px;border-radius:6px;font-weight:600;white-space:nowrap}
.lesson-card-arrow{color:var(--text4);flex-shrink:0;font-size:1.1rem}

/* ═══ DIFFICULTY ═══ */
.diff-入门,.diff-beginner{color:var(--success);background:rgba(74,222,128,.06);padding:2px 10px;border-radius:6px;font-size:.72rem;font-weight:500}
.diff-进阶,.diff-intermediate{color:var(--warning);background:rgba(250,204,21,.06);padding:2px 10px;border-radius:6px;font-size:.72rem;font-weight:500}
.diff-高级,.diff-advanced{color:var(--error);background:rgba(251,113,133,.06);padding:2px 10px;border-radius:6px;font-size:.72rem;font-weight:500}

/* ═══ MODAL ═══ */
.modal-overlay{position:fixed;top:0;left:0;width:100%;height:100%;background:rgba(0,0,0,.7);z-index:9999;display:flex;align-items:center;justify-content:center;padding:1rem;animation:mf .2s}
@keyframes mf{from{opacity:0}to{opacity:1}}
.modal-box{background:var(--card2);border:1px solid var(--border);border-radius:var(--radius);max-width:600px;width:100%;max-height:80vh;display:flex;flex-direction:column;box-shadow:0 20px 60px rgba(0,0,0,.5)}
.modal-header{display:flex;align-items:center;justify-content:space-between;padding:14px 20px;border-bottom:1px solid var(--border);font-weight:600;font-size:.9rem}
.modal-close{background:none;border:none;color:var(--text3);font-size:1.2rem;cursor:pointer;padding:4px 10px;border-radius:var(--radius-sm);transition:all .2s}
.modal-close:hover{color:var(--error);background:rgba(251,113,133,.08)}
.modal-code{flex:1;overflow:auto;padding:16px 20px;font-family:var(--mono);font-size:.82rem;line-height:1.7;white-space:pre-wrap;color:var(--text2);background:var(--bg2);margin:0}
.modal-actions{display:flex;gap:8px;padding:12px 20px;border-top:1px solid var(--border);justify-content:flex-end}

/* ═══ LESSON DETAIL ═══ */
.ld-header{margin-bottom:20px;padding-bottom:16px;border-bottom:1px solid var(--border)}
.ld-header-top{display:flex;gap:10px;margin-bottom:8px;align-items:center}
.ld-done-badge{color:var(--success);font-size:.76rem;font-weight:600;background:rgba(74,222,128,.06);padding:2px 10px;border-radius:6px}
.ld-title{font-size:1.3rem;font-weight:700;color:var(--text);margin-bottom:4px}
.ld-summary{font-size:.86rem;color:var(--text3)}
.ld-content{line-height:1.9;font-size:.9rem;color:var(--text2)}
.ld-content h2{font-size:1.15rem;font-weight:700;margin:1.6rem 0 .6rem;color:var(--text);padding-bottom:8px;border-bottom:1px solid var(--border)}
.ld-content h3{font-size:.95rem;font-weight:600;margin:1.2rem 0 .5rem;color:var(--text)}
.ld-content p{margin:.6rem 0}
.ld-content strong{color:var(--text)}
.ld-content code{background:rgba(139,92,246,.06);color:var(--accent);padding:2px 8px;border-radius:4px;font-size:.85em}
.ld-content pre{background:var(--bg2);padding:16px;border-radius:var(--radius-sm);overflow-x:auto;margin:12px 0;border:1px solid var(--border);font-size:.82rem;line-height:1.6}
.ld-content pre code{background:none;padding:0;color:#d4d4e4}
.ld-content table{width:100%;border-collapse:collapse;margin:12px 0;font-size:.84rem}
.ld-content th,.ld-content td{border:1px solid var(--border);padding:8px 12px;text-align:left}
.ld-content th{background:rgba(139,92,246,.04);color:var(--text);font-weight:600}
.ld-content blockquote{border-left:3px solid var(--primary);padding:10px 16px;margin:12px 0;background:rgba(139,92,246,.02);border-radius:0 8px 8px 0}
.ld-content ul,.ld-content ol{padding-left:1.5rem;margin:8px 0}
.ld-content li{margin:4px 0}
.ld-content hr{border:none;border-top:1px solid var(--border);margin:1.4rem 0}
.ld-example{margin:20px 0;padding:16px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius)}
.ld-example-code{margin-top:10px;background:var(--bg2);padding:16px;border-radius:var(--radius-sm);font-size:.82rem;overflow-x:auto;border:1px solid var(--border)}
.ld-exercises{margin-top:28px;padding-top:20px;border-top:1px solid var(--border)}
.ld-ex-title{font-size:1.05rem;font-weight:700;color:var(--text);margin-bottom:16px}
.ex-tabs{display:flex;gap:4px;margin-bottom:16px;background:var(--bg2);border-radius:var(--radius-sm);padding:4px;flex-wrap:wrap}
.ex-tab{padding:8px 16px;background:none;border:none;color:var(--text3);font-size:.8rem;border-radius:6px;cursor:pointer;transition:all .2s;white-space:nowrap}
.ex-tab.active{background:var(--primary);color:#fff}
.ex-tab:not(.active):hover{background:rgba(255,255,255,.04);color:var(--text2)}
.ex-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:18px;margin-bottom:16px}
.ex-card-title{font-weight:600;color:var(--text);margin-bottom:4px;font-size:.92rem}
.ex-card-desc{font-size:.82rem;color:var(--text2);margin-bottom:6px}
.ex-card-req{font-size:.8rem;color:var(--text3);margin-bottom:12px;padding:12px;background:var(--bg2);border-radius:var(--radius-sm)}
.ex-textarea{width:100%;min-height:150px;background:#08080c;color:#e0e0ec;border:1px solid var(--border);border-radius:var(--radius-sm);padding:14px;font-family:var(--mono);font-size:.85rem;line-height:1.6;resize:vertical;outline:none;tab-size:4;transition:border .2s}
.ex-textarea:focus{border-color:var(--primary)}
.ex-actions{display:flex;gap:8px;margin-bottom:10px}
.ex-actions .btn{flex:1}
.ex-ref{margin-top:10px;background:var(--bg2);padding:12px;border-radius:var(--radius-sm);font-size:.8rem;overflow-x:auto;border:1px solid var(--border)}
.ex-result{margin-top:12px}
.ld-complete{margin-top:20px}
.done-banner{text-align:center;padding:1.4rem;background:rgba(74,222,128,.04);border:1px solid rgba(74,222,128,.08);border-radius:var(--radius);color:var(--success);font-weight:600;font-size:.9rem}

/* ═══ RESULTS ═══ */
.result-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:10px}
.result-card.success{border-color:rgba(74,222,128,.1)}
.result-card.error{border-color:rgba(251,113,133,.1)}
.result-card.review{border-color:rgba(139,92,246,.1)}
.result-title{font-size:.82rem;font-weight:600;color:var(--text3);margin-bottom:8px}
.result-output{background:var(--bg2);padding:14px;border-radius:var(--radius-sm);font-size:.8rem;line-height:1.6;white-space:pre-wrap;overflow-x:auto;max-height:300px;overflow-y:auto;font-family:monospace}
.result-meta{font-size:.74rem;color:var(--text3);margin-top:8px}
.review-score{font-size:2rem;font-weight:700;text-align:center;margin:.5rem 0}
.review-score.high{color:var(--success)}
.review-score.mid{color:var(--warning)}
.review-score.low{color:var(--error)}
.review-score-label{font-size:.8rem;font-weight:400}
.review-summary{text-align:center;font-size:.86rem;color:var(--text2);margin-bottom:10px}
.review-section{margin-top:14px}
.review-section-title{font-weight:600;font-size:.84rem;color:var(--text);margin-bottom:6px}
.review-section ul{padding-left:1.2rem}
.review-section li{margin:4px 0;font-size:.82rem}
.review-text{background:var(--bg2);padding:14px;border-radius:var(--radius-sm);font-size:.8rem;line-height:1.6;white-space:pre-wrap;margin-top:6px}

/* ═══ RESPONSIVE ═══ */
@media(max-width:768px){
  .app-container{max-width:100%}
  .page{padding:16px}
  .header-inner{padding:0 16px}
  .play-entry{padding:14px 16px}
  .play-full-textarea{min-height:180px}
  .pf-iframe{height:240px}
}
@media(max-width:480px){
  html{font-size:13px}
  .page{padding:12px}
  .header-inner{height:48px;padding:0 12px}
  .play-entry{gap:10px;padding:12px}
  .play-entry-icon{font-size:1.6rem;width:40px}
  .play-full-lang{padding:6px 10px;font-size:.76rem}
  .play-full-textarea{min-height:140px;padding:12px}
  .play-full-actions .btn{padding:7px 14px}
  .ex-textarea{min-height:100px}
  .login-box{max-width:100%}
  .lesson-card{padding:10px 12px}
}