/* ════════════════════════════════════════
   CodeLab — Styles
   ════════════════════════════════════════ */
:root {
  --bg: #0c0c18;
  --bg2: #111122;
  --card: #181830;
  --card2: #1e1e3a;
  --border: rgba(255,255,255,.06);
  --primary: #6c5ce7;
  --primary-d: #5a4bd1;
  --accent: #00d2ff;
  --success: #00e676;
  --warning: #ffc107;
  --error: #ff5252;
  --text: #ddd;
  --text2: #9898b0;
  --text3: #6868a0;
  --radius: 10px;
  --radius2: 6px;
}
*{margin:0;padding:0;box-sizing:border-box}
html{font-size:15px}
body{
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"PingFang SC","Microsoft YaHei",sans-serif;
  background:var(--bg);color:var(--text);min-height:100vh;overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
}
.app-container{max-width:520px;margin:0 auto;min-height:100vh;position:relative}

/* ─── Scrollbar ── */
::-webkit-scrollbar{width:4px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:2px}

/* ─── Loading ── */
.loading-spinner,.play-loading{text-align:center;padding:2rem;color:var(--text3);font-size:.85rem}
.spin{display:inline-block;width:16px;height:16px;border:2px solid var(--text3);border-top-color:var(--accent);border-radius:50%;animation:s 0.7s linear infinite;vertical-align:middle;margin-right:6px}
@keyframes s{to{transform:rotate(360deg)}}
.empty-state{text-align:center;padding:2rem;color:var(--text3);font-size:.85rem}

/* ─── Toast ── */
.toast{position:fixed;bottom:20px;left:50%;transform:translateX(-50%);background:var(--card);border:1px solid var(--border);border-radius:8px;padding:10px 18px;z-index:999;display:none;max-width:90%;font-size:.85rem;box-shadow:0 8px 30px rgba(0,0,0,.4)}
.toast.show{display:block;animation:ti .3s}
@keyframes ti{from{opacity:0;transform:translateX(-50%) translateY(20px)}to{opacity:1;transform:translateX(-50%) translateY(0)}}

/* ═══ HEADER ═══ */
.header{
  position:sticky;top:0;z-index:100;background:rgba(12,12,24,.92);backdrop-filter:blur(16px);
  border-bottom:1px solid var(--border)
}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:0 14px;height:50px}
.header-left{display:flex;align-items:center;gap:6px}
.header-back{
  background:none;border:none;color:var(--accent);cursor:pointer;padding:4px;display:flex;align-items:center;
  border-radius:8px;transition:background .2s
}
.header-back:hover{background:rgba(0,210,255,.08)}
.header-logo{width:28px;height:28px;background:linear-gradient(135deg,var(--primary),var(--accent));border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:.85rem;flex-shrink:0}
.header-title{font-size:1rem;font-weight:700;color:#fff}
.header-right{display:flex;align-items:center;gap:8px}
.user-badge{display:flex;align-items:center;gap:8px;font-size:.8rem}
.user-badge-name{color:var(--text2)}
.btn-text{background:none;border:none;color:var(--text3);cursor:pointer;font-size:.8rem;padding:4px 8px;border-radius:6px;transition:all .2s}
.btn-text:hover{color:var(--accent);background:rgba(0,210,255,.06)}

/* ═══ LOGIN PAGE ═══ */
.page-login{display:flex;align-items:center;justify-content:center;min-height:100vh;padding:2rem;background:linear-gradient(135deg,#0c0c18 0%,#12122e 50%,#0c0c18 100%)}
.login-box{width:100%;max-width:360px;text-align:center}
.login-icon{font-size:3rem;margin-bottom:.5rem}
.login-title{font-size:1.6rem;font-weight:800;margin-bottom:.2rem}
.login-sub{color:var(--text3);font-size:.85rem;margin-bottom:1.5rem}
.login-tabs{display:flex;gap:0;margin-bottom:1.2rem;background:var(--card);border-radius:10px;padding:3px}
.login-tab{flex:1;padding:8px;background:none;border:none;color:var(--text3);font-size:.85rem;border-radius:8px;cursor:pointer;transition:all .2s}
.login-tab.active{background:var(--primary);color:#fff}
.login-form{text-align:left}
.field{margin-bottom:.8rem}
.field input{width:100%;padding:.7rem .9rem;background:var(--card);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:.9rem;outline:none;transition:border .2s}
.field input:focus{border-color:var(--accent)}
.login-err{color:var(--error);font-size:.8rem;margin-bottom:.6rem;min-height:1.2em;text-align:left}

/* ═══ PLAYGROUND ENTRY CARD ═══ */
.play-entry{
  display:flex;align-items:center;gap:14px;padding:16px;
  background:linear-gradient(135deg,rgba(108,92,231,.08),rgba(0,210,255,.05));
  border:1px solid rgba(108,92,231,.2);border-radius:var(--radius);
  cursor:pointer;transition:all .25s;margin-bottom:20px
}
.play-entry:active{transform:scale(.98)}
.play-entry:hover{border-color:rgba(108,92,231,.4);background:linear-gradient(135deg,rgba(108,92,231,.12),rgba(0,210,255,.08))}
.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:#fff;font-size:1rem}
.play-entry-desc{font-size:.78rem;color:var(--text3);margin-top:2px}
.play-entry-arrow{color:var(--text3);opacity:.4}

/* ═══ FULL PLAYGROUND PAGE ═══ */
.play-full{display:flex;flex-direction:column;gap:12px}
.play-full-langs{display:flex;gap:4px;background:var(--bg2);border-radius:8px;padding:3px}
.play-full-lang{flex:1;padding:8px 4px;background:none;border:none;color:var(--text3);font-size:.78rem;border-radius:6px;cursor:pointer;transition:all .2s;text-align:center}
.play-full-lang.active{background:var(--primary);color:#fff}
.play-full-editor{flex:1}
.play-full-textarea{width:100%;min-height:200px;background:var(--bg2);color:var(--text);border:1px solid var(--border);border-radius:8px;padding:12px;font-family:"SF Mono","Fira Code","Consolas",monospace;font-size:.82rem;line-height:1.6;resize:vertical;outline:none;tab-size:4}
.play-full-textarea:focus{border-color:var(--accent)}
.play-full-bar{position:sticky;bottom:0;background:var(--bg);padding:8px 0;z-index:10}
.play-full-actions{display:flex;gap:6px;flex-wrap:wrap}
.play-full-actions .btn{flex:1;min-width:0;padding:8px 6px;font-size:.78rem;white-space:nowrap}
.play-full-output{}
.pf-empty{text-align:center;padding:2rem;color:var(--text3);font-size:.82rem}

@media(min-width:480px){
  .play-full-textarea{min-height:280px}
  .play-full-lang{padding:8px 12px}
}

/* ═══ BUTTONS ═══ */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;padding:9px 18px;border:none;border-radius:8px;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{opacity:.9}
.btn-primary:disabled{opacity:.5;cursor:not-allowed}
.btn-secondary{background:var(--card2);color:var(--text);border:1px solid var(--border)}
.btn-accent{background:linear-gradient(135deg,var(--accent),#0099cc);color:var(--bg)}
.btn-sm{padding:6px 14px;font-size:.8rem}
.btn-full{width:100%}
.btn-text{background:none;border:none;color:var(--text3);cursor:pointer;padding:4px 8px;border-radius:6px;font-size:.8rem;transition:color .2s}
.btn-text:hover{color:var(--accent)}

/* ═══ PAGES ═══ */
.page{display:none;padding:16px}

/* ═══ SECTION TITLE ═══ */
.section-title{display:flex;align-items:baseline;gap:8px;margin-bottom:12px;font-size:1.05rem;font-weight:700;flex-wrap:wrap}
.section-sub{font-weight:400;font-size:.78rem;color:var(--text3)}

/* ═══ PLAYGROUND ═══ */
.playground{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:20px}
.play-langs{display:flex;gap:4px;margin-bottom:10px;background:var(--bg2);border-radius:8px;padding:3px}
.play-lang{flex:1;padding:7px;background:none;border:none;color:var(--text3);font-size:.8rem;border-radius:6px;cursor:pointer;transition:all .2s}
.play-lang.active{background:var(--primary);color:#fff}
.play-editor{margin-bottom:10px}
.play-textarea{width:100%;min-height:140px;background:var(--bg2);color:var(--text);border:1px solid var(--border);border-radius:8px;padding:12px;font-family:"SF Mono","Fira Code","Consolas",monospace;font-size:.82rem;line-height:1.6;resize:vertical;outline:none;tab-size:4}
.play-textarea:focus{border-color:var(--accent)}
.play-actions{display:flex;gap:8px;margin-bottom:10px}
.play-actions .btn{flex:1}
.play-output{}
.play-loading{text-align:center;padding:1rem;color:var(--text3);font-size:.85rem}

/* ═══ LANGUAGE CARDS ═══ */
.lang-cards{display:flex;flex-direction:column;gap:10px}
.lang-card{
  display:flex;align-items:center;gap:14px;padding:14px 16px;
  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-icon{width:44px;height:44px;border-radius:12px;display:flex;align-items:center;justify-content:center;font-size:1.4rem;flex-shrink:0}
.lang-card-body{flex:1}
.lang-card-name{font-weight:600;color:#fff}
.lang-card-meta{font-size:.78rem;color:var(--text3);margin-top:2px}
.lang-card-arrow{color:var(--text3);opacity:.5}

/* ═══ LESSONS PAGE ═══ */
.lessons-header-info{display:flex;align-items:center;gap:14px;margin-bottom:8px}
.lessons-header-icon{font-size:2.5rem}
.lessons-header-text h2{font-size:1.2rem;font-weight:700}
.lessons-header-text p{font-size:.8rem;color:var(--text3)}
.lang-intro{font-size:.82rem;color:var(--text3);line-height:1.6;padding:12px;background:var(--card);border-radius:var(--radius);border-left:3px solid var(--primary);margin-bottom:12px}
.lesson-cards{display:flex;flex-direction:column;gap:6px}
.lesson-card{
  display:flex;align-items:center;gap:12px;padding:12px 14px;
  background:var(--card);border:1px solid var(--border);border-radius:var(--radius);
  cursor:pointer;transition:all .2s;position:relative
}
.lesson-card:active{transform:scale(.98)}
.lesson-card.done{border-color:rgba(0,230,118,.15)}
.lesson-card-num{font-size:.75rem;color:var(--text3);font-weight:700;width:24px;text-align:center;flex-shrink:0;font-family:monospace}
.lesson-card-body{flex:1}
.lesson-card-title{font-weight:600;color:#fff;font-size:.9rem}
.lesson-card-meta{display:flex;gap:8px;font-size:.72rem;color:var(--text3);margin-top:2px}
.lesson-card-summary{font-size:.78rem;color:var(--text3);margin-top:4px;line-height:1.4}
.lesson-card-badge{font-size:.7rem;color:var(--success);background:rgba(0,230,118,.1);padding:3px 8px;border-radius:6px;font-weight:600;white-space:nowrap}
.lesson-card-arrow{color:var(--text3);opacity:.4}

/* ═══ DIFFICULTY BADGES ═══ */
.diff-入门,.diff-beginner{color:var(--success);background:rgba(0,230,118,.12);padding:1px 7px;border-radius:6px;font-size:.72rem;font-weight:500}
.diff-进阶,.diff-intermediate{color:var(--warning);background:rgba(255,193,7,.12);padding:1px 7px;border-radius:6px;font-size:.72rem;font-weight:500}
.diff-高级,.diff-advanced{color:var(--error);background:rgba(255,82,82,.12);padding:1px 7px;border-radius:6px;font-size:.72rem;font-weight:500}

/* ═══ LESSON DETAIL ═══ */
.ld-header{margin-bottom:16px;padding-bottom:12px;border-bottom:1px solid var(--border)}
.ld-header-top{display:flex;gap:8px;margin-bottom:6px}
.ld-done-badge{color:var(--success);font-size:.75rem;font-weight:600;background:rgba(0,230,118,.1);padding:2px 10px;border-radius:6px}
.ld-title{font-size:1.2rem;font-weight:700;margin-bottom:4px}
.ld-summary{font-size:.85rem;color:var(--text3)}

/* ── Lesson Content (HTML) ── */
.ld-content{line-height:1.8;font-size:.88rem}
.ld-content h2{font-size:1.05rem;font-weight:700;margin:1.2rem 0 .5rem;color:#fff;padding-bottom:4px;border-bottom:1px solid var(--border)}
.ld-content h3{font-size:.95rem;font-weight:600;margin:.8rem 0 .4rem;color:#eee}
.ld-content p{margin:.4rem 0;color:var(--text2)}
.ld-content strong{color:#fff}
.ld-content code{background:rgba(108,92,231,.1);color:var(--accent);padding:1px 5px;border-radius:4px;font-size:.85em}
.ld-content pre{background:var(--bg2);padding:12px;border-radius:8px;overflow-x:auto;margin:8px 0;border:1px solid var(--border);font-size:.8rem;line-height:1.5}
.ld-content pre code{background:none;padding:0;color:var(--text)}
.ld-content table{width:100%;border-collapse:collapse;margin:8px 0;font-size:.82rem}
.ld-content th,.ld-content td{border:1px solid var(--border);padding:5px 8px;text-align:left}
.ld-content th{background:rgba(108,92,231,.08);color:#fff;font-weight:600}
.ld-content blockquote{border-left:3px solid var(--primary);padding:6px 12px;margin:8px 0;background:rgba(108,92,231,.04);border-radius:0 6px 6px 0;color:var(--text2)}
.ld-content ul,.ld-content ol{padding-left:1.3rem;margin:4px 0}
.ld-content li{color:var(--text2);margin:2px 0}
.ld-content hr{border:none;border-top:1px solid var(--border);margin:1rem 0}
.ld-content blockquote strong{color:#fff}

/* ── Example ── */
.ld-example{margin:16px 0;padding:12px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius)}
.ld-example-code{margin-top:10px;background:var(--bg2);padding:12px;border-radius:8px;font-size:.8rem;overflow-x:auto;border:1px solid var(--border)}

/* ── Exercises ── */
.ld-exercises{margin-top:20px;padding-top:16px;border-top:1px solid var(--border)}
.ld-ex-title{font-size:1rem;font-weight:700;margin-bottom:12px}
.ex-tabs{display:flex;gap:4px;margin-bottom:12px;background:var(--bg2);border-radius:8px;padding:3px}
.ex-tab{flex:1;padding:7px;background:none;border:none;color:var(--text3);font-size:.78rem;border-radius:6px;cursor:pointer;transition:all .2s}
.ex-tab.active{background:var(--primary);color:#fff}
.ex-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:14px;margin-bottom:12px}
.ex-card-title{font-weight:600;color:#fff;margin-bottom:4px}
.ex-card-desc{font-size:.82rem;color:var(--text2);margin-bottom:4px}
.ex-card-req{font-size:.8rem;color:var(--text3);margin-bottom:10px;padding:8px;background:var(--bg2);border-radius:6px}
.ex-editor{margin-bottom:8px}
.ex-textarea{width:100%;min-height:120px;background:var(--bg2);color:var(--text);border:1px solid var(--border);border-radius:8px;padding:10px;font-family:"SF Mono","Fira Code","Consolas",monospace;font-size:.82rem;line-height:1.5;resize:vertical;outline:none;tab-size:4}
.ex-textarea:focus{border-color:var(--accent)}
.ex-actions{display:flex;gap:8px;margin-bottom:8px}
.ex-actions .btn{flex:1}
.ex-ref{margin-top:6px;background:var(--bg2);padding:10px;border-radius:8px;font-size:.78rem;overflow-x:auto;border:1px solid var(--border)}
.ex-result{margin-top:8px}
.ld-complete{margin-top:16px}
.done-banner{text-align:center;padding:1rem;background:rgba(0,230,118,.08);border:1px solid rgba(0,230,118,.15);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:12px;margin-bottom:8px}
.result-card.success{border-color:rgba(0,230,118,.2)}
.result-card.error{border-color:rgba(255,82,82,.2)}
.result-card.review{border-color:rgba(108,92,231,.2);background:linear-gradient(135deg,rgba(108,92,231,.05),rgba(0,210,255,.03))}
.result-title{font-size:.8rem;font-weight:600;color:var(--text3);margin-bottom:6px}
.result-output{background:var(--bg2);padding:10px;border-radius:6px;font-size:.78rem;line-height:1.5;white-space:pre-wrap;overflow-x:auto;max-height:200px;overflow-y:auto;font-family:monospace}
.result-meta{font-size:.72rem;color:var(--text3);margin-top:6px}
.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:.85rem;color:var(--text2);margin-bottom:10px}
.review-section{margin-top:10px}
.review-section-title{font-weight:600;font-size:.82rem;margin-bottom:4px}
.review-section ul{padding-left:1.2rem}
.review-section li{margin:3px 0;font-size:.8rem}
.review-text{background:var(--bg2);padding:10px;border-radius:6px;font-size:.78rem;line-height:1.5;white-space:pre-wrap;margin-top:4px}

/* ═══ Responsive ═══ */
@media(min-width:768px){
  .app-container{max-width:700px}
  .play-textarea{min-height:180px}
}