.java-course{--bg:#fdfcf9;--bg-soft:#f5f2ec;--surface:#fff;--ink:#264653;--ink-soft:#4a6a78;--muted:#8aa0ab;--primary:#e76f51;--primary-soft:#f4a28c;--teal:#2a9d8f;--teal-soft:#7fcbc0;--sand:#e9c46a;--line:#e8e2d6;--code-bg:#1e1e2e;--code-fg:#cdd6f4;--radius:14px;--shadow:0 4px 24px #26465314;--shadow-lg:0 12px 40px #26465324;--font:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",Roboto,Helvetica,Arial,sans-serif;--mono:"SF Mono","Fira Code","JetBrains Mono",Menlo,Consolas,monospace}.java-course *{box-sizing:border-box;margin:0;padding:0}.java-course{scroll-behavior:smooth;font-family:var(--font);background:var(--bg);color:var(--ink);-webkit-font-smoothing:antialiased;height:100vh;scroll-padding-top:80px;font-size:15px;line-height:1.7;overflow-y:auto}.java-course .app{grid-template-columns:280px 1fr;max-width:1180px;min-height:calc(100vh - 53px);margin:0 auto;display:grid}.java-course header.top{z-index:40;backdrop-filter:saturate(180%)blur(10px);border-bottom:1px solid var(--line);background:#fdfcf9d9;position:sticky;top:0}.java-course .top-in{align-items:center;gap:16px;max-width:1180px;margin:0 auto;padding:10px 22px;display:flex}.java-course .brand{letter-spacing:.3px;align-items:center;gap:10px;font-weight:800;display:flex}.java-course .brand-logo{background:linear-gradient(135deg,var(--primary),var(--sand));color:#fff;border-radius:8px;flex-shrink:0;place-items:center;width:30px;height:30px;font-size:15px;font-weight:800;display:grid;box-shadow:0 4px 10px #e76f5159}.java-course .brand small{color:var(--muted);font-size:12px;font-weight:600}.java-course .header-progress{flex:1;align-items:center;gap:10px;display:flex}.java-course .header-track{background:var(--bg-soft);border-radius:99px;flex:1;height:8px;overflow:hidden}.java-course .header-fill{background:linear-gradient(90deg,var(--primary),var(--sand));border-radius:99px;width:0;height:100%;transition:width .4s}.java-course .header-pct{color:var(--muted);text-align:right;min-width:44px;font-size:12px;font-weight:700}.java-course .menu-btn{border:1px solid var(--line);cursor:pointer;background:0 0;border-radius:9px;padding:7px 10px;font-size:18px;line-height:1;display:none}.java-course aside.side{border-right:1px solid var(--line);background:var(--surface);scrollbar-width:none;height:calc(100vh - 53px);padding:22px 14px;position:sticky;top:53px;overflow-y:auto}.java-course aside.side::-webkit-scrollbar{display:none}.java-course aside.side:after{content:"";background:linear-gradient(to bottom,transparent,var(--surface));pointer-events:none;height:28px;margin:0 -14px -22px;display:block;position:sticky;bottom:0;left:0;right:0}.java-course .side h3{text-transform:uppercase;letter-spacing:1.5px;color:var(--muted);margin:14px 10px 8px;font-size:11px}.java-course .nav-item{cursor:pointer;color:var(--ink-soft);border-radius:9px;align-items:center;gap:10px;padding:9px 12px;font-size:13.5px;font-weight:500;transition:all .18s;display:flex;position:relative}.java-course .nav-item:hover{background:var(--bg-soft);color:var(--ink)}.java-course .nav-item.active{color:var(--primary);background:linear-gradient(90deg,#e76f511f,#0000);font-weight:600}.java-course .nav-item.active:before{content:"";background:var(--primary);border-radius:99px;width:3px;height:18px;position:absolute;top:50%;left:0;transform:translateY(-50%)}.java-course .nav-num{background:var(--bg-soft);width:24px;height:24px;color:var(--muted);border-radius:7px;flex-shrink:0;justify-content:center;align-items:center;font-size:11px;font-weight:700;transition:all .18s;display:flex}.java-course .nav-item.active .nav-num{background:var(--primary);color:#fff}.java-course .nav-item.done .nav-num{background:var(--teal);color:#fff}.java-course .nav-item.done .nav-num:after{content:"✓";font-size:13px}.java-course .nav-item.done .nav-num span{display:none}.java-course .nav-title{text-overflow:ellipsis;white-space:nowrap;flex:1;overflow:hidden}.java-course .side-foot{margin-top:18px;padding:0 10px}.java-course .reset-btn{border:1px solid var(--line);width:100%;color:var(--muted);cursor:pointer;background:0 0;border-radius:9px;padding:8px;font-size:12px;font-weight:600}.java-course .reset-btn:hover{border-color:var(--primary);color:var(--primary)}.java-course .side-foot .motto{text-align:center;color:var(--muted);margin-top:10px;font-size:11px}.java-course main.content{min-width:0}.java-course .topbar{z-index:50;backdrop-filter:blur(12px);border-bottom:1px solid var(--line);background:#fdfcf9e0;justify-content:space-between;align-items:center;padding:14px 40px;display:flex;position:sticky;top:53px}.java-course .topbar-left{align-items:center;gap:14px;display:flex}.java-course .day-badge{color:var(--primary);background:#e76f511a;border-radius:99px;padding:4px 12px;font-size:12px;font-weight:700}.java-course .topbar-title{color:var(--ink);font-size:15px;font-weight:600}.java-course .topbar-actions{gap:8px;display:flex}.java-course .btn{cursor:pointer;font-family:var(--font);border:none;border-radius:9px;align-items:center;gap:6px;padding:8px 16px;font-size:13px;font-weight:600;transition:all .18s;display:inline-flex}.java-course .btn-ghost{color:var(--ink-soft);border:1px solid var(--line);background:0 0}.java-course .btn-ghost:hover{background:var(--bg-soft)}.java-course .btn-primary{background:var(--primary);color:#fff;box-shadow:0 2px 8px #e76f514d}.java-course .btn-primary:hover{background:#d65a3c;transform:translateY(-1px)}.java-course .btn:disabled{opacity:.4;cursor:not-allowed;transform:none!important}.java-course .content{max-width:840px;margin:0 auto;padding:36px 40px 80px}.java-course .hero{text-align:center;padding:50px 0 40px}.java-course .hero-badge{color:var(--teal);background:#2a9d8f1a;border-radius:99px;margin-bottom:22px;padding:6px 16px;font-size:13px;font-weight:600;display:inline-block}.java-course .hero h2{color:var(--ink);letter-spacing:-.02em;font-size:34px;font-weight:800;line-height:1.25}.java-course .hero h2 em{color:var(--primary);font-style:normal;position:relative}.java-course .hero h2 em:after{content:"";z-index:-1;background:#e9c46a73;border-radius:99px;width:100%;height:8px;position:absolute;bottom:2px;left:0}.java-course .hero p{color:var(--ink-soft);max-width:560px;margin:18px auto 0;font-size:16px}.java-course .hero-stats{flex-wrap:wrap;justify-content:center;gap:36px;margin-top:34px;display:flex}.java-course .hero-stat{text-align:center}.java-course .hero-stat .num{color:var(--primary);font-size:28px;font-weight:800}.java-course .hero-stat .lbl{color:var(--muted);margin-top:2px;font-size:12px}.java-course .feature-grid{grid-template-columns:repeat(3,1fr);gap:18px;margin-top:44px;display:grid}.java-course .feature-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);cursor:pointer;padding:24px;transition:all .25s}.java-course .feature-card:hover{box-shadow:var(--shadow);border-color:var(--primary-soft);transform:translateY(-3px)}.java-course .feature-icon{border-radius:11px;justify-content:center;align-items:center;width:44px;height:44px;margin-bottom:14px;font-size:22px;display:flex}.java-course .feature-card h3{margin-bottom:6px;font-size:15px;font-weight:700}.java-course .feature-card p{color:var(--muted);font-size:13px;line-height:1.55}.java-course .start-cta{text-align:center;margin-top:46px}.java-course .btn-big{border-radius:12px;padding:14px 36px;font-size:16px}.java-course .lesson{animation:.4s fadein;display:none}.java-course .lesson.show{display:block}@keyframes fadein{0%{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}.java-course .lesson-tag{color:var(--teal);text-transform:uppercase;letter-spacing:.08em;font-size:12px;font-weight:700}.java-course .lesson h2{letter-spacing:-.01em;margin:8px 0 6px;font-size:28px;font-weight:800}.java-course .lesson-sub{color:var(--ink-soft);margin-bottom:30px;font-size:15px}.java-course h3.sub{color:var(--ink);align-items:center;gap:9px;margin:32px 0 12px;font-size:19px;font-weight:700;display:flex}.java-course h3.sub .dot{background:var(--primary);border-radius:50%;flex-shrink:0;width:8px;height:8px}.java-course p.lead{color:var(--ink-soft);margin-bottom:14px}.java-course strong{color:var(--ink)}.java-course em.kw{color:var(--primary);font-style:normal;font-weight:600}.java-course .code-block{background:var(--code-bg);border:1px solid #313244;border-radius:12px;margin:16px 0;overflow:hidden;box-shadow:0 4px 20px #1e1e2e2e}.java-course .code-head{background:#181825;border-bottom:1px solid #313244;justify-content:space-between;align-items:center;padding:9px 16px;display:flex}.java-course .code-head .dots{gap:6px;display:flex}.java-course .code-head .dots span{border-radius:50%;width:11px;height:11px}.java-course .code-head .dots span:first-child{background:#f38ba8}.java-course .code-head .dots span:nth-child(2){background:#f9e2af}.java-course .code-head .dots span:nth-child(3){background:#a6e3a1}.java-course .code-head .fname{font-family:var(--mono);color:#7f849c;font-size:12px}.java-course .code-run{color:#a6e3a1;cursor:pointer;font-family:var(--font);background:#a6e3a11f;border:none;border-radius:7px;align-items:center;gap:5px;padding:5px 12px;font-size:12px;font-weight:600;transition:all .15s;display:inline-flex}.java-course .code-run:hover{background:#a6e3a138}.java-course pre.code{background:var(--code-bg);color:var(--code-fg);font-family:var(--mono);border-radius:0;margin:0;padding:16px 18px;font-size:13.5px;line-height:1.65;position:relative;overflow-x:auto}.java-course pre.code code{font-family:var(--mono);background:0 0}.java-course pre.code .line{display:block}.java-course pre.code .copy{color:#cfcbe6;cursor:pointer;opacity:0;background:#ffffff14;border:1px solid #ffffff1f;border-radius:7px;padding:3px 9px;font-size:11px;transition:all .2s;position:absolute;top:8px;right:8px}.java-course pre.code:hover .copy{opacity:1}.java-course pre.code .copy:hover{background:#ffffff29}.java-course .output-box{background:#11111b;border:1px solid #313244;border-top:none;border-radius:0 0 12px 12px;max-height:0;margin-top:0;padding:0;transition:max-height .35s,padding .35s;overflow:hidden}.java-course .output-box.show{max-height:300px;padding:14px 18px;overflow-y:auto}.java-course .output-label{color:#6c7086;text-transform:uppercase;letter-spacing:.06em;margin-bottom:6px;font-size:11px;font-weight:600}.java-course .output-content{font-family:var(--mono);color:#a6e3a1;white-space:pre-wrap;font-size:13px;line-height:1.6}.java-course .callout{border-radius:12px;align-items:flex-start;gap:13px;margin:18px 0;padding:16px 18px;font-size:14px;line-height:1.65;display:flex}.java-course .callout-icon{flex-shrink:0;margin-top:1px;font-size:18px}.java-course .callout-tip{border-left:3px solid var(--teal);background:#2a9d8f14}.java-course .callout-tip .callout-icon{color:var(--teal)}.java-course .callout-warn{border-left:3px solid var(--primary);background:#e76f5114}.java-course .callout-warn .callout-icon{color:var(--primary)}.java-course .callout-info{border-left:3px solid var(--sand);background:#e9c46a1a}.java-course .callout-info .callout-icon{color:#b8860b}.java-course .callout b{color:var(--ink)}.java-course .table-wrap{border:1px solid var(--line);border-radius:12px;margin:16px 0;overflow-x:auto}.java-course table{border-collapse:collapse;background:var(--surface);width:100%;font-size:13.5px}.java-course th{background:var(--bg-soft);text-align:left;color:var(--ink);border-bottom:2px solid var(--line);white-space:nowrap;padding:11px 14px;font-weight:700}.java-course td{border-bottom:1px solid var(--line);color:var(--ink-soft);padding:10px 14px}.java-course tr:last-child td{border-bottom:none}.java-course td code{font-family:var(--mono);background:var(--bg-soft);color:var(--primary);border-radius:4px;padding:2px 6px;font-size:12.5px}.java-course .quiz{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);margin:24px 0;padding:24px}.java-course .quiz-head{align-items:center;gap:10px;margin-bottom:16px;display:flex}.java-course .quiz-icon{background:linear-gradient(135deg,var(--sand),var(--primary));color:#fff;border-radius:9px;justify-content:center;align-items:center;width:34px;height:34px;font-size:16px;font-weight:700;display:flex}.java-course .quiz-title{font-size:16px;font-weight:700}.java-course .quiz-q{margin-bottom:14px;font-size:15px;font-weight:600;line-height:1.5}.java-course .quiz-opts{flex-direction:column;gap:9px;display:flex}.java-course .quiz-opt{border:1.5px solid var(--line);cursor:pointer;background:var(--bg);border-radius:10px;align-items:center;gap:11px;padding:12px 16px;font-size:14px;transition:all .18s;display:flex}.java-course .quiz-opt:hover{border-color:var(--primary-soft);background:var(--bg-soft)}.java-course .quiz-opt.selected{border-color:var(--primary);background:#e76f510f}.java-course .quiz-opt.correct{border-color:var(--teal);background:#2a9d8f14}.java-course .quiz-opt.wrong{background:#e639460f;border-color:#e63946}.java-course .quiz-opt .marker{border:2px solid var(--line);width:22px;height:22px;color:var(--muted);border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;font-size:12px;font-weight:700;transition:all .18s;display:flex}.java-course .quiz-opt.selected .marker{border-color:var(--primary);color:var(--primary)}.java-course .quiz-opt.correct .marker{border-color:var(--teal);background:var(--teal);color:#fff}.java-course .quiz-opt.wrong .marker{color:#fff;background:#e63946;border-color:#e63946}.java-course .quiz-feedback{border-radius:10px;margin-top:14px;padding:13px 16px;font-size:13.5px;line-height:1.6;display:none}.java-course .quiz-feedback.show{animation:.3s fadein;display:block}.java-course .quiz-feedback.ok{color:var(--teal);background:#2a9d8f1a}.java-course .quiz-feedback.no{color:#c1121f;background:#e6394614}.java-course .quiz-feedback b{color:inherit}.java-course .exercise{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);margin:24px 0;padding:24px}.java-course .ex-head{align-items:center;gap:10px;margin-bottom:6px;display:flex}.java-course .ex-icon{background:linear-gradient(135deg,var(--teal),var(--teal-soft));color:#fff;border-radius:9px;justify-content:center;align-items:center;width:34px;height:34px;font-size:16px;font-weight:700;display:flex}.java-course .ex-title{font-size:16px;font-weight:700}.java-course .ex-desc{color:var(--ink-soft);margin-bottom:16px;font-size:14px}.java-course .fill-code{background:var(--code-bg);font-family:var(--mono);color:var(--code-fg);white-space:pre;border-radius:10px;margin-bottom:14px;padding:16px 18px;font-size:13.5px;line-height:1.8;position:relative;overflow-x:auto}.java-course .fill-code code{font-family:var(--mono);background:0 0}.java-course .fill-input{color:#f9e2af;min-width:90px;font-family:var(--mono);background:#f9e2af26;border:1px dashed #f9e2af;border-radius:5px;outline:none;width:auto;padding:1px 8px;font-size:13px;transition:all .2s;display:inline-block}.java-course .fill-input:focus{background:#f9e2af40;border-style:solid}.java-course .fill-input.correct{color:#a6e3a1;background:#a6e3a133;border-color:#a6e3a1}.java-course .fill-input.wrong{color:#f38ba8;background:#f38ba826;border-color:#f38ba8}.java-course .ex-check{background:var(--teal);color:#fff;cursor:pointer;font-family:var(--font);border:none;border-radius:9px;padding:8px 20px;font-size:13px;font-weight:600;transition:all .18s}.java-course .ex-check:hover{background:#24877c}.java-course .ex-result{margin-top:12px;font-size:13.5px;font-weight:600;display:none}.java-course .ex-result.show{animation:.3s fadein;display:block}.java-course .ex-result.ok{color:var(--teal)}.java-course .ex-result.no{color:#e63946}.java-course .complete-card{text-align:center;border:1.5px dashed var(--primary-soft);border-radius:var(--radius);background:linear-gradient(135deg,#e76f510f,#2a9d8f0f);margin-top:30px;padding:40px 30px}.java-course .complete-card .emoji{margin-bottom:10px;font-size:42px}.java-course .complete-card h3{margin-bottom:8px;font-size:20px;font-weight:800}.java-course .complete-card p{color:var(--ink-soft);margin-bottom:18px;font-size:14px}.java-course .complete-card .btn{font-size:14px}.java-course .lesson-nav{justify-content:space-between;gap:12px;margin-top:36px;display:flex}@media (width<=860px){.java-course .app{grid-template-columns:1fr}.java-course aside.side{z-index:30;width:280px;height:calc(100vh - 53px);transition:all .25s;position:fixed;top:53px;left:0;transform:translate(-100%);box-shadow:0 8px 30px #2646532e}.java-course aside.side.open{transform:none}.java-course .menu-btn{display:block}.java-course main.content{padding:0}.java-course .content{padding:24px 20px 60px}.java-course .topbar{padding:14px 20px}.java-course .feature-grid{grid-template-columns:1fr}.java-course .hero h2{font-size:26px}}