.java-course{--bg:#FDFCF9;--bg-soft:#F5F2EC;--surface:#FFFFFF;--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 rgba(38,70,83,.08);--shadow-lg:0 12px 40px rgba(38,70,83,.14);--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);line-height:1.7;font-size:15px;-webkit-font-smoothing:antialiased;height:100vh;overflow-y:auto;scroll-padding-top:80px}.java-course .app{display:grid;grid-template-columns:280px 1fr;max-width:1180px;margin:0 auto;min-height:calc(100vh - 53px)}.java-course header.top{position:sticky;top:0;z-index:40;background:#fdfcf9d9;backdrop-filter:saturate(180%) blur(10px);border-bottom:1px solid var(--line)}.java-course .top-in{display:flex;align-items:center;gap:16px;padding:10px 22px;max-width:1180px;margin:0 auto}.java-course .brand{display:flex;align-items:center;gap:10px;font-weight:800;letter-spacing:.3px}.java-course .brand-logo{width:30px;height:30px;border-radius:8px;background:linear-gradient(135deg,var(--primary),var(--sand));display:grid;place-items:center;color:#fff;font-weight:800;font-size:15px;flex-shrink:0;box-shadow:0 4px 10px #e76f5159}.java-course .brand small{font-weight:600;color:var(--muted);font-size:12px}.java-course .header-progress{flex:1;display:flex;align-items:center;gap:10px}.java-course .header-track{flex:1;height:8px;background:var(--bg-soft);border-radius:99px;overflow:hidden}.java-course .header-fill{height:100%;width:0;background:linear-gradient(90deg,var(--primary),var(--sand));border-radius:99px;transition:width .4s ease}.java-course .header-pct{font-size:12px;color:var(--muted);font-weight:700;min-width:44px;text-align:right}.java-course .menu-btn{display:none;background:none;border:1px solid var(--line);border-radius:9px;padding:7px 10px;cursor:pointer;font-size:18px;line-height:1}.java-course aside.side{border-right:1px solid var(--line);padding:22px 14px;position:sticky;top:53px;height:calc(100vh - 53px);overflow-y:auto;background:var(--surface);scrollbar-width:none}.java-course aside.side::-webkit-scrollbar{display:none}.java-course aside.side:after{content:"";position:sticky;bottom:0;left:0;right:0;display:block;height:28px;margin:0 -14px -22px;background:linear-gradient(to bottom,transparent,var(--surface));pointer-events:none}.java-course .side h3{font-size:11px;text-transform:uppercase;letter-spacing:1.5px;color:var(--muted);margin:14px 10px 8px}.java-course .nav-item{display:flex;align-items:center;gap:10px;padding:9px 12px;border-radius:9px;cursor:pointer;font-size:13.5px;color:var(--ink-soft);font-weight:500;transition:all .18s ease;position:relative}.java-course .nav-item:hover{background:var(--bg-soft);color:var(--ink)}.java-course .nav-item.active{background:linear-gradient(90deg,rgba(231,111,81,.12),transparent);color:var(--primary);font-weight:600}.java-course .nav-item.active:before{content:"";position:absolute;left:0;top:50%;transform:translateY(-50%);width:3px;height:18px;background:var(--primary);border-radius:99px}.java-course .nav-num{width:24px;height:24px;border-radius:7px;flex-shrink:0;display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:700;background:var(--bg-soft);color:var(--muted);transition:all .18s}.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{flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.java-course .side-foot{margin-top:18px;padding:0 10px}.java-course .reset-btn{width:100%;background:none;border:1px solid var(--line);color:var(--muted);padding:8px;border-radius:9px;cursor:pointer;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;font-size:11px;color:var(--muted);margin-top:10px}.java-course main.content{min-width:0}.java-course .topbar{position:sticky;top:53px;z-index:50;background:#fdfcf9e0;backdrop-filter:blur(12px);border-bottom:1px solid var(--line);padding:14px 40px;display:flex;align-items:center;justify-content:space-between}.java-course .topbar-left{display:flex;align-items:center;gap:14px}.java-course .day-badge{font-size:12px;font-weight:700;color:var(--primary);background:#e76f511a;padding:4px 12px;border-radius:99px}.java-course .topbar-title{font-size:15px;font-weight:600;color:var(--ink)}.java-course .topbar-actions{display:flex;gap:8px}.java-course .btn{border:none;cursor:pointer;font-family:var(--font);font-weight:600;padding:8px 16px;border-radius:9px;font-size:13px;transition:all .18s;display:inline-flex;align-items:center;gap:6px}.java-course .btn-ghost{background:transparent;color:var(--ink-soft);border:1px solid var(--line)}.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{display:inline-block;font-size:13px;color:var(--teal);background:#2a9d8f1a;padding:6px 16px;border-radius:99px;font-weight:600;margin-bottom:22px}.java-course .hero h2{font-size:34px;font-weight:800;line-height:1.25;color:var(--ink);letter-spacing:-.02em}.java-course .hero h2 em{font-style:normal;color:var(--primary);position:relative}.java-course .hero h2 em:after{content:"";position:absolute;left:0;bottom:2px;width:100%;height:8px;background:#e9c46a73;border-radius:99px;z-index:-1}.java-course .hero p{font-size:16px;color:var(--ink-soft);max-width:560px;margin:18px auto 0}.java-course .hero-stats{display:flex;gap:36px;justify-content:center;margin-top:34px;flex-wrap:wrap}.java-course .hero-stat{text-align:center}.java-course .hero-stat .num{font-size:28px;font-weight:800;color:var(--primary)}.java-course .hero-stat .lbl{font-size:12px;color:var(--muted);margin-top:2px}.java-course .feature-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin-top:44px}.java-course .feature-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:24px;transition:all .25s;cursor:pointer}.java-course .feature-card:hover{box-shadow:var(--shadow);transform:translateY(-3px);border-color:var(--primary-soft)}.java-course .feature-icon{width:44px;height:44px;border-radius:11px;display:flex;align-items:center;justify-content:center;font-size:22px;margin-bottom:14px}.java-course .feature-card h3{font-size:15px;font-weight:700;margin-bottom:6px}.java-course .feature-card p{font-size:13px;color:var(--muted);line-height:1.55}.java-course .start-cta{text-align:center;margin-top:46px}.java-course .btn-big{font-size:16px;padding:14px 36px;border-radius:12px}.java-course .lesson{display:none;animation:fadein .4s ease}.java-course .lesson.show{display:block}@keyframes fadein{0%{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}.java-course .lesson-tag{font-size:12px;font-weight:700;color:var(--teal);text-transform:uppercase;letter-spacing:.08em}.java-course .lesson h2{font-size:28px;font-weight:800;margin:8px 0 6px;letter-spacing:-.01em}.java-course .lesson-sub{color:var(--ink-soft);font-size:15px;margin-bottom:30px}.java-course h3.sub{font-size:19px;font-weight:700;margin:32px 0 12px;color:var(--ink);display:flex;align-items:center;gap:9px}.java-course h3.sub .dot{width:8px;height:8px;border-radius:50%;background:var(--primary);flex-shrink:0}.java-course p.lead{margin-bottom:14px;color:var(--ink-soft)}.java-course strong{color:var(--ink)}.java-course em.kw{font-style:normal;color:var(--primary);font-weight:600}.java-course .code-block{background:var(--code-bg);border-radius:12px;overflow:hidden;margin:16px 0;box-shadow:0 4px 20px #1e1e2e2e;border:1px solid #313244}.java-course .code-head{display:flex;align-items:center;justify-content:space-between;padding:9px 16px;background:#181825;border-bottom:1px solid #313244}.java-course .code-head .dots{display:flex;gap:6px}.java-course .code-head .dots span{width:11px;height:11px;border-radius:50%}.java-course .code-head .dots span:nth-child(1){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);font-size:12px;color:#7f849c}.java-course .code-run{background:#a6e3a11f;color:#a6e3a1;border:none;cursor:pointer;font-family:var(--font);font-size:12px;font-weight:600;padding:5px 12px;border-radius:7px;display:inline-flex;align-items:center;gap:5px;transition:all .15s}.java-course .code-run:hover{background:#a6e3a138}.java-course pre.code{background:var(--code-bg);color:var(--code-fg);padding:16px 18px;border-radius:0;overflow-x:auto;margin:0;font-family:var(--mono);font-size:13.5px;line-height:1.65;position:relative}.java-course pre.code code{font-family:var(--mono);background:none}.java-course pre.code .line{display:block}.java-course pre.code .copy{position:absolute;top:8px;right:8px;background:#ffffff14;border:1px solid rgba(255,255,255,.12);color:#cfcbe6;font-size:11px;padding:3px 9px;border-radius:7px;cursor:pointer;opacity:0;transition:.2s}.java-course pre.code:hover .copy{opacity:1}.java-course pre.code .copy:hover{background:#ffffff29}.java-course .output-box{margin-top:0;border-radius:0 0 12px 12px;background:#11111b;border:1px solid #313244;border-top:none;padding:0;max-height:0;overflow:hidden;transition:max-height .35s ease,padding .35s ease}.java-course .output-box.show{max-height:300px;padding:14px 18px;overflow-y:auto}.java-course .output-label{font-size:11px;color:#6c7086;font-weight:600;text-transform:uppercase;letter-spacing:.06em;margin-bottom:6px}.java-course .output-content{font-family:var(--mono);font-size:13px;color:#a6e3a1;white-space:pre-wrap;line-height:1.6}.java-course .callout{border-radius:12px;padding:16px 18px;margin:18px 0;display:flex;gap:13px;align-items:flex-start;font-size:14px;line-height:1.65}.java-course .callout-icon{font-size:18px;flex-shrink:0;margin-top:1px}.java-course .callout-tip{background:#2a9d8f14;border-left:3px solid var(--teal)}.java-course .callout-tip .callout-icon{color:var(--teal)}.java-course .callout-warn{background:#e76f5114;border-left:3px solid var(--primary)}.java-course .callout-warn .callout-icon{color:var(--primary)}.java-course .callout-info{background:#e9c46a1a;border-left:3px solid var(--sand)}.java-course .callout-info .callout-icon{color:#b8860b}.java-course .callout b{color:var(--ink)}.java-course .table-wrap{overflow-x:auto;margin:16px 0;border-radius:12px;border:1px solid var(--line)}.java-course table{width:100%;border-collapse:collapse;font-size:13.5px;background:var(--surface)}.java-course th{background:var(--bg-soft);text-align:left;padding:11px 14px;font-weight:700;color:var(--ink);border-bottom:2px solid var(--line);white-space:nowrap}.java-course td{padding:10px 14px;border-bottom:1px solid var(--line);color:var(--ink-soft)}.java-course tr:last-child td{border-bottom:none}.java-course td code{font-family:var(--mono);font-size:12.5px;background:var(--bg-soft);padding:2px 6px;border-radius:4px;color:var(--primary)}.java-course .quiz{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:24px;margin:24px 0;box-shadow:var(--shadow)}.java-course .quiz-head{display:flex;align-items:center;gap:10px;margin-bottom:16px}.java-course .quiz-icon{width:34px;height:34px;border-radius:9px;background:linear-gradient(135deg,var(--sand),var(--primary));display:flex;align-items:center;justify-content:center;color:#fff;font-size:16px;font-weight:700}.java-course .quiz-title{font-size:16px;font-weight:700}.java-course .quiz-q{font-size:15px;font-weight:600;margin-bottom:14px;line-height:1.5}.java-course .quiz-opts{display:flex;flex-direction:column;gap:9px}.java-course .quiz-opt{display:flex;align-items:center;gap:11px;padding:12px 16px;border:1.5px solid var(--line);border-radius:10px;cursor:pointer;font-size:14px;transition:all .18s;background:var(--bg)}.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{border-color:#e63946;background:#e639460f}.java-course .quiz-opt .marker{width:22px;height:22px;border-radius:50%;border:2px solid var(--line);flex-shrink:0;display:flex;align-items:center;justify-content:center;font-size:12px;font-weight:700;color:var(--muted);transition:all .18s}.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{border-color:#e63946;background:#e63946;color:#fff}.java-course .quiz-feedback{margin-top:14px;padding:13px 16px;border-radius:10px;font-size:13.5px;display:none;line-height:1.6}.java-course .quiz-feedback.show{display:block;animation:fadein .3s}.java-course .quiz-feedback.ok{background:#2a9d8f1a;color:var(--teal)}.java-course .quiz-feedback.no{background:#e6394614;color:#c1121f}.java-course .quiz-feedback b{color:inherit}.java-course .exercise{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:24px;margin:24px 0;box-shadow:var(--shadow)}.java-course .ex-head{display:flex;align-items:center;gap:10px;margin-bottom:6px}.java-course .ex-icon{width:34px;height:34px;border-radius:9px;background:linear-gradient(135deg,var(--teal),var(--teal-soft));display:flex;align-items:center;justify-content:center;color:#fff;font-size:16px;font-weight:700}.java-course .ex-title{font-size:16px;font-weight:700}.java-course .ex-desc{font-size:14px;color:var(--ink-soft);margin-bottom:16px}.java-course .fill-code{background:var(--code-bg);border-radius:10px;padding:16px 18px;font-family:var(--mono);font-size:13.5px;line-height:1.8;color:var(--code-fg);overflow-x:auto;margin-bottom:14px;white-space:pre;position:relative}.java-course .fill-code code{font-family:var(--mono);background:none}.java-course .fill-input{display:inline-block;min-width:90px;background:#f9e2af26;border:1px dashed #f9e2af;border-radius:5px;color:#f9e2af;font-family:var(--mono);font-size:13px;padding:1px 8px;outline:none;transition:all .2s;width:auto}.java-course .fill-input:focus{background:#f9e2af40;border-style:solid}.java-course .fill-input.correct{background:#a6e3a133;border-color:#a6e3a1;color:#a6e3a1}.java-course .fill-input.wrong{background:#f38ba826;border-color:#f38ba8;color:#f38ba8}.java-course .ex-check{background:var(--teal);color:#fff;border:none;cursor:pointer;font-family:var(--font);font-weight:600;padding:8px 20px;border-radius:9px;font-size:13px;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{display:block;animation:fadein .3s}.java-course .ex-result.ok{color:var(--teal)}.java-course .ex-result.no{color:#e63946}.java-course .complete-card{text-align:center;padding:40px 30px;background:linear-gradient(135deg,#e76f510f,#2a9d8f0f);border:1.5px dashed var(--primary-soft);border-radius:var(--radius);margin-top:30px}.java-course .complete-card .emoji{font-size:42px;margin-bottom:10px}.java-course .complete-card h3{font-size:20px;font-weight:800;margin-bottom:8px}.java-course .complete-card p{color:var(--ink-soft);font-size:14px;margin-bottom:18px}.java-course .complete-card .btn{font-size:14px}.java-course .lesson-nav{display:flex;justify-content:space-between;margin-top:36px;gap:12px}@media(max-width:860px){.java-course .app{grid-template-columns:1fr}.java-course aside.side{position:fixed;top:53px;left:0;width:280px;z-index:30;transform:translate(-100%);transition:.25s;box-shadow:0 8px 30px #2646532e;height:calc(100vh - 53px)}.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}}