:root{--navy:#061b30;--navy2:#0b3154;--ink:#102d4e;--muted:#59718a;--line:#c9d9e8;--bg:#f2f6fb;--white:#fff;--gold:#efbd27;--cyan:#17a7b9;--blue:#1768d7;--green:#168461;--red:#b94236;--code:#071827}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;min-width:320px;background:var(--bg);color:var(--ink);font-family:Inter,Arial,sans-serif}button,input{font:inherit}a{color:inherit}.site-header{position:relative;z-index:50;min-height:72px;padding:7px clamp(16px,3vw,42px);display:flex;align-items:center;gap:24px;border-bottom:2px solid var(--gold);background:var(--navy);color:white}.brand{display:flex;align-items:center;gap:13px;margin-right:auto;text-decoration:none}.brand img{width:58px;height:56px;object-fit:contain;background:white}.brand span{font:700 30px Georgia,serif;color:#bdd5e9}.brand strong{color:var(--gold)}.site-header nav{display:flex;align-items:center;gap:4px}.site-header nav a{padding:12px 11px;border-radius:8px;color:#e6eff8;font-size:13px;font-weight:800;text-decoration:none}.site-header nav a:hover,.site-header nav a.active{background:#17344d;color:var(--gold)}.site-header .progress-link{margin-left:5px;background:var(--blue);color:white}.nav-toggle{display:none;width:45px;height:43px;border:1px solid #40627e;border-radius:8px;background:#0e2e4a;color:white;font-size:24px}main#courseTop{max-width:1560px;margin:auto;padding:clamp(24px,4vw,52px) clamp(14px,3vw,42px) 50px}.course-hero{display:grid;grid-template-columns:1.08fr .92fr;gap:28px;padding:clamp(25px,4vw,48px);overflow:hidden;border-radius:22px;background:linear-gradient(135deg,#061b30,#0b3b5d 62%,#11616a);box-shadow:0 20px 50px rgba(8,35,61,.18);color:white}.eyebrow,.section-label{margin:0;color:var(--gold);font-size:12px;font-weight:900;letter-spacing:.12em}.course-hero h1{max-width:780px;margin:12px 0;font:700 clamp(40px,5vw,68px)/1.03 Georgia,serif;letter-spacing:-.035em}.hero-copy{max-width:760px;color:#c7daeb;font-size:18px;line-height:1.65}.hero-actions{display:flex;flex-wrap:wrap;gap:11px;margin:24px 0}.button{display:inline-flex;min-height:47px;align-items:center;justify-content:center;padding:10px 18px;border:1px solid transparent;border-radius:10px;font-weight:900;text-decoration:none}.button.primary{background:var(--gold);color:#13283c}.button.secondary{border-color:#66859b;color:white}.hero-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:9px}.hero-stats div{padding:13px;border:1px solid #477087;border-radius:10px;background:rgba(255,255,255,.04)}.hero-stats strong,.hero-stats span{display:block}.hero-stats strong{color:#62dae3;font-size:24px}.hero-stats span{margin-top:4px;color:#bdd0df;font-size:11px}.java-flow{align-self:center;overflow:hidden;border:1px solid #50738b;border-radius:16px;background:#061522;box-shadow:0 14px 34px rgba(0,0,0,.2)}.flow-window{display:flex;gap:7px;padding:11px 14px;border-bottom:1px solid #31556e;color:#8fdfe7;font:700 11px monospace}.flow-window span{margin-right:auto}.flow-window i{width:9px;height:9px;border-radius:50%;background:#42647a}.java-flow pre{margin:0;padding:18px;overflow:auto;color:#ddebfa;font:500 12px/1.7 monospace}.java-flow em{color:#6cbcff;font-style:normal}.java-flow mark{background:none;color:#ffce62}.flow-arrow{padding:6px;color:#7ea7c6;text-align:center;font:700 10px monospace}.bytecode{margin:0 18px;padding:13px;border:1px dashed #4b6d84;border-radius:8px;color:#f6cd54;text-align:center;font:700 11px monospace}.runtime{display:grid;grid-template-columns:repeat(4,1fr);gap:7px;padding:17px}.runtime span{padding:10px 5px;border-radius:7px;background:#10334a;color:#87dfe7;font:700 10px monospace;text-align:center}.progress-card,.course-section,.course-cta{margin-top:24px;padding:clamp(20px,3vw,31px);border:1px solid var(--line);border-radius:17px;background:white}.progress-card{display:grid;grid-template-columns:1fr .75fr;gap:30px;align-items:center}.progress-card h2,.course-section>header h2,.course-cta h2{margin:7px 0;color:#0b3c70;font:700 clamp(27px,3vw,40px) Georgia,serif}.progress-card p,.course-section>header>p,.course-cta p{color:var(--muted);line-height:1.6}.progress-panel>div:first-child{display:flex;align-items:end;gap:7px}.progress-panel>div strong{color:var(--blue);font-size:32px}.progress-track{height:13px;margin:12px 0;overflow:hidden;border-radius:99px;background:#e2ebf3}.progress-track i{display:block;width:0;height:100%;background:linear-gradient(90deg,var(--blue),var(--cyan));transition:width .3s}.progress-panel footer{display:flex;justify-content:space-between}.progress-panel button{border:0;background:none;color:var(--red);cursor:pointer}.course-section>header{max-width:850px}.course-search{display:block;max-width:550px;margin-top:18px}.course-search span{display:block;margin-bottom:6px;color:#476680;font-size:12px;font-weight:800}.course-search input{width:100%;min-height:46px;padding:10px 13px;border:1px solid #aac2d8;border-radius:10px}.roadmap-part{margin-top:28px}.roadmap-part>header{display:flex;align-items:end;justify-content:space-between;gap:25px;padding-bottom:13px;border-bottom:2px solid #d6e3ef}.roadmap-part>header span{color:#906c04;font-size:11px;font-weight:900;letter-spacing:.08em}.roadmap-part>header h3{margin:5px 0 0;color:#0b3c70;font-size:25px}.roadmap-part>header p{max-width:620px;margin:0;color:var(--muted);line-height:1.5}.level-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-top:16px}.level-card{display:flex;min-width:0;flex-direction:column;padding:20px;border:1px solid var(--line);border-top:4px solid #62bdcc;border-radius:13px;background:#fbfdff;box-shadow:0 7px 18px rgba(12,55,91,.06)}.level-card[hidden]{display:none}.level-top{display:flex;align-items:center;justify-content:space-between}.level-top span{color:#906c04;font-size:11px;font-weight:900}.level-top i{display:grid;width:42px;height:42px;place-items:center;border-radius:10px;background:#e8f3ff;color:#1763c9;font:800 13px monospace}.level-card h4{margin:11px 0 7px;color:#103d69;font-size:19px}.level-card p{color:var(--muted);font-size:14px;line-height:1.55}.level-card a{margin-top:auto;padding:10px 0;color:#155ec2;font-weight:900;text-decoration:none}.level-card button{min-height:40px;margin-top:5px;border:1px solid #b8cce0;border-radius:8px;background:#f2f7fc;color:#294d70;font-size:12px;font-weight:850;cursor:pointer}.level-card button.done{border-color:#69bea0;background:#e7f7f0;color:#08714c}.empty-search{padding:22px;border-radius:10px;background:#fff4d3;color:#684d00}.value-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:13px;margin-top:20px}.value-grid article{padding:20px;border:1px solid var(--line);border-radius:12px;background:#f7fafd}.value-grid b{display:grid;width:40px;height:40px;place-items:center;border-radius:50%;background:var(--navy2);color:white}.value-grid h3{color:#103d69}.value-grid p{color:var(--muted);line-height:1.55}.course-cta{display:flex;align-items:center;justify-content:space-between;gap:24px;background:#eaf4fd}.site-footer{padding:25px clamp(18px,4vw,55px);display:grid;grid-template-columns:1fr auto;gap:13px 30px;background:var(--navy);color:#89abc8}.site-footer strong{color:var(--gold);font:700 25px Georgia,serif}.site-footer p{margin:5px 0}.site-footer nav{display:flex;flex-wrap:wrap;gap:15px}.site-footer a{color:#d9e8f5;text-decoration:none}.site-footer>p{grid-column:1/-1;padding-top:14px;border-top:1px solid #2d4e67;font-size:12px}
/* Lesson shell */.reading-progress{position:sticky;top:0;z-index:60;height:4px;background:#d5e1eb}.reading-progress i{display:block;width:0;height:100%;background:linear-gradient(90deg,var(--gold),var(--cyan))}.lesson-layout{display:grid;grid-template-columns:285px minmax(0,1fr);align-items:start}.lesson-sidebar{position:sticky;top:0;height:100vh;padding:20px 13px;overflow:auto;border-right:1px solid var(--line);background:white}.course-home{display:block;margin-bottom:13px;padding:12px;border-radius:8px;background:#eaf3fc;color:#145ba9;font-weight:900;text-decoration:none}.lesson-sidebar label span{display:block;margin:10px 3px 6px;color:#607b94;font-size:11px;font-weight:800}.lesson-sidebar input{width:100%;min-height:42px;padding:8px 10px;border:1px solid #b7cadc;border-radius:8px}.lesson-sidebar nav{margin-top:14px}.sidebar-part{margin:16px 9px 5px;color:#906c04;font-size:10px;font-weight:900;letter-spacing:.07em}.lesson-sidebar nav a{display:block;padding:8px 10px;border-radius:7px;color:#284b6a;font-size:12px;text-decoration:none}.lesson-sidebar nav a:hover,.lesson-sidebar nav a.active{background:#e8f2ff;color:#115fca}.sidebar-checkpoint{margin-top:20px;padding:13px;border-left:4px solid var(--cyan);border-radius:8px;background:#eef8fa}.sidebar-checkpoint span{display:block;color:#517188;font-size:9px;font-weight:900}.sidebar-checkpoint strong{display:block;margin-top:4px;font-size:12px}.lesson-menu{display:none}.sidebar-shade{display:none}.lesson-main{min-width:0;max-width:1270px;padding:28px clamp(18px,4vw,52px) 55px}.lesson-loading{padding:50px;text-align:center}.lesson-hero{display:grid;grid-template-columns:1.18fr .82fr;gap:23px;padding:clamp(24px,4vw,42px);border-radius:19px;background:linear-gradient(135deg,#071d33,#0c4263);color:white}.breadcrumb{display:flex;flex-wrap:wrap;gap:8px;color:#88b5d7;font-size:12px}.breadcrumb a{color:#bcdcff}.lesson-hero h1{margin:12px 0 8px;font:700 clamp(35px,4vw,55px)/1.06 Georgia,serif}.lesson-hero .lead{color:#c8daea;font-size:17px;line-height:1.65}.lesson-meta{display:flex;flex-wrap:wrap;gap:7px;margin-top:18px}.lesson-meta span{padding:7px 9px;border:1px solid #47728c;border-radius:7px;color:#bbd7e8;font-size:10px;font-weight:800}.outcome-card{padding:22px;border:1px solid #47728c;border-radius:14px;background:rgba(255,255,255,.05)}.outcome-card>span{color:var(--gold);font-size:10px;font-weight:900;letter-spacing:.09em}.outcome-card h2{margin:8px 0;font-size:21px}.outcome-card li{margin:8px 0;color:#d6e5ef;font-size:13px;line-height:1.45}.jump-bar{position:sticky;top:4px;z-index:30;display:flex;gap:7px;margin:16px 0;padding:9px;overflow:auto;border:1px solid var(--line);border-radius:12px;background:rgba(255,255,255,.96);box-shadow:0 6px 20px rgba(8,40,70,.08)}.jump-bar a{padding:8px 11px;border-radius:7px;color:#315777;font-size:11px;font-weight:900;white-space:nowrap;text-decoration:none}.jump-bar a:hover{background:#e8f2ff}.lesson-section{margin-top:18px;padding:clamp(20px,3vw,30px);overflow:hidden;border:1px solid var(--line);border-radius:15px;background:white}.section-heading span{color:#8c6903;font-size:10px;font-weight:900;letter-spacing:.09em}.section-heading h2{margin:6px 0 9px;color:#0b3c70;font:700 clamp(25px,3vw,36px) Georgia,serif}.section-heading p{color:var(--muted);line-height:1.6}.concept-block{margin-top:22px;padding-top:20px;border-top:1px solid #d8e4ee}.concept-block:first-of-type{border-top:0}.concept-block h3{margin:0 0 9px;color:#124c82;font-size:21px}.concept-block p,.concept-block li{color:#506b84;line-height:1.68}.concept-block li{margin:6px 0}.concept-note{margin-top:13px;padding:14px;border-left:4px solid var(--gold);border-radius:7px;background:#fff6d9;color:#5c4b16;line-height:1.55}.concept-table-wrap{overflow:auto;margin-top:15px}.concept-table{width:100%;min-width:590px;border-collapse:collapse}.concept-table th,.concept-table td{padding:11px;border:1px solid #cbd9e7;text-align:left}.concept-table th{background:#0d3d68;color:white;font-size:12px}.concept-table tr:nth-child(even){background:#f5f9fd}.example-card{margin-top:19px;overflow:hidden;border:1px solid #2c526e;border-radius:14px;background:var(--code)}.example-card header{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:13px 16px;background:#0d2b44;color:white}.example-card header span{color:#75d9e4;font-size:10px;font-weight:900}.copy-code{padding:7px 10px;border:1px solid #49708b;border-radius:7px;background:#123955;color:white;font-size:11px;cursor:pointer}.code-wrap{position:relative;overflow:auto}.code-wrap pre{margin:0;padding:18px;color:#dcebf8;font:500 13px/1.65 "Source Code Pro",monospace;white-space:pre}.example-card footer{padding:14px 16px;background:#0a2338;color:#b9d0e1;font-size:13px;line-height:1.55}.example-card footer pre{margin:8px 0 0;padding:10px;border-radius:7px;background:#04121e;color:#72e1ae;font:12px/1.5 monospace}.visualizer{display:grid;grid-template-columns:minmax(290px,.9fr) minmax(0,1.1fr);gap:14px;margin-top:20px}.trace-code,.trace-state{min-width:0;overflow:hidden;border-radius:12px;background:var(--code);color:white}.trace-code header,.trace-state header{padding:12px 15px;border-bottom:1px solid #2e526b;color:#79dae5;font-size:10px;font-weight:900}.trace-lines{max-height:380px;overflow:auto;padding:10px 0;font:500 12px/1.7 monospace}.trace-line{display:grid;grid-template-columns:34px 1fr;padding:2px 13px;color:#bcd1e1;white-space:pre}.trace-line b{color:#567d9b;text-align:right;margin-right:11px}.trace-line.active{background:#123956;color:white;box-shadow:inset 3px 0 var(--gold)}.trace-state{padding-bottom:15px}.trace-stage{min-height:190px;padding:20px}.trace-stage>span{color:var(--gold);font-size:10px;font-weight:900}.trace-stage h3{margin:8px 0}.trace-stage p{color:#c3d8e6;line-height:1.6}.state-box{margin-top:12px;padding:11px;border:1px solid #345d78;border-radius:8px;background:#0e2e47;color:#7fe2ea;font:12px/1.5 monospace;white-space:pre-wrap}.trace-controls{display:flex;flex-wrap:wrap;gap:7px;padding:0 15px}.trace-controls button{min-height:39px;padding:8px 11px;border:1px solid #47718d;border-radius:7px;background:#123852;color:white;font-size:11px;font-weight:800;cursor:pointer}.trace-controls button:first-child{border-color:var(--gold);background:var(--gold);color:#10273b}.trace-controls button:disabled{opacity:.4}.revision-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin-top:18px}.revision-grid div{padding:14px;border:1px solid #c8dae9;border-radius:9px;background:#f4f9fd;color:#3d5e7a;line-height:1.5}.revision-grid b{color:#0d4c85}.interview-list{display:grid;gap:9px;margin-top:18px}.interview-list details{border:1px solid #c8d9e7;border-radius:9px;background:#fbfdff}.interview-list summary{padding:14px;color:#173f64;font-weight:850;cursor:pointer}.interview-list p{margin:0;padding:0 15px 15px;color:#506b83;line-height:1.6}.practice-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin-top:18px}.practice-card{padding:17px;border:1px solid #cad9e7;border-radius:11px;background:#f8fbfe}.practice-card span{color:#8c6903;font-size:10px;font-weight:900}.practice-card h3{margin:7px 0;color:#154d7d}.practice-card p{color:#536f88;line-height:1.55}.practice-card details{color:#225d8f}.quiz-list{display:grid;gap:13px;margin-top:18px}.quiz-card{padding:18px;border:1px solid #cad9e7;border-radius:12px;background:#fbfdff}.quiz-card>span{color:#8c6903;font-size:10px;font-weight:900}.quiz-card h3{line-height:1.45}.quiz-options{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}.quiz-options button{padding:11px;border:1px solid #b8ccdf;border-radius:8px;background:white;color:#294e6e;text-align:left;cursor:pointer}.quiz-options button.correct{border-color:#59ad8b;background:#e6f7ef;color:#086846}.quiz-options button.wrong{border-color:#dc897c;background:#fff0ed;color:#972f24}.quiz-feedback{min-height:24px;margin:11px 0 0;color:#506b84;line-height:1.5}.quiz-score{margin-top:15px;padding:14px;border-radius:10px;background:var(--navy2);color:white;font-weight:900;text-align:center}.lesson-summary{display:grid;grid-template-columns:1.15fr .85fr;gap:18px}.summary-list li{margin:8px 0;color:#4f6a82;line-height:1.55}.complete-card{padding:20px;border-radius:12px;background:#e9f4fd}.complete-card span{color:#8c6903;font-size:10px;font-weight:900}.complete-card button{width:100%;min-height:45px;margin-top:12px;border:0;border-radius:8px;background:var(--blue);color:white;font-weight:900;cursor:pointer}.complete-card button.done{background:var(--green)}.lesson-navigation{display:flex;justify-content:space-between;gap:12px;margin-top:18px}.lesson-navigation a{flex:1;padding:14px;border:1px solid #b8ccde;border-radius:9px;background:white;color:#145da9;font-weight:900;text-decoration:none}.lesson-navigation a:last-child{text-align:right}
@media(max-width:1100px){.course-hero{grid-template-columns:1fr}.java-flow{width:100%}.level-grid{grid-template-columns:1fr 1fr}.value-grid{grid-template-columns:1fr 1fr}.lesson-layout{grid-template-columns:245px minmax(0,1fr)}.lesson-main{padding-inline:22px}.lesson-hero,.visualizer{grid-template-columns:1fr}}
@media(max-width:820px){.nav-toggle{display:block}.site-header nav{position:absolute;top:100%;right:0;left:0;display:none;align-items:stretch;flex-direction:column;padding:12px;background:var(--navy);border-bottom:2px solid var(--gold)}.site-header nav.open{display:flex}.site-header nav a{width:100%}.lesson-menu{position:sticky;top:4px;z-index:45;display:block;width:100%;min-height:44px;border:0;background:#0d3b62;color:white;font-weight:900}.lesson-layout{display:block}.lesson-sidebar{position:fixed;top:48px;bottom:0;left:0;z-index:80;width:min(88vw,320px);height:auto;transform:translateX(-105%);transition:.2s}.lesson-sidebar.open{transform:none}.sidebar-shade{position:fixed;inset:48px 0 0;z-index:70;background:rgba(4,19,33,.55)}.sidebar-shade:not([hidden]){display:block}.jump-bar{top:48px}.lesson-main{padding:16px 12px 40px}.progress-card{grid-template-columns:1fr}.roadmap-part>header{align-items:start;flex-direction:column}.course-cta{align-items:stretch;flex-direction:column}.site-footer{grid-template-columns:1fr}.site-footer>p{grid-column:auto}}
@media(max-width:560px){.brand img{width:48px;height:46px}.brand span{font-size:24px}.course-hero h1{font-size:38px}.hero-stats,.runtime,.level-grid,.value-grid,.revision-grid,.practice-grid,.quiz-options,.lesson-summary{grid-template-columns:1fr}.course-hero,.progress-card,.course-section{padding:20px 16px}.lesson-hero{padding:24px 18px}.lesson-section{padding:21px 16px}.visualizer{grid-template-columns:1fr}.trace-lines{max-height:300px}.lesson-navigation{flex-direction:column}.lesson-navigation a:last-child{text-align:left}.site-footer nav{flex-direction:column}.java-flow pre{font-size:10px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}