/* ===== Shared Tutorial Styles ===== */
:root{--bg:#0f0f23;--bg-card:rgba(255,255,255,0.05);--bg-hover:rgba(255,255,255,0.1);--primary:#667eea;--secondary:#764ba2;--accent:#f093fb;--green:#43e97b;--red:#f5576c;--blue:#4facfe;--orange:#ffa726;--text:#fff;--text2:#a0aec0;--radius:14px;--transition:all 0.3s cubic-bezier(0.4,0,0.2,1)}
*,*::before,*::after{box-sizing:border-box}
body{font-family:'Inter',-apple-system,BlinkMacSystemFont,sans-serif;background:var(--bg);color:var(--text);line-height:1.8;overflow-x:hidden;margin:0;padding:0}
a{color:var(--primary);text-decoration:none}
a:hover{opacity:0.85}

/* Sidebar */
.sidebar{position:fixed;left:0;top:0;bottom:0;width:260px;background:rgba(15,15,35,0.98);border-right:1px solid rgba(255,255,255,0.08);padding:24px 0;overflow-y:auto;z-index:200;backdrop-filter:blur(20px);transition:transform 0.3s ease}
.sidebar-header{padding:0 20px 20px;border-bottom:1px solid rgba(255,255,255,0.08);margin-bottom:12px}
.sidebar-header h3{font-size:0.85rem;color:var(--primary);margin:0 0 4px}
.sidebar-header a{font-size:0.75rem;color:var(--text2)}
.phase-list{list-style:none;padding:0 12px;margin:0}
.phase-list li{margin-bottom:2px}
.phase-list a{display:flex;align-items:center;gap:10px;padding:10px 14px;border-radius:10px;color:var(--text2);font-size:0.85rem;transition:var(--transition)}
.phase-list a:hover,.phase-list a.active{background:var(--bg-hover);color:var(--text)}
.phase-list a.active{border-left:3px solid var(--primary);border-radius:6px 10px 10px 6px}
.phase-num{width:24px;height:24px;min-width:24px;border-radius:50%;background:var(--primary);display:flex;align-items:center;justify-content:center;font-size:0.7rem;font-weight:700}
.progress-bar{height:3px;background:rgba(255,255,255,0.1);border-radius:2px;margin:16px 20px 0;overflow:hidden}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--primary),var(--secondary));border-radius:2px;transition:width 0.5s;width:14%}

/* Mobile toggle */
.mobile-sidebar-toggle{display:none;position:fixed;top:16px;left:16px;z-index:300;width:44px;height:44px;border-radius:12px;background:var(--bg-card);border:1px solid rgba(255,255,255,0.1);color:var(--text);font-size:1.2rem;cursor:pointer;backdrop-filter:blur(10px)}
@media(max-width:1024px){
  .sidebar{transform:translateX(-100%)}
  .sidebar.open{transform:translateX(0)}
  .mobile-sidebar-toggle{display:flex;align-items:center;justify-content:center}
  .sidebar-overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,0.5);z-index:199}
  .sidebar-overlay.show{display:block}
}

/* Main content */
.main{padding:40px 48px 80px;margin-left:260px;max-width:960px;transition:margin 0.3s ease}
@media(max-width:1024px){.main{margin-left:0;padding:80px 24px 60px}}
@media(max-width:640px){.main{padding:80px 16px 40px}}

/* Top nav */
.nav-top{display:flex;align-items:center;gap:16px;padding:12px 0 32px;border-bottom:1px solid rgba(255,255,255,0.06);margin-bottom:40px;flex-wrap:wrap}
.nav-top .breadcrumb{color:var(--text2);font-size:0.85rem}
.nav-top .breadcrumb span{color:var(--text)}
.nav-top .difficulty{display:inline-flex;gap:4px;align-items:center;padding:4px 12px;border-radius:100px;font-size:0.8rem;font-weight:600;margin-left:auto}
.diff-beginner{background:rgba(67,233,123,0.15);color:var(--green)}
.diff-intermediate{background:rgba(240,147,251,0.15);color:var(--accent)}
.diff-advanced{background:rgba(245,87,108,0.15);color:var(--red)}

/* Hero */
.hero-block{margin-bottom:48px}
.hero-block h1{font-size:clamp(1.8rem,4vw,2.6rem);font-weight:800;line-height:1.2;margin:0 0 12px}
.hero-block .subtitle{font-size:1.1rem;color:var(--text2);max-width:700px;line-height:1.7;margin:0}
.meta-row{display:flex;gap:24px;margin-top:20px;flex-wrap:wrap}
.meta-item{display:flex;align-items:center;gap:8px;font-size:0.9rem;color:var(--text2)}
.meta-item i{color:var(--primary)}

/* TOC */
.toc{background:var(--bg-card);border-radius:var(--radius);padding:28px;margin-bottom:48px;border:1px solid rgba(255,255,255,0.05)}
.toc h3{font-size:1rem;color:var(--primary);margin:0 0 16px}
.toc ol{columns:2;column-gap:32px;padding-left:20px;margin:0}
.toc li{padding:6px 0;break-inside:avoid}
.toc a{color:var(--text2);font-size:0.9rem;transition:var(--transition)}
.toc a:hover{color:var(--primary)}
@media(max-width:640px){.toc ol{columns:1}.toc{padding:20px}}

/* Sections */
section{margin-bottom:48px;scroll-margin-top:24px}
section h2{font-size:1.6rem;font-weight:700;margin:0 0 20px;padding-bottom:12px;display:flex;align-items:center;gap:12px}
section h3{font-size:1.2rem;color:var(--accent);margin:28px 0 12px}
section h4{font-size:1.05rem;color:var(--primary);margin:20px 0 8px}
section p{color:var(--text2);margin:0 0 14px;line-height:1.85}
section ul,section ol{padding-left:24px;margin:0 0 16px}
section li{color:var(--text2);margin-bottom:8px;line-height:1.75}
section li strong{color:var(--text)}

/* Boxes */
.box{background:var(--bg-card);border:1px solid rgba(255,255,255,0.06);border-radius:var(--radius);padding:24px;margin:24px 0}
.box.info{border-left:4px solid var(--primary)}
.box.tip{border-left:4px solid var(--green);background:rgba(67,233,123,0.06)}
.box.tip h4{color:var(--green)}
.box.warning{border-left:4px solid var(--red)}
.box.warning h4{color:var(--red)}
.box h4{color:var(--primary);margin:0 0 10px;display:flex;align-items:center;gap:8px;font-size:1rem}

/* Formula */
.formula{background:rgba(0,0,0,0.4);border-radius:10px;padding:18px 24px;font-family:'JetBrains Mono',monospace;text-align:center;margin:16px 0;color:var(--green);font-size:1.1rem;overflow-x:auto}

/* Engineering note */
.eng-note{background:linear-gradient(135deg,rgba(102,126,234,0.06),rgba(118,75,162,0.06));border-radius:var(--radius);padding:20px;margin:20px 0;border:1px solid rgba(102,126,234,0.2)}
.eng-note strong{color:var(--accent)}

/* Code blocks */
pre{background:#0a0a14;border-radius:12px;padding:20px;overflow-x:auto;margin:16px 0;border:1px solid rgba(255,255,255,0.05);position:relative}
pre code{font-family:'JetBrains Mono',monospace;font-size:0.84rem;line-height:1.7;color:#e0e0e0}
.kw{color:#569cd6}.fn{color:#dcdcaa}.st{color:#ce9178}.cm{color:#6a9955}.nu{color:#b5cea8}.cl{color:#4ec9b0}
.copy-btn{position:absolute;top:12px;right:12px;padding:6px 12px;background:rgba(255,255,255,0.08);border:none;border-radius:6px;color:var(--text2);font-size:0.75rem;cursor:pointer;transition:var(--transition);z-index:5}
.copy-btn:hover{background:var(--primary);color:#fff}

/* Tables */
table{width:100%;border-collapse:collapse;margin:16px 0}
th,td{padding:10px 14px;text-align:left;border-bottom:1px solid rgba(255,255,255,0.06)}
th{color:var(--primary);font-weight:600;font-size:0.9rem}
td{color:var(--text2);font-size:0.9rem}

/* Checklists */
.checklist{list-style:none;padding:0}
.checklist li{padding:10px 0 10px 32px;position:relative;color:var(--text2)}
.checklist li::before{content:'☐';position:absolute;left:0;color:var(--primary);font-size:1.1rem}

/* Scroll animations */
.animate-in{opacity:0;transform:translateY(24px);transition:opacity 0.5s ease-out,transform 0.5s ease-out}
.animate-in.visible{opacity:1;transform:translateY(0)}

/* Section nav dots */
.section-nav{position:fixed;right:24px;top:50%;transform:translateY(-50%);z-index:50;display:flex;flex-direction:column;gap:8px}
.section-nav a{width:10px;height:10px;border-radius:50%;background:rgba(255,255,255,0.15);transition:var(--transition);cursor:pointer}
.section-nav a.active,.section-nav a:hover{background:var(--primary);transform:scale(1.3)}
@media(max-width:1200px){.section-nav{display:none}}

/* Page nav */
.page-nav{display:flex;justify-content:space-between;align-items:center;margin-top:48px;padding-top:24px;border-top:1px solid rgba(255,255,255,0.06);flex-wrap:wrap;gap:12px}
.page-nav a{display:inline-flex;align-items:center;gap:8px;padding:12px 20px;background:var(--bg-card);border-radius:10px;color:var(--text);font-size:0.9rem;transition:var(--transition)}
.page-nav a:hover{background:var(--bg-hover);transform:translateY(-2px)}
.page-nav .prev{text-align:left}.page-nav .next{text-align:right;margin-left:auto}

/* Search */
.search-container{position:fixed;top:16px;right:24px;z-index:300}
.search-btn{width:40px;height:40px;border-radius:10px;background:var(--bg-card);border:1px solid rgba(255,255,255,0.1);color:var(--text2);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:1rem;transition:var(--transition)}
.search-btn:hover{background:var(--bg-hover);color:var(--text)}
.search-modal{display:none;position:fixed;inset:0;background:rgba(0,0,0,0.85);z-index:400;backdrop-filter:blur(12px);flex-direction:column;align-items:center;padding-top:80px}
.search-modal.show{display:flex}
.search-input{width:90%;max-width:600px;padding:16px 20px;border-radius:14px;border:2px solid rgba(255,255,255,0.1);background:rgba(255,255,255,0.05);color:var(--text);font-size:1.1rem;outline:none;transition:var(--transition)}
.search-input:focus{border-color:var(--primary);background:rgba(255,255,255,0.08)}
.search-results{width:90%;max-width:600px;margin-top:24px;max-height:60vh;overflow-y:auto}
.search-result{padding:14px 18px;background:var(--bg-card);border-radius:10px;margin-bottom:8px;cursor:pointer;transition:var(--transition)}
.search-result:hover{background:var(--bg-hover)}
.search-result .title{font-weight:600;color:var(--text);margin-bottom:4px}
.search-result .snippet{font-size:0.85rem;color:var(--text2)}
.search-result .phase{font-size:0.75rem;color:var(--primary);float:right}
.search-close{position:absolute;top:24px;right:32px;font-size:1.8rem;color:var(--text2);cursor:pointer;background:none;border:none}

/* SVG diagrams */
.diagram-container{background:rgba(0,0,0,0.25);border-radius:var(--radius);padding:24px;margin:24px 0;text-align:center;overflow-x:auto}
.diagram-container svg{max-width:100%;height:auto}
.diagram-label{fill:var(--text2);font-size:11px;font-family:'Inter',sans-serif}
.diagram-title{fill:var(--text);font-size:12px;font-weight:600;font-family:'Inter',sans-serif}
.diagram-arrow{stroke:var(--primary);stroke-width:2;marker-end:url(#arrowhead)}
.diagram-line{stroke:rgba(255,255,255,0.15);stroke-width:1.5}


/* ===== Enhanced interactions ===== */
a{transition:all 0.2s ease}
.timeline-card:hover,a.timeline-card:hover{transform:translateY(-4px);box-shadow:0 12px 30px rgba(102,126,234,0.12)}
pre:hover{border-color:rgba(102,126,234,0.3)}
.box{transition:transform 0.2s ease,box-shadow 0.2s ease,border-color 0.2s ease}
.box:hover{border-color:rgba(255,255,255,0.12)}
.hero-block h1{letter-spacing:-0.02em}
section h2{letter-spacing:-0.01em}

/* Code block line numbers effect */
pre code{display:block;padding-left:0;tab-size:4}

/* Improved focus states */
a:focus-visible,button:focus-visible,input:focus-visible{outline:2px solid var(--primary);outline-offset:2px;border-radius:4px}

/* Smooth scrollbar */
::-webkit-scrollbar{width:6px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:rgba(255,255,255,0.12);border-radius:3px}
::-webkit-scrollbar-thumb:hover{background:rgba(255,255,255,0.25)}

/* Print styles */
@media print{
  .sidebar,.section-nav,.search-container,.mobile-sidebar-toggle{display:none!important}
  .main{margin-left:0!important;padding:20px!important}
  pre{border:1px solid #ddd;page-break-inside:avoid}
}