:root{
  --cs50-blue: #0b69ff;
  --text: #0f172a;
  --muted: #64748b;
  --bg: #ffffff;
  --code-bg: #f1f5f9;
  --font-sans: 'PT Sans', ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;
}
html,body{
  height:100%;
  margin:0;
  padding:0;
  font-family:var(--font-sans);
  color:var(--text);
  background:var(--bg);
  -webkit-font-smoothing:antialiased;
}
.site-header{
  border-bottom:1px solid #e6edf8;
  background:var(--bg);
  position:sticky;top:0;z-index:50;
}
.site-header-inner{max-width:1100px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;padding:12px 20px}
.site-title{font-weight:700;font-size:1.15rem;color:var(--text);text-decoration:none}
.site-nav a{margin-left:16px;color:var(--muted);text-decoration:none}
.site-nav a:hover{color:var(--text)}
.site-main{max-width:none;margin:0;padding:0;display:flex;gap:24px;align-items:flex-start}
.content-area{flex:1}
.sidebar{width:320px;flex-shrink:0}
.course-sidebar{width:320px;}
.sidebar .section-title{font-size:0.75rem;color:var(--muted);text-transform:uppercase;margin-bottom:8px}
.sidebar a{display:block;color:var(--muted);padding:6px 0;text-decoration:none}
.sidebar a.active{color:var(--text);font-weight:600}
/* Sidebar list + icon tweaks */
.sidebar-list{list-style:none;padding:0;margin:0}
.sidebar-list li{margin:4px 0;list-style:none}
.sidebar .icon{width:18px;height:18px;display:inline-block;vertical-align:middle}
.sidebar .label{vertical-align:middle}

/* Course sidebar - CS50-like */
.course-sidebar{background:#0f1724;color:#e6eef8;padding:12px;border-radius:0;height:100vh;overflow-y:auto;padding-right:6px;box-sizing:border-box}
.course-sidebar .site-title{color:#fff;font-weight:800;font-size:1.35rem;line-height:1.05;margin-bottom:6px}
.course-sidebar .site-subtitle{display:block;color:#9fb0cc;font-size:0.9rem;margin-bottom:12px}
.course-sidebar .sidebar-inner{display:flex;flex-direction:column;gap:18px}
.course-sidebar .section-title{color:#9fb0cc;font-size:0.72rem;text-transform:uppercase;letter-spacing:0.06em;margin-bottom:12px}
.course-sidebar .sidebar-nav{padding:6px 0}
.course-sidebar .sidebar-nav:not(:first-of-type){border-top:1px solid rgba(255,255,255,0.03);padding-top:8px;margin-top:8px}
.course-sidebar .sidebar-list a{display:block;color:#cbd5e1;padding:6px 8px;border-radius:0;text-decoration:none;font-size:0.98rem}
.course-sidebar .sidebar-list li{margin:6px 0}
.course-sidebar .week-link{display:flex;align-items:center;gap:12px}
.course-sidebar .week-badge{min-width:34px;height:34px;border-radius:6px;background:transparent;color:#9fb0cc;display:inline-flex;align-items:center;justify-content:center;font-weight:700;font-size:0.95rem;border:1px solid rgba(255,255,255,0.03)}
.course-sidebar .week-title{color:#e6eef8;display:block}
.course-sidebar .week-meta{display:block;color:#9fb0cc;font-size:0.8rem;margin-bottom:3px}
.course-sidebar .week-label{display:block;color:#e6eef8;font-weight:600;padding:6px 8px;border-radius:6px}
.course-sidebar .week-label:hover{background:rgba(255,255,255,0.02);color:#fff}
.course-sidebar .sidebar-list a:hover{background:rgba(255,255,255,0.03);color:#fff;text-decoration:none}
.course-sidebar .sidebar-list a[aria-current="page"]{background:transparent;color:#fff;font-weight:700;border-left:3px solid var(--cs50-blue);padding-left:10px}
.course-sidebar .week-link[aria-current="page"] .week-badge{background:var(--cs50-blue);color:#fff}
.course-sidebar .week-link[aria-current="page"] .week-title{font-weight:700}


/* social icons inline (single row) */
.sidebar-social{display:flex;flex-direction:row;gap:8px;margin-bottom:12px;align-items:center;flex-wrap:wrap}
.sidebar-social .social-link{width:36px;height:36px;border-radius:6px;display:inline-flex;align-items:center;justify-content:center;background:transparent;color:#e6eef8;text-decoration:none;border:1px solid rgba(255,255,255,0.03)}
.sidebar-social .social-link:hover{background:transparent;color:var(--cs50-blue);border-color:rgba(255,255,255,0.03)}
.sidebar-social svg{width:18px;height:18px}

/* contact/donate and quick links */
.sidebar-contact{padding:12px;border-radius:8px;background:linear-gradient(180deg,rgba(255,255,255,0.02),transparent);border:1px solid rgba(255,255,255,0.03);display:flex;flex-direction:column;gap:8px}
.sidebar-contact .instructor{font-weight:700;color:#fff}
.sidebar-contact .contact-email{font-size:0.9rem;color:#9fb0cc}
.donate-link{display:inline-flex;align-items:center;gap:8px;background:transparent;padding:4px 6px;border-radius:6px;color:#fff;border:none;text-decoration:none;font-weight:700;font-size:0.95rem}
.donate-link:hover{background:var(--cs50-blue);border-color:var(--cs50-blue)}

.quick-links{display:flex;flex-direction:column;gap:6px}
.quick-links a{display:flex;align-items:center;gap:10px;color:#cbd5e1;text-decoration:none;padding:8px 8px;border-radius:6px}
.quick-links a:hover{background:rgba(255,255,255,0.03);color:#fff}
.quick-links .fa{width:18px;text-align:center}

/* final project highlight */
.final-project{margin-top:10px;padding:8px;border-radius:8px;background:rgba(255,255,255,0.02);border:1px solid rgba(255,255,255,0.03);font-weight:700;color:#ffdce0}
.final-project a{color:#ffdce0;text-decoration:none}
.final-project a:hover{text-decoration:underline;color:#fff}

/* Tool link layout */
.tool-link{display:flex;align-items:center;gap:10px}
.tool-link .icon{background:rgba(255,255,255,0.02);width:34px;height:34px;border-radius:6px;display:inline-flex;align-items:center;justify-content:center}
.tool-link .icon svg{width:18px;height:18px;color:inherit}
.tool-link .label{font-weight:600}
..tool-link .icon-emoji{display:inline-flex;width:34px;height:34px;border-radius:6px;align-items:center;justify-content:center;background:rgba(255,255,255,0.02);font-size:18px}

/* icon badges for tools */
.icon-badge{display:inline-flex;width:34px;height:34px;border-radius:6px;align-items:center;justify-content:center;background:rgba(255,255,255,0.02);font-weight:800;color:var(--cs50-blue);font-size:0.85rem}
.icon-badge.code{background:rgba(0,120,212,0.15);color:#0078d4}
.icon-badge.code svg{width:16px;height:16px}
.icon-badge.duck{background:rgba(255,213,0,0.15);font-size:1.2rem}
.icon-badge.gradebook{background:rgba(46,204,113,0.15);color:#2ecc71}
.icon-badge.gradebook svg{width:16px;height:16px}
.icon-badge.syllabus{background:rgba(155,89,182,0.15);color:#9b59b6}
.icon-badge.syllabus svg{width:16px;height:16px}

/* Courses (bottom) styling smaller/muted */
.course-sidebar .courses-list a{color:#9fb0cc;font-size:0.95rem;padding:8px 6px}
.course-sidebar .courses-list a:hover{color:#fff;background:rgba(255,255,255,0.02)}

/* ensure course sidebar sits nicely on small screens */
.course-page-layout{width:100%;margin:0;padding:0}
.course-container{display:flex;gap:24px;align-items:flex-start;height:100vh;overflow:hidden}
.course-content{flex:1;padding:20px;box-sizing:border-box;height:100vh;overflow-y:auto}
.course-list{list-style:none;padding:0;margin:0}
.course-list li{border-bottom:1px solid rgba(255,255,255,0.03);padding:12px 0}

@media (max-width:900px){
  .course-sidebar{padding:12px;margin-bottom:12px;height:auto}
  .sidebar-social{justify-content:flex-start}
  .mobile-social{display:flex;gap:8px;margin-bottom:10px}
  .mobile-social .social-link{display:inline-flex;align-items:center;justify-content:center;width:36px;height:36px}
  .course-container{flex-direction:column;height:auto}
  .course-content{height:auto;overflow:visible;padding:16px}
}


/* Typography & Markdown content styles */
pre{background:var(--code-bg);padding:1rem;border-radius:6px;overflow:auto;margin:1.5rem 0;font-size:0.9rem}
code{background:var(--code-bg);padding:0.18rem 0.35rem;border-radius:4px;font-family:monospace}
pre code{background:none;padding:0}
h1{color:var(--text);font-weight:700;font-size:2rem;margin:2rem 0 1rem 0;border-bottom:3px solid var(--cs50-blue);padding-bottom:0.5rem}
h2{color:var(--text);font-weight:700;font-size:1.5rem;margin:1.75rem 0 0.75rem 0;border-bottom:2px solid #e0e7ff;padding-bottom:0.25rem}
h3{color:var(--text);font-weight:700;font-size:1.25rem;margin:1.5rem 0 0.5rem 0}
h4,h5,h6{color:var(--text);font-weight:600;margin:1rem 0 0.5rem 0}
p{line-height:1.75;margin:1rem 0}
ul,ol{line-height:1.75;margin:1.25rem 0;padding-left:2rem}
li{margin:0.5rem 0}
a{color:var(--cs50-blue);text-decoration:underline;cursor:pointer}
.course-sidebar a{color:inherit;text-decoration:none}
a:hover{color:#0556d4}
.prose a{text-decoration:underline}
img{max-width:100%;height:auto;margin:1.5rem 0;border-radius:8px;border:1px solid #e2e8f0}
blockquote{border-left:4px solid var(--cs50-blue);padding-left:1rem;margin:1.5rem 0;color:var(--muted);font-style:italic}
table{border-collapse:collapse;width:100%;margin:1.5rem 0}
table th,table td{border:1px solid #cbd5e1;padding:0.75rem;text-align:left}
table th{background:#f1f5f9;font-weight:600}
hr{border:none;border-top:2px solid #e2e8f0;margin:2rem 0}
/* Harvard CS50-inspired content style */
.prose{max-width:800px;margin:0 auto;font-size:1.08rem;line-height:1.8;color:var(--text);}
.prose h1{font-size:2.2rem;margin:2.2rem 0 1.2rem 0;font-weight:800;color:var(--cs50-blue);border-bottom:4px solid var(--cs50-blue);padding-bottom:0.4rem;letter-spacing:-1px;}
.prose h2{font-size:1.5rem;margin:1.7rem 0 1rem 0;font-weight:700;color:var(--text);border-bottom:2px solid #e0e7ff;padding-bottom:0.2rem;}
.prose h3{font-size:1.15rem;margin:1.2rem 0 0.7rem 0;font-weight:700;color:var(--text);}
.prose h4,.prose h5,.prose h6{font-weight:600;margin:1rem 0 0.5rem 0;color:var(--muted);}
.prose p{margin:1.1rem 0;}
.prose ul,.prose ol{margin:1.2rem 0 1.2rem 1.5rem;padding:0;}
.prose li{margin:0.5rem 0;}
.prose a{color:var(--cs50-blue);text-decoration:underline;word-break:break-word;}
.prose a:hover{color:#0556d4;text-decoration:underline;}
.prose img{max-width:100%;height:auto;margin:1.5rem 0;border-radius:10px;border:1.5px solid #e2e8f0;box-shadow:0 2px 8px 0 #e0e7ff44;}
.prose blockquote{border-left:4px solid var(--cs50-blue);padding-left:1.2rem;margin:1.5rem 0;color:var(--muted);font-style:italic;background:#f8fafc;}
.prose pre{background:var(--code-bg);padding:1.1rem 1.2rem;border-radius:8px;overflow:auto;margin:1.5rem 0;font-size:0.98rem;}
.prose code{background:var(--code-bg);padding:0.18rem 0.35rem;border-radius:4px;font-family:monospace;}
.prose hr{border:none;border-top:2px solid #e2e8f0;margin:2rem 0;}
.prose table{border-collapse:collapse;width:100%;margin:1.5rem 0;}
.prose th,.prose td{border:1px solid #cbd5e1;padding:0.75rem;text-align:left;}
.prose th{background:#f1f5f9;font-weight:600;}
/* Sidebar spacing improvements */
.sidebar-nav{margin-bottom:1rem}
.sidebar-nav:last-child{margin-bottom:0}
.sidebar-list{list-style:none;padding:0;margin:0.5rem 0;padding-left:0}
.sidebar-list li{margin:8px 0;list-style:none;margin-left:0}
.course-sidebar ul,.course-sidebar ol{margin:0;padding:0;list-style:none}
.weeks-list{padding-left:0;margin:0;list-style:none}
.weeks-list li{list-style:none;margin:6px 0;padding-left:0}
.weeks-list li::marker{display:none}
.course-sidebar .week-title{font-size:0.98rem;color:#e6eef8}
.sidebar-list a{padding:8px 0;border-radius:4px;transition:background-color 0.2s}
.sidebar-list a:hover{background-color:#f1f5f9;color:var(--text)}
.sidebar .icon{width:18px;height:18px;display:inline-block;vertical-align:middle;margin-right:8px}
.sidebar .label{vertical-align:middle;display:inline}
.sidebar .section-title{margin-bottom:12px}
/* Course content spacing */
.course-content{padding:0}
.content-wrapper{max-width:800px}
/* small responsive adjustments */
@media (max-width:900px){
  .site-main{flex-direction:column;padding:0 14px}
  .sidebar{width:100%}
  h1{font-size:1.75rem}
  h2{font-size:1.25rem}
}

/* custom scrollbar for sidebar */
.course-sidebar::-webkit-scrollbar{width:10px}
.course-sidebar::-webkit-scrollbar-track{background:transparent}
.course-sidebar::-webkit-scrollbar-thumb{background:rgba(255,255,255,0.06);border-radius:999px}
.course-sidebar::-webkit-scrollbar-thumb:hover{background:rgba(255,255,255,0.12)}