/* SanjibSikderWeb – minimal design system */
:root{
  --bg:#0b0b0c;         /* dark base */
  --card:#111114;
  --text:#e9e9ea;
  --muted:#b9b9c0;
  --primary:#5b8cff;    /* accent */
  --ring:#2a2a33;
  --radius:16px;
  --shadow:0 8px 24px rgba(0,0,0,.2);
}

@media (prefers-color-scheme: light){
  :root{
    --bg:#fafafa; --card:#ffffff; --text:#111114; --muted:#52525b;
    --primary:#2563eb; --ring:#e5e7eb;
  }
}

*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{
  font:16px/1.65 system-ui, -apple-system, Segoe UI, Roboto, Inter, "Helvetica Neue", Arial, sans-serif;
  color:var(--text); background:var(--bg);
}

.container{max-width:960px;margin:48px auto;padding:0 20px}
header.site{
  position:sticky; top:0; backdrop-filter:saturate(180%) blur(8px);
  background:color-mix(in oklab, var(--bg) 85%, transparent);
  border-bottom:1px solid var(--ring);
}
.nav{display:flex;align-items:center;justify-content:space-between;max-width:960px;margin:0 auto;padding:14px 20px}
.brand{font-weight:700;letter-spacing:.2px}
nav a{color:var(--text); text-decoration:none; margin-left:14px; opacity:.85}
nav a:hover{opacity:1}

.hero{
  padding:64px 0 28px; margin-top:12px;
  background:
    radial-gradient(1200px 400px at 10% -10%, color-mix(in oklab, var(--primary) 45%, transparent) 0%, transparent 60%),
    radial-gradient(900px 300px at 100% 0%, color-mix(in oklab, var(--primary) 30%, transparent) 0%, transparent 60%);
}
.hero h1{font-size:38px; line-height:1.15; margin:0 0 10px}
.hero p{color:var(--muted); margin:0}

.btn{
  display:inline-block; padding:10px 14px; border-radius:12px; text-decoration:none;
  border:1px solid var(--ring); color:var(--text); transition:.2s transform, .2s background;
  background:linear-gradient(180deg, color-mix(in oklab, var(--card) 80%, transparent), var(--card));
}
.btn:hover{transform:translateY(-1px)}
.btn.primary{border-color:color-mix(in oklab, var(--primary) 40%, var(--ring));
  background:linear-gradient(180deg, color-mix(in oklab, var(--primary) 30%, var(--card)), var(--card));
}

.section{margin:36px 0}
.card{
  background:var(--card); border:1px solid var(--ring); border-radius:var(--radius);
  padding:18px; box-shadow:var(--shadow)
}
.grid{display:grid; gap:16px}
.grid.cols-2{grid-template-columns:1fr}
@media (min-width:720px){.grid.cols-2{grid-template-columns:1fr 1fr}}
.small{color:var(--muted); font-size:14px}

.list{padding-left:18px; margin:10px 0}
.list li{margin:6px 0}

footer.site{border-top:1px solid var(--ring); margin-top:48px}
footer.site .container{padding:20px}
kbd{
  font:12px ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  background:var(--ring); padding:2px 6px; border-radius:6px; border:1px solid color-mix(in oklab, var(--ring) 70%, transparent)
}

/* avatar block for about page */
.avatar{
  width:120px; height:120px; border-radius:20px; object-fit:cover;
  border:1px solid var(--ring); box-shadow:var(--shadow)
}

/* Roadmap page layout overrides (scoped) */
body.roadmap {
  background: #000;
  color: #eaeaea;
  margin: 0;
  min-height: 100vh;
  max-width: none;      
  padding: 24px 0;
}

/* Keep roadmap content readable width */
body.roadmap #content,
body.roadmap .markdown-body,
body.roadmap main {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 16px;
}

/* Bright headings */
body.roadmap h1, 
body.roadmap h2, 
body.roadmap h3 { 
  color: #eaeaea; 
}

/* Center all top-level content on the roadmap page */
body.roadmap > :not(script):not(style) {
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 16px;
  padding-right: 16px;
}

/* Roadmap checklist – Force Green checkboxes */
body.roadmap input[type=checkbox],
body.roadmap input[type=checkbox][disabled] {
  -webkit-appearance: none !important;
  -moz-appearance: none !important;
  appearance: none !important;
  width: 18px;
  height: 18px;
  border: 2px solid #aaa;
  border-radius: 3px;
  cursor: pointer;
  vertical-align: middle;
  margin-right: 6px;
  position: relative;
  background: #000;
}

body.roadmap input[type=checkbox]:checked,
body.roadmap input[type=checkbox][disabled]:checked {
  background-color: #2ecc71 !important; /* green */
  border-color: #2ecc71 !important;
}

body.roadmap input[type=checkbox]:checked::after,
body.roadmap input[type=checkbox][disabled]:checked::after {
  content: "✓";
  position: absolute;
  left: 2px;
  top: -2px;
  color: white;
  font-size: 14px;
  line-height: 18px;
}

/* Roadmap page heading style */
body.roadmap h1:first-of-type {
  text-align: center;
  font-size: 2em;
  margin-bottom: 1.2em;
  color: #ffffff; /* bright white */
  text-transform: uppercase;
  letter-spacing: 1px;
}


.hero .muted {
  font-size: 1.1rem;
  opacity: 0.85;
  margin: 0.5rem 0;
}
.hero h1 {
  margin-bottom: 0.4em; /* smaller gap below main line */
}

.hero p {
  margin: 0.2em 0;     /* tighter spacing for sub + identity lines */
}

/* General links (exclude buttons) */
a:not(.btn) {
  color: #2aa8ff;          /* bright blue for unvisited */
  text-decoration: none;
}
a:not(.btn):visited {
  color: #d28cff;          /* violet for visited */
}
a:not(.btn):hover,
a:not(.btn):focus {
  color: #78c6ff;          /* lighter blue on hover */
  text-decoration: underline;
}

/* Roadmap link special highlight */
a[href="/roadmap/"] {
  color: #20c997;          /* teal (unvisited) */
}
a[href="/roadmap/"]:visited {
  color: #9be3d0;          /* softer mint-teal when visited */
}
a[href="/roadmap/"]:hover,
a[href="/roadmap/"]:focus {
  color: #38e1aa;          /* brighter teal on hover */
  text-decoration: underline;
}


.site-nav a.active {
  font-weight: bold;        /* make it stand out */
  border-bottom: 2px solid currentColor; /* underline effect */
}


/* Two-column layout for lessons */
.lesson-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 2rem;
}
.lesson-sidebar {
  position: sticky;
  top: 1rem;
  max-height: calc(100vh - 2rem);
  overflow: auto;
}
@media (max-width: 900px) {
  .lesson-layout { display: block; }
  .lesson-sidebar { position: static; margin-bottom: 1rem; max-height: none; }
}

.lesson-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 2rem;
}
.lesson-sidebar { position: sticky; top: 1rem; max-height: calc(100vh - 2rem); overflow: auto; }
.lesson-sidebar-nav h3 { margin-top: 0; font-size: 1rem; }
.lesson-chapters { list-style: none; margin: 0 0 1rem 0; padding: 0; }
.lesson-chapters li { margin: 0.25rem 0; }
.lesson-chapters li.active > a { font-weight: 600; border-left: 3px solid currentColor; padding-left: .5rem; }
.lesson-toc { list-style: none; margin: 0; padding: 0; }
.lesson-toc li { margin: 0.25rem 0; }
.lesson-toc li.h3 { margin-left: 1rem; font-size: 0.95em; }
.lesson-prevnext { margin: 0.75rem 0 1rem; display: flex; justify-content: space-between; gap: .5rem; }
@media (max-width: 900px) { .lesson-layout { display: block; } .lesson-sidebar { position: static; max-height: none; margin-bottom: 1rem; } }