@import url('https://fonts.googleapis.com/css2?family=Hind+Siliguri:wght@400;500;600;700&family=JetBrains+Mono:wght@400;600&display=swap');

/* ==========================================================================
   DSA Study Site — shared chrome + page styles
   All selectors are prefixed .ds- so they never collide with the styles
   already inside the four original topic pages.
   ========================================================================== */

:root{
  --ds-ink:#1b2430;
  --ds-ink-soft:#5a6875;
  --ds-line:#dde4ec;
  --ds-primary:#1a5276;
  --ds-primary-lt:#eaf3fb;
  --ds-accent:#117864;
  --ds-accent-lt:#e6f7f3;
  --ds-warn:#a04000;
  --ds-warn-lt:#fdf0e5;
  --ds-purple:#5b2c6f;
  --ds-purple-lt:#f3e9f7;
  --ds-gold:#8a6d0b;
  --ds-gold-lt:#fffbea;
  --ds-green:#1e8449;
  --ds-green-lt:#eafaf1;
  --ds-bar:#16222f;
  --ds-bar-2:#22323f;
}

/* ---------- top nav (injected at the very top of every page body) -------- */
.ds-nav{
  font-family:'Hind Siliguri','Noto Sans Bengali','Segoe UI',sans-serif;
  background:var(--ds-bar);
  color:#fff;
  border-radius:10px;
  max-width:1120px;
  margin:14px auto 26px;
  padding:12px 16px 10px;
  box-shadow:0 10px 26px -18px rgba(0,0,0,.55);
  line-height:1.5;
}
.ds-nav a{text-decoration:none;}
.ds-nav-top{
  display:flex;align-items:center;justify-content:space-between;
  gap:12px;flex-wrap:wrap;padding-bottom:10px;
  border-bottom:1px solid rgba(255,255,255,.13);
}
.ds-brand{
  color:#fff;font-weight:700;font-size:15px;letter-spacing:.2px;
  display:flex;align-items:center;gap:9px;
}
.ds-brand span.ds-dot{
  width:9px;height:9px;border-radius:50%;background:#4fc3a1;flex:none;
}
.ds-brand small{
  display:block;font-weight:400;font-size:11.5px;color:#8fa3b5;letter-spacing:.3px;
}
.ds-nav-actions{display:flex;gap:8px;align-items:center;}
.ds-nav-actions a{
  color:#cfe0ee;font-size:12.5px;font-weight:600;
  border:1px solid rgba(255,255,255,.2);border-radius:6px;padding:5px 11px;
  transition:background .15s,color .15s;
}
.ds-nav-actions a:hover{background:rgba(255,255,255,.12);color:#fff;}

.ds-chips{
  display:flex;gap:6px;overflow-x:auto;padding:10px 2px 3px;
  scrollbar-width:thin;
}
.ds-chips::-webkit-scrollbar{height:5px;}
.ds-chips::-webkit-scrollbar-thumb{background:#3c5063;border-radius:4px;}
.ds-chip{
  flex:none;display:flex;align-items:center;gap:6px;
  background:var(--ds-bar-2);color:#c3d4e2;
  font-size:12.5px;font-weight:500;
  padding:6px 11px;border-radius:20px;white-space:nowrap;
  border:1px solid transparent;transition:background .15s,color .15s;
}
.ds-chip b{
  font-size:10.5px;font-weight:700;color:#7b93a8;
  font-family:'JetBrains Mono',monospace;
}
.ds-chip:hover{background:#2e4152;color:#fff;}
.ds-chip.ds-on{background:#4fc3a1;color:#0d2119;border-color:#7fe0c4;font-weight:700;}
.ds-chip.ds-on b{color:#0d2119;opacity:.65;}
.ds-chip.ds-new::after{
  content:'নতুন';font-size:9px;background:#e07a3f;color:#fff;
  padding:1px 5px;border-radius:8px;font-weight:700;
}

/* ---------- bottom pager -------------------------------------------------- */
.ds-pager{
  font-family:'Hind Siliguri','Noto Sans Bengali','Segoe UI',sans-serif;
  max-width:1120px;margin:46px auto 10px;
  display:flex;gap:12px;align-items:stretch;flex-wrap:wrap;
}
.ds-pager a{
  flex:1 1 240px;min-width:0;text-decoration:none;
  border:1px solid var(--ds-line);border-radius:10px;
  padding:13px 16px;background:#fff;color:var(--ds-ink);
  transition:border-color .15s,box-shadow .15s,transform .15s;
}
.ds-pager a:hover{
  border-color:var(--ds-primary);box-shadow:0 8px 20px -14px rgba(26,82,118,.7);
  transform:translateY(-1px);
}
.ds-pager small{
  display:block;font-size:11.5px;color:var(--ds-ink-soft);
  text-transform:uppercase;letter-spacing:1px;margin-bottom:3px;
}
.ds-pager b{font-size:15px;font-weight:600;}
.ds-pager .ds-next{text-align:right;}
.ds-pager .ds-dead{opacity:.4;pointer-events:none;}

.ds-foot{
  font-family:'Hind Siliguri','Noto Sans Bengali',sans-serif;
  max-width:1120px;margin:0 auto;padding:18px 4px 30px;
  text-align:center;color:#8b98a5;font-size:12.5px;
  border-top:1px solid var(--ds-line);
}
.ds-foot a{color:var(--ds-primary);text-decoration:none;font-weight:600;}

/* ---------- floating quick-jump ------------------------------------------ */
.ds-fab{
  position:fixed;right:16px;bottom:16px;z-index:9999;
  display:flex;gap:6px;
  font-family:'Hind Siliguri','Noto Sans Bengali',sans-serif;
}
.ds-fab a{
  display:flex;align-items:center;justify-content:center;
  min-width:40px;height:40px;padding:0 12px;
  background:var(--ds-bar);color:#fff;text-decoration:none;
  border-radius:20px;font-size:14px;font-weight:600;
  box-shadow:0 8px 22px -10px rgba(0,0,0,.6);
  transition:background .15s;
}
.ds-fab a:hover{background:#2e4152;}
.ds-fab a.ds-dead{opacity:.3;pointer-events:none;}
@media print{.ds-fab,.ds-chips,.ds-nav-actions{display:none !important;}}

/* ==========================================================================
   Page styles — used by the newly written topic pages
   ========================================================================== */
body.ds-page{
  font-family:'Hind Siliguri','Noto Sans Bengali','Segoe UI',Arial,sans-serif;
  background:#fbfcfd;color:var(--ds-ink);
  line-height:1.78;font-size:16.5px;
  margin:0;padding:0 20px 40px;
}
body.ds-page .ds-wrap{max-width:1120px;margin:0 auto;}

.ds-hero{
  background:linear-gradient(135deg,#16222f,#1a5276);
  color:#fff;border-radius:14px;padding:30px 32px;margin-bottom:8px;
}
.ds-hero .ds-eyebrow{
  font-size:12px;letter-spacing:2px;text-transform:uppercase;
  color:#8fd8c4;font-weight:700;margin-bottom:8px;
}
.ds-hero h1{margin:0 0 10px;font-size:31px;line-height:1.3;font-weight:700;}
.ds-hero p{margin:0;color:#c2d5e4;font-size:15.5px;max-width:70ch;}
.ds-tagrow{display:flex;gap:8px;flex-wrap:wrap;margin-top:16px;}
.ds-tag{
  background:rgba(255,255,255,.13);border:1px solid rgba(255,255,255,.22);
  padding:4px 12px;border-radius:16px;font-size:12.5px;font-weight:600;
}
.ds-tag.ds-hot{background:#e07a3f;border-color:#f0a274;}

body.ds-page h2{
  color:#fff;background:var(--ds-primary);
  padding:11px 18px;border-radius:8px;font-size:20px;
  margin:42px 0 16px;font-weight:600;scroll-margin-top:14px;
}
body.ds-page h3{
  color:var(--ds-accent);border-left:5px solid var(--ds-accent);
  padding-left:11px;font-size:17px;margin:26px 0 10px;font-weight:600;
}
body.ds-page h4{font-size:15.5px;margin:18px 0 6px;color:var(--ds-primary);}
body.ds-page p{margin:10px 0;}
body.ds-page ul,body.ds-page ol{padding-left:26px;margin:10px 0;}
body.ds-page li{margin-bottom:7px;}
body.ds-page code{
  font-family:'JetBrains Mono','Consolas',monospace;font-size:.9em;
  background:#eef2f6;padding:1.5px 6px;border-radius:4px;color:#123;
}
body.ds-page b,body.ds-page strong{font-weight:600;}

.ds-toc{
  background:#fff;border:1px solid var(--ds-line);border-radius:12px;
  padding:16px 20px;margin:22px 0 6px;
}
.ds-toc-title{
  font-size:12px;letter-spacing:1.6px;text-transform:uppercase;
  color:var(--ds-ink-soft);font-weight:700;margin-bottom:10px;
}
.ds-toc ol{margin:0;padding-left:0;list-style:none;
  columns:2;column-gap:26px;}
.ds-toc li{margin-bottom:5px;break-inside:avoid;}
.ds-toc a{
  color:var(--ds-ink);text-decoration:none;font-size:14.5px;
  border-bottom:1px solid transparent;
}
.ds-toc a:hover{color:var(--ds-primary);border-bottom-color:var(--ds-primary);}
.ds-toc a b{
  font-family:'JetBrains Mono',monospace;font-size:12px;
  color:var(--ds-ink-soft);margin-right:7px;
}
@media(max-width:720px){.ds-toc ol{columns:1;}}

/* ---- boxes -------------------------------------------------------------- */
.ds-q{
  background:var(--ds-primary-lt);border:2px solid var(--ds-primary);
  border-radius:10px;padding:18px 22px;font-weight:600;font-size:16px;
}
.ds-q .ds-qn{
  display:inline-block;background:var(--ds-primary);color:#fff;
  font-size:12px;padding:2px 10px;border-radius:12px;margin-bottom:8px;
  font-weight:700;letter-spacing:.5px;
}
.ds-concept{
  background:var(--ds-accent-lt);border-left:5px solid var(--ds-accent);
  border-radius:7px;padding:14px 19px;margin:12px 0;
}
.ds-def{
  background:var(--ds-purple-lt);border:2px dashed var(--ds-purple);
  border-radius:9px;padding:15px 20px;margin:12px 0;
}
.ds-def em{font-style:normal;color:var(--ds-purple);font-weight:600;}
.ds-warn{
  background:var(--ds-warn-lt);border-left:5px solid var(--ds-warn);
  border-radius:7px;padding:14px 19px;margin:12px 0;
}
.ds-step{
  background:#fff;border:1px solid var(--ds-line);
  border-left:5px solid var(--ds-primary);
  border-radius:7px;padding:14px 19px;margin:16px 0;
}
.ds-why{
  background:var(--ds-gold-lt);border-left:4px solid #d4ac0d;
  border-radius:5px;padding:9px 14px;margin-top:9px;font-size:14.8px;
}
.ds-why b{color:var(--ds-gold);}
.ds-ans{
  background:var(--ds-green-lt);border:3px solid var(--ds-green);
  border-radius:10px;padding:18px 20px;font-size:17.5px;font-weight:700;
  color:#145a32;text-align:center;margin:16px 0;
}
.ds-ans small{display:block;font-weight:500;font-size:13.5px;color:#1e7c46;margin-top:6px;}
.ds-viva{
  background:var(--ds-purple-lt);border-left:4px solid var(--ds-purple);
  border-radius:6px;padding:11px 18px;margin-bottom:9px;
}
.ds-viva b{color:var(--ds-purple);}

/* ---- code + ascii ------------------------------------------------------- */
body.ds-page pre{
  background:#1e272e;color:#d7ecff;padding:17px 19px;border-radius:9px;
  overflow-x:auto;font-size:14px;line-height:1.6;
  font-family:'JetBrains Mono','Consolas',monospace;
}
.ds-ascii{
  background:#f4f6f7;border:1px solid var(--ds-line);border-radius:9px;
  padding:16px 18px;font-family:'JetBrains Mono','Consolas',monospace;
  white-space:pre;overflow-x:auto;font-size:14px;line-height:1.55;
  color:#22303c;
}
.ds-ascii-cap{
  text-align:center;font-size:13.5px;color:var(--ds-ink-soft);
  margin:-4px 0 16px;font-style:italic;
}

/* ---- tables ------------------------------------------------------------- */
body.ds-page table{
  width:100%;border-collapse:collapse;margin:14px 0;font-size:14.8px;
  background:#fff;
}
body.ds-page th{
  background:var(--ds-primary);color:#fff;padding:9px 11px;
  text-align:center;font-weight:600;
}
body.ds-page td{
  border:1px solid var(--ds-line);padding:8px 11px;text-align:center;
}
body.ds-page td.ds-l{text-align:left;}
body.ds-page tr:nth-child(even) td{background:#f8fafc;}
.ds-hl{background:#fff3cd !important;font-weight:700;}
.ds-ok{background:#e8f8ee !important;}
.ds-sel{background:#ffe8cc !important;font-weight:700;}
.ds-scroll{overflow-x:auto;}

/* ---- two column --------------------------------------------------------- */
.ds-two{display:flex;gap:18px;flex-wrap:wrap;}
.ds-two>div{flex:1 1 320px;min-width:0;}

/* ---- practice ----------------------------------------------------------- */
.ds-practice{
  background:#fff;border:1px solid var(--ds-line);border-radius:10px;
  padding:6px 24px 14px;
}
.ds-practice li{margin-bottom:11px;}
details.ds-sol{
  margin:8px 0 0;background:#f6f9fc;border:1px solid var(--ds-line);
  border-radius:7px;padding:0;
}
details.ds-sol summary{
  cursor:pointer;padding:8px 14px;font-weight:600;font-size:14px;
  color:var(--ds-primary);list-style:none;
}
details.ds-sol summary::-webkit-details-marker{display:none;}
details.ds-sol summary::before{content:'▸ ';}
details.ds-sol[open] summary::before{content:'▾ ';}
details.ds-sol .ds-solbody{padding:2px 16px 12px;font-size:14.8px;}

@media(max-width:680px){
  body.ds-page{font-size:15.5px;padding:0 12px 30px;}
  .ds-hero{padding:22px 20px;}
  .ds-hero h1{font-size:24px;}
  body.ds-page h2{font-size:17.5px;padding:9px 14px;}
  .ds-pager a{flex:1 1 100%;}
  .ds-pager .ds-next{text-align:left;}
}

/* ==========================================================================
   index.html only
   ========================================================================== */
body.ds-home{
  font-family:'Hind Siliguri','Noto Sans Bengali','Segoe UI',sans-serif;
  background:#f6f8fa;color:var(--ds-ink);margin:0;padding:0 20px 50px;
  line-height:1.75;
}
.ds-home-hero{
  max-width:1120px;margin:0 auto 30px;
  background:linear-gradient(135deg,#101b26 0%,#1a5276 55%,#117864 130%);
  color:#fff;border-radius:16px;padding:40px 38px;
}
.ds-home-hero h1{margin:0 0 12px;font-size:38px;line-height:1.25;}
.ds-home-hero p{margin:0;color:#c6dae8;font-size:16.5px;max-width:64ch;}
.ds-stats{display:flex;gap:26px;flex-wrap:wrap;margin-top:26px;}
.ds-stat b{display:block;font-size:27px;line-height:1.2;color:#7fe0c4;}
.ds-stat span{font-size:12.5px;color:#9fb6c7;letter-spacing:.6px;}

.ds-sec{max-width:1120px;margin:0 auto 34px;}
.ds-sec-head{
  display:flex;align-items:baseline;gap:12px;margin:0 0 4px;
  padding-bottom:9px;border-bottom:2px solid var(--ds-line);
}
.ds-sec-head h2{margin:0;font-size:21px;color:var(--ds-primary);}
.ds-sec-head span{font-size:13.5px;color:var(--ds-ink-soft);}

.ds-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:16px;margin-top:18px;}
.ds-card{
  background:#fff;border:1px solid var(--ds-line);border-radius:12px;
  padding:18px 20px 16px;text-decoration:none;color:var(--ds-ink);
  display:flex;flex-direction:column;gap:8px;position:relative;
  transition:transform .15s,box-shadow .15s,border-color .15s;
}
.ds-card:hover{
  transform:translateY(-2px);border-color:var(--ds-primary);
  box-shadow:0 14px 30px -20px rgba(26,82,118,.85);
}
.ds-card-num{
  font-family:'JetBrains Mono',monospace;font-size:11.5px;
  color:var(--ds-ink-soft);letter-spacing:1px;
}
.ds-card h3{margin:0;font-size:17.5px;font-weight:600;line-height:1.4;}
.ds-card p{margin:0;font-size:14px;color:var(--ds-ink-soft);line-height:1.6;}
.ds-card-foot{
  margin-top:auto;padding-top:10px;display:flex;gap:8px;align-items:center;
  flex-wrap:wrap;font-size:12px;
}
.ds-pill{
  padding:3px 10px;border-radius:12px;font-weight:600;
  background:#eef2f6;color:#44566a;
}
.ds-pill.ds-p-hot{background:#fdecec;color:#a52a2a;}
.ds-pill.ds-p-mid{background:#fff5e5;color:#8a5a00;}
.ds-pill.ds-p-low{background:#eef7f2;color:#26694a;}
.ds-pill.ds-p-new{background:#e07a3f;color:#fff;}
.ds-stars{color:#e0a020;letter-spacing:1px;font-size:13px;}

.ds-check{
  position:absolute;top:14px;right:14px;width:22px;height:22px;
  border:2px solid var(--ds-line);border-radius:6px;background:#fff;
  cursor:pointer;display:flex;align-items:center;justify-content:center;
  font-size:13px;color:transparent;transition:all .15s;
}
.ds-check:hover{border-color:var(--ds-accent);}
.ds-check.ds-done{background:var(--ds-accent);border-color:var(--ds-accent);color:#fff;}

.ds-plan{
  background:#fff;border:1px solid var(--ds-line);border-radius:12px;
  padding:4px 0;overflow:hidden;
}
.ds-plan table{width:100%;border-collapse:collapse;font-size:14.5px;}
.ds-plan th{background:var(--ds-bar);color:#fff;padding:10px 13px;text-align:left;font-weight:600;}
.ds-plan td{border-top:1px solid var(--ds-line);padding:9px 13px;}
.ds-plan td:first-child{font-family:'JetBrains Mono',monospace;color:var(--ds-ink-soft);width:52px;}
.ds-plan a{color:var(--ds-primary);text-decoration:none;font-weight:600;}
.ds-plan a:hover{text-decoration:underline;}
.ds-plan tr:hover td{background:#f8fafc;}

.ds-note{
  max-width:1120px;margin:0 auto 34px;background:var(--ds-gold-lt);
  border-left:5px solid #d4ac0d;border-radius:8px;padding:16px 22px;
}
.ds-note b{color:var(--ds-gold);}

@media(max-width:680px){
  .ds-home-hero{padding:28px 22px;}
  .ds-home-hero h1{font-size:27px;}
  .ds-plan td:first-child{width:38px;}
}

/* ==========================================================================
   Mobile safety net — applies to every page, including the four original
   ones, so nothing pushes the document wider than the phone screen.
   Wide tables and monospace blocks scroll inside themselves instead.
   ========================================================================== */
.ds-ans small{max-width:100%;overflow-x:auto;}

@media(max-width:760px){
  html,body{overflow-x:hidden;}
  table{display:block;width:auto;max-width:100%;overflow-x:auto;}
  pre,.ds-ascii{max-width:100%;overflow-x:auto;}
  code{overflow-wrap:anywhere;}
  /* grid/flex children default to min-width:auto, which lets long content
     blow past the viewport — let them shrink instead */
  [class*="grid"] > *,[class*="Grid"] > *,
  [class*="card"],[class*="col"],[class*="two"] > *{min-width:0;}
  img,svg{max-width:100%;height:auto;}
}