/* ── ROOT ── */
  :root {
    /* 🎯 YOUR COLORS */
    --accent: #ffa500;
    --accent-light: #fff3cd;
    --accent-dark: #cc8400;
    --surface: #ffffff;
    --surface2: #f8f9fa;
    --border: #dee2e6;
    --text: #212529;
    --muted: #6c757d;
    --green: #198754;
    --green-bg: #d1e7dd;
    --green-border: #a3cfbb;
    --radius: 0.5rem;
    --mono: SFMono-Regular, Menlo, Monaco, Consolas, "Courier New", monospace;

    /* 🔄 MAP TO EXISTING SYSTEM (IMPORTANT) */
    --bg: #ffffff;
    --bg2: #f8f9fa;
    --bg3: #ffffff;

    --border2: #dee2e6;

    --text2: #495057;
    --text3: #6c757d;

    --accent2: #ffc107;
    --accent-glow: rgba(255, 165, 0, 0.15);

    --blue: #0d6efd;
    --orange: #ffa500;

    --sidebar-w: 300px;
    --banner-h: 130px;
  }

  *,
  *::before,
  *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }

  /* ── FULL SHELL ── */
  .rc-shell {
    display: flex;
    flex-direction: column;
    font-family: var(--sans);
    background: var(--bg);
    color: var(--text);
  }

  /* ── BANNER (static, always visible) ── */
  .rc-banner {
    flex-shrink: 0;
    background: linear-gradient(100deg, #ffffff 0%, #f8f9fa 100%);
    border-bottom: 1px solid var(--border2);
    padding: 20px 28px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    position: relative;
    overflow: hidden;
  }
  .rc-banner::before {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(
      ellipse 60% 100% at 80% 50%,
      rgba(249, 115, 22, 0.06),
      transparent
    );
    pointer-events: none;
  }
  .rc-banner::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent), transparent);
    opacity: 0.5;
  }

  .rc-banner-left {
    display: flex;
    align-items: center;
    gap: 16px;
    z-index: 1;
  }

  .rc-banner-icon {
    width: 52px;
    height: 52px;
    background: linear-gradient(135deg, var(--accent), var(--accent2));
    border-radius: 12px;
    display: grid;
    place-items: center;
    font-size: 1.4rem;
    box-shadow: 0 4px 20px rgba(249, 115, 22, 0.35);
    flex-shrink: 0;
  }

  .rc-banner-title {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--text);
    line-height: 1.2;
  }

  .rc-banner-title span {
    color: var(--accent);
  }

  .rc-banner-sub {
    font-size: 0.78rem;
    color: var(--text2);
    margin-top: 3px;
    font-family: var(--mono);
  }

  .rc-banner-stats {
    display: flex;
    gap: 12px;
    z-index: 1;
  }

  .rc-stat {
    text-align: center;
    background: var(--bg3);
    border: 1px solid var(--border2);
    border-radius: var(--radius);
    padding: 8px 16px;
  }

  .rc-stat-num {
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--accent);
    font-family: var(--mono);
    line-height: 1;
  }

  .rc-stat-lbl {
    font-size: 0.65rem;
    color: var(--text3);
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-top: 2px;
  }

  /* ── BODY (sidebar + content) ── */
  .rc-body {
    display: flex;
    overflow: hidden;
    /* height set dynamically by JS after banner renders */
    height: calc(100vh - 64px - var(--banner-actual, 92px) - 60px);
    /*changes made*/
    min-height: 500px;
  }

  /* ── SIDEBAR ── */
  .rc-sidebar {
    width: var(--sidebar-w);
    flex-shrink: 0;
    background: var(--surface2);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition:
      transform 0.3s ease,
      width 0.3s ease;
  }

  .rc-sidebar-head {
    padding: 14px 14px 12px;
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
  }

  .rc-search-wrap {
    position: relative;
  }

  .rc-search-wrap i {
    position: absolute;
    left: 11px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text3);
    font-size: 0.8rem;
    pointer-events: none;
  }

  .rc-search {
    width: 100%;
    background: var(--bg3);
    border: 1px solid var(--border2);
    border-radius: var(--radius);
    padding: 9px 12px 9px 34px;
    font-size: 0.82rem;
    color: var(--text);
    outline: none;
    font-family: var(--sans);
    transition:
      border-color 0.2s,
      box-shadow 0.2s;
  }

  .rc-search:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
  }

  .rc-search::placeholder {
    color: var(--text3);
  }

  .rc-sidebar-count {
    font-size: 0.68rem;
    color: var(--text3);
    font-family: var(--mono);
    padding: 7px 14px 0;
  }

  .rc-problems {
    flex: 1;
    overflow-y: auto;
    padding: 6px 8px 20px;
  }

  .rc-problems::-webkit-scrollbar {
    width: 4px;
  }

  .rc-problems::-webkit-scrollbar-track {
    background: transparent;
  }

  .rc-problems::-webkit-scrollbar-thumb {
    background: var(--border2);
    border-radius: 4px;
  }

  .rc-prob-item {
    display: flex;
    align-items: center;
    gap: 9px;
    padding: 9px 10px;
    border-radius: 7px;
    cursor: pointer;
    transition: background 0.15s;
    border: 1px solid transparent;
  }

  .rc-prob-item:hover {
    background: var(--bg3);
  }

  .rc-prob-item.active {
    background: rgba(249, 115, 22, 0.08);
    border-color: rgba(249, 115, 22, 0.25);
  }

  .rc-prob-item.active .rc-prob-title {
    color: var(--accent);
  }

  .rc-prob-num {
    font-family: var(--mono);
    font-size: 0.65rem;
    color: var(--text3);
    min-width: 30px;
    flex-shrink: 0;
  }

  .rc-prob-title {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text);
    line-height: 1.3;
    flex: 1;
    transition: color 0.15s;
  }

  .rc-prob-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    flex-shrink: 0;
    background: var(--green);
    opacity: 0;
    transition: opacity 0.15s;
  }

  .rc-prob-item.active .rc-prob-dot {
    opacity: 1;
  }

  /* ── CONTENT AREA ── */
  .rc-content {
    flex: 1;
    overflow-y: auto;
    background: var(--bg);
    min-width: 0;
    height: 100%;
  }

  .rc-content::-webkit-scrollbar {
    width: 5px;
  }

  .rc-content::-webkit-scrollbar-track {
    background: transparent;
  }

  .rc-content::-webkit-scrollbar-thumb {
    background: var(--border2);
    border-radius: 4px;
  }

  .rc-article {
    max-width: 820px;
    margin: 0 auto;
    padding: 32px 32px 160px;
    /* extra bottom padding so nav never clips */
  }

  /* ── PROBLEM HEADER ── */
  .rc-art-head {
    margin-bottom: 24px;
  }

  .rc-art-eyebrow {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px;
  }

  .rc-art-id {
    font-family: var(--mono);
    font-size: 0.7rem;
    color: var(--text3);
    background: var(--bg3);
    padding: 3px 10px;
    border-radius: 4px;
    border: 1px solid var(--border2);
  }

  .rc-art-badge {
    font-size: 0.65rem;
    font-weight: 700;
    font-family: var(--mono);
    padding: 3px 10px;
    border-radius: 4px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
  }

  .badge-basic {
    background: rgba(34, 197, 94, 0.12);
    color: #22c55e;
    border: 1px solid rgba(34, 197, 94, 0.25);
  }

  .badge-moderate {
    background: rgba(251, 191, 36, 0.12);
    color: #fbbf24;
    border: 1px solid rgba(251, 191, 36, 0.25);
  }

  .badge-advanced {
    background: rgba(239, 68, 68, 0.12);
    color: #ef4444;
    border: 1px solid rgba(239, 68, 68, 0.25);
  }

  .rc-art-title {
    font-size: 1.85rem;
    font-weight: 800;
    color: var(--text);
    line-height: 1.2;
    letter-spacing: -0.5px;
  }

  .rc-art-desc {
    background: var(--bg2);
    border: 1px solid var(--border2);
    border-left: 3px solid var(--accent);
    border-radius: 0 var(--radius) var(--radius) 0;
    padding: 14px 18px;
    font-size: 0.9rem;
    color: var(--text2);
    line-height: 1.75;
    margin-bottom: 24px;
  }

  .rc-desc-label {
    font-family: var(--mono);
    font-size: 0.90rem;
    font-weight: 700;
    color: var(--accent); /* matches description border */
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 6px;
  }

  .rc-desc-label::before {
    content: "";
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--accent); /* same accent color */
    flex-shrink: 0;
  }
    .rc-desc-img {
  margin-top: 20px;
  text-align: center;
}

.rc-desc-img img {
  width: 100%;
  max-width: 500px;
  border-radius: 12px;
  border: 1px solid var(--border2);
}

  /* ── EXPLANATION ── */
  .rc-explanation {
    background: var(--bg2);
    border: 1px solid var(--border2);
    border-left: 3px solid var(--blue);
    border-radius: 0 var(--radius) var(--radius) 0;
    padding: 14px 18px;
    margin: 20px 0px;
    font-size: 0.88rem;
    color: var(--text2);
    line-height: 1.75;
    margin-bottom: 24px;
  }

  .rc-explanation-label {
    font-family: var(--mono);
    font-size: 0.90rem;
    font-weight: 700;
    color: var(--blue);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 6px;
  }

  .rc-explanation-label::before {
    content: "";
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--blue);
    flex-shrink: 0;
  }
.rc-complexity {
  display: flex;
  flex-direction: column;   /* stack vertically */
  align-items: flex-start;  /* ❗ keeps box small (not full width) */
  gap: 12px;
  margin: 20px 0;
}

.rc-complexity-box {
  background: var(--bg2);
  border: 1px solid var(--border2);
  border-radius: 10px;

  width: 140px;              /* ✅ fixed compact width */
  padding: 10px 12px;

  display: flex;
  flex-direction: column;
  gap: 4px;

  font-family: var(--mono);
}



.rc-complexity-box span {
  font-size: 0.7rem;
  color: var(--text3);
  font-weight: 600;
}

.rc-complexity-box strong {
  font-size: 0.9rem;
  color: var(--accent);
  font-weight: 700;
}
.rc-art-meta {
  margin: 6px 0 14px;

  font-size: 15px;              /* ✅ bigger like screenshot */
  font-family: 'Sora', sans-serif;

  color: #111827;               /* ✅ dark (almost black) */
  font-weight: 500;             /* ✅ medium bold (perfect match) */

  letter-spacing: 0.2px;
}

/* keep normal text normal */
.rc-art-meta span {
  font-weight: 400;
}

/* ONLY name bold */
.rc-name {
  font-weight: 600;
  color: #111827;
}
/* DATE */
.rc-art-meta span:first-child {
  color: #6b7280;
  font-weight: 400;
}

/* AUTHOR */
.rc-art-meta span:last-child {
  color: #111827;   /* ✅ darker */
  font-weight: 600; /* ✅ bold */
}
  /* ── CODE BLOCK (GFG-style) ── */
  .rc-code-block {
    background: var(--bg2);
    border: 1px solid var(--border2);
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 24px;
  }

  .rc-lang-tabs {
    display: flex;
    gap: 2px;
    padding: 10px 12px 0;
    background: #0b0d13;
    border-bottom: 1px solid var(--border);

    overflow-x: auto;
    overflow-y: hidden;
    white-space: nowrap;
    -webkit-overflow-scrolling: touch;
    flex: 0 0 auto; 
  }

  .rc-lang-tabs::-webkit-scrollbar {
    display: none;
  }
  .rc-lang-tabs {
    scrollbar-width: none; /* Firefox */
  }
  .rc-lang-tab {
    padding: 7px 16px;
    border-radius: 7px 7px 0 0;
    border: none;
    cursor: pointer;
    font-family: var(--mono);
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    background: transparent;
    color: var(--text3);
    border: 1px solid transparent;
    border-bottom: none;
    transition: all 0.15s;
  }
  .rc-lang-tab:hover {
    color: var(--text2);
    background: var(--bg3);
  }
  .rc-lang-tab.active {
    background: #1e1e2e;
    color: var(--accent);
    border-color: var(--border2);
    border-bottom-color: #1e1e2e;
  }

  .rc-code-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: #1e1e2e;
    padding: 8px 14px;
  }

  .rc-code-file {
    font-family: var(--mono);
    font-size: 0.7rem;
    color: var(--text3);
    display: flex;
    align-items: center;
    gap: 7px;
  }

  .rc-code-file i {
    color: var(--accent);
  }

  .rc-copy-btn {
    background: none;
    border: 1px solid var(--border2);
    border-radius: 5px;
    color: var(--text3);
    padding: 4px 12px;
    font-size: 0.72rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: all 0.15s;
    font-family: var(--mono);
  }

  .rc-copy-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
  }

  .rc-copy-btn.ok {
    border-color: var(--green);
    color: var(--green);
  }

  .rc-code-pane {
    display: none;
  }

  .rc-code-pane.active {
    display: block;
  }

  pre[class*="language-"] {
    margin: 0 !important;
    border-radius: 0 !important;
    background: #1e1e2e !important;
    padding: 18px !important;
    font-size: 0.83rem !important;
    max-height: 380px;
    overflow: auto;
    font-family: var(--mono) !important;
    line-height: 1.7 !important;
  }

  pre[class*="language-"]::-webkit-scrollbar {
    width: 4px;
    height: 4px;
  }

  pre[class*="language-"]::-webkit-scrollbar-thumb {
    background: var(--border2);
    border-radius: 4px;
  }

  /* ── OUTPUT ── */
  .rc-output {
    margin: 20px 0px;
    background: var(--bg2);
    border: 1px solid var(--green-border);
    border-radius: 10px;
    padding: 14px 16px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
  }
  .rc-output-label {
    font-family: var(--mono);
    font-size: 0.90rem;
    font-weight: 700;
    color: var(--green);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 6px;
  }
  .rc-output-label::before {
    content: "";
    width: 6px;
    height: 6px;
    background: var(--green);
    border-radius: 50%;
    box-shadow: 0 0 6px var(--green);
    animation: pulse-green 2s infinite;
  }
  @keyframes pulse-green {
    0%,
    100% {
      opacity: 1;
    }
    50% {
      opacity: 0.4;
    }
  }
  .rc-output-txt {
    font-family: var(--mono);
    font-size: 0.8rem;
    color: #000000;
    white-space: pre-wrap;
    line-height: 1.65;
  }

  /* ── NAV ARROWS ── */
  .rc-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid var(--border);
  }

  .rc-nav-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--bg2);
    border: 1px solid var(--border2);
    border-radius: var(--radius);
    color: var(--text2);
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 600;
    font-family: var(--sans);
    transition: all 0.18s;
  }

  .rc-nav-btn:hover:not(:disabled) {
    border-color: var(--accent);
    color: var(--accent);
    background: rgba(249, 115, 22, 0.06);
  }

  .rc-nav-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
  }

  .rc-nav-btn i {
    font-size: 0.8rem;
  }

  .rc-nav-info {
    font-family: var(--mono);
    font-size: 0.72rem;
    color: var(--text3);
  }

  /* ── WELCOME STATE ── */
  .rc-welcome {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    text-align: center;
    padding: 40px;
  }

  .rc-welcome-icon {
    font-size: 3rem;
    margin-bottom: 20px;
    background: linear-gradient(135deg, var(--accent), var(--accent2));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
  }

  .rc-welcome h2 {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--text);
    margin-bottom: 10px;
  }

  .rc-welcome p {
    color: var(--text2);
    font-size: 0.9rem;
    max-width: 340px;
    line-height: 1.7;
  }

  /* ── MOBILE TOGGLE ── */
  .rc-sidebar-toggle {
    display: none;
    position: fixed;
    bottom: 24px;
    left: 24px;
    z-index: 200;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--accent);
    border: none;
    color: #fff;
    font-size: 1rem;
    cursor: pointer;
    box-shadow: 0 4px 20px rgba(249, 115, 22, 0.5);
    align-items: center;
    justify-content: center;
    transition: transform 0.2s;
  }

  .rc-sidebar-toggle:active {
    transform: scale(0.92);
  }

  .rc-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    z-index: 150;
    backdrop-filter: blur(2px);
  }

  /* ── NO RESULTS ── */
  .rc-no-results {
    text-align: center;
    padding: 40px 20px;
    color: var(--text3);
    font-size: 0.85rem;
  }

  .rc-no-results i {
    font-size: 1.6rem;
    display: block;
    margin-bottom: 10px;
    color: var(--border2);
  }

  /* ── RESPONSIVE ── */
  @media (max-width: 768px) {
    :root {
      --sidebar-w: 280px;
    }
    .rc-banner-stats {
      display: none;
    }
    .rc-banner-title {
      font-size: 1rem;
    }
    .rc-body {
      height: calc(100vh - 64px - var(--banner-actual, 80px));
    }
    .rc-sidebar {
      position: fixed;
      top: 0;
      left: 0;
      bottom: 0;
      z-index: 160;
      transform: translateX(-100%);
      padding-top: 64px;
    }
    .rc-sidebar.open {
      transform: translateX(0);
    }
    .rc-sidebar-toggle {
      display: flex;
    }
    .rc-overlay.open {
      display: block;
    }
    .rc-article {
      padding: 20px 16px 120px;
    }
    .rc-art-title {
      font-size: 1.4rem;
    }
/* ── EXPLANATION BODY ── */
.rc-explanation-body {
  font-size: 0.875rem;
  color: var(--text2);
  line-height: 1.75;
}

/* Main title: "Understanding the Code Step by Step" */
.rc-exp-main-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--accent);
  display: inline-block;
}

/* Numbered section header: "1. Node Structure" */
.rc-exp-section-header {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--blue);
  font-family: var(--mono);
  margin: 14px 0 6px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.rc-exp-section-header::before {
  content: '';
  display: inline-block;
  width: 3px;
  height: 1em;
  background: var(--blue);
  border-radius: 2px;
  flex-shrink: 0;
}

/* Label ending in colon: "Each node contains:", "Steps:" */
.rc-exp-label {
  font-weight: 600;
  color: var(--text);
  font-size: 0.84rem;
  margin: 8px 0 4px;
}

/* "Why O(1)?" questions */
.rc-exp-why {
  font-weight: 600;
  color: var(--accent);
  font-size: 0.83rem;
  font-family: var(--mono);
  margin: 6px 0 2px;
}

/* Short bold labels: "Execution Flow", "Key Concept", "Summary" */
.rc-exp-bold-label {
  font-weight: 700;
  color: var(--text);
  font-size: 0.87rem;
  margin: 10px 0 4px;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--muted);
}

/* Bullet lines */
.rc-exp-bullet {
  display: flex;
  align-items: baseline;
  gap: 6px;
  margin: 3px 0;
  padding-left: 4px;
}
.rc-exp-bullet-dot {
  color: var(--blue);
  font-size: 0.8rem;
  flex-shrink: 0;
  line-height: 1;
}
.rc-exp-bullet-key {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 600;
}
.rc-exp-bullet-arrow {
  color: var(--muted);
  font-size: 0.8rem;
}
.rc-exp-bullet-val {
  color: var(--text2);
  font-size: 0.84rem;
}
.rc-exp-bullet-text {
  color: var(--text2);
  font-size: 0.84rem;
}

/* Flow lines: "insert_tail(1) → 1" */
.rc-exp-flow-line {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: #86efac;
  background: rgba(34, 197, 94, 0.07);
  border-left: 2px solid rgba(34, 197, 94, 0.4);
  padding: 4px 10px;
  border-radius: 0 4px 4px 0;
  margin: 3px 0;
}

/* "[data | next] → NULL" representation */
.rc-exp-representation {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: #c4b5fd;
  background: rgba(139, 92, 246, 0.07);
  border-left: 2px solid rgba(139, 92, 246, 0.35);
  padding: 4px 10px;
  border-radius: 0 4px 4px 0;
  margin: 4px 0;
}

/* Regular body text */
.rc-exp-body {
  color: var(--text2);
  font-size: 0.87rem;
  margin: 2px 0;
}

/* Spacing gap */
.rc-exp-gap {
  height: 5px;
}

/* Horizontal rule */
.rc-exp-divider {
  border: none;
  border-top: 1px solid var(--border2);
  margin: 12px 0;
  opacity: 0.4;
}