:root {
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --code-bg: #f1f5f9;
  --quote-bg: #eff6ff;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 48px 20px;
  background: linear-gradient(to bottom, #f8fafc, #eef2f7);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.75;
}

#content {
  max-width: 860px;
  margin: 0 auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 56px;
  box-shadow: var(--shadow);
}

/* Typography */

h1, h2, h3, h4, h5, h6 {
  margin-top: 2em;
  margin-bottom: 0.6em;
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: -0.02em;
  scroll-margin-top: 24px;
}

h1 {
  font-size: 2.5rem;
  margin-top: 0;
  padding-bottom: 0.4em;
  border-bottom: 1px solid var(--border);
}

h2 {
  font-size: 2rem;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--border);
}

h3 {
  font-size: 1.4rem;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--border);
}

h4 {
  font-size: 1.2rem;
}

p {
  margin: 1em 0;
}

strong {
  font-weight: 700;
}

em {
  color: #334155;
}

/* Links */

a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

a:hover {
  color: var(--accent-hover);
  text-decoration: underline;
}

/* Lists */

ul, ol {
  padding-left: 1.4rem;
  margin: 1rem 0;
}

li + li {
  margin-top: 0.45rem;
}

/* Code */

code {
  font-family: "SFMono-Regular", Consolas, Monaco, monospace;
  background: var(--code-bg);
  padding: 0.18em 0.45em;
  border-radius: 6px;
  font-size: 0.92em;
}

pre {
  background: #0f172a;
  color: #e2e8f0;
  padding: 18px 20px;
  border-radius: 14px;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: 0.95rem;
  line-height: 1.6;
}

pre code {
  background: transparent;
  padding: 0;
  color: inherit;
}

/* Quotes */

blockquote {
  margin: 1.5rem 0;
  padding: 0.9rem 1.2rem;
  border-left: 4px solid var(--accent);
  background: var(--quote-bg);
  color: #1e3a8a;
  border-radius: 10px;
}

/* Tables */

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  overflow: hidden;
  border-radius: 12px;
  border: 1px solid var(--border);
}

th, td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: #f8fafc;
  font-weight: 700;
}

tr:last-child td {
  border-bottom: none;
}

/* Horizontal rule */

hr {
  border: none;
  height: 1px;
  background: var(--border);
  margin: 2.5rem 0;
}

/* Images */

img {
  max-width: 100%;
  border-radius: 4px;
  margin: 1rem 0;
}

/* Scrollbars */

::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 999px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

/* Mobile */

@media (max-width: 768px) {
  body {
    padding: 20px 12px;
    font-size: 16px;
  }

  #content {
    padding: 28px 20px;
    border-radius: 16px;
  }

  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1.6rem;
  }

  h3 {
    font-size: 1.3rem;
  }
}
.floating-btn {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%) translateY(12px);

  min-width: 160px;
  height: 52px;
  padding: 0 10px;

  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;

  border: none;
  border-radius: 100px;
  font-size: 16px;
  font-weight: 400;
  white-space: nowrap;
  cursor: pointer;

  background: #487ef3;
  color: white;
  box-shadow: 0 10px 24px rgba(0,0,0,.18);

  opacity: 0;
  pointer-events: none;
  transition: all .25s ease;
  z-index: 999;

  &.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
    pointer-events: auto;
  }
}