:root {
  --sidebar-width: 260px;
  --text: #202124;
  --muted: #5f6368;
  --rule: #d9d9d9;
  --link: #0645ad;
  --bg: #ffffff;
  --sidebar-bg: #f7f7f7;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 17px;
  line-height: 1.6;
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  padding: 1.5rem 1.25rem;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--rule);
  overflow-y: auto;
}

.sidebar-title {
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 1.25rem;
}

.sidebar nav a {
  display: block;
  padding: 0.45rem 0;
  color: var(--text);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.sidebar nav a:hover,
.sidebar nav a:focus {
  color: var(--link);
  border-bottom-color: var(--link);
}

.content {
  max-width: 900px;
  margin-left: var(--sidebar-width);
  padding: 2rem 3rem 4rem;
}

h1, h2, h3 {
  line-height: 1.25;
  font-weight: 700;
}

h1 {
  font-size: 2rem;
  text-align: center;
  margin-top: 0;
}

h2 {
  font-size: 1.35rem;
  margin-top: 2.5rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--rule);
}

h3 {
  font-size: 1.1rem;
  margin-top: 1.5rem;
}

a { color: var(--link); }
hr { border: 0; border-top: 1px solid var(--rule); margin: 2rem 0; }
.profile {
  float: left;
  width: 120px;
  margin: 0 1.2rem 0.5rem 0;
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
}
.profile img { width: 100px; height: auto; display: block; margin: 0 auto 0.25rem; }
.footer { text-align: center; margin-top: 2rem; font-size: 0.95rem; color: var(--muted); }
.menu-toggle { display: none; }

@media (max-width: 760px) {
  .menu-toggle {
    display: block;
    position: fixed;
    top: 0.75rem;
    left: 0.75rem;
    z-index: 20;
    padding: 0.45rem 0.65rem;
  }
  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.2s ease;
    z-index: 10;
  }
  body.nav-open .sidebar { transform: translateX(0); }
  .content {
    margin-left: 0;
    padding: 4rem 1.25rem 3rem;
  }
  .profile { float: none; margin: 0 auto 1rem; }
}