@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap');

:root {
  --bg-sidebar: #111827;
  --text-light: #f3f4f6;
  --accent: #2563EB;
  --bg-card: #ffffff;
  --shadow: rgba(0, 0, 0, 0.1);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: 'Inter', sans-serif;
  background: #F9FAFB;
  color: #1F2937;
  overflow-x: hidden;
}

/* Sidebar */
#sidebar {
  position: fixed;
  top: 0; bottom: 0; left: 0;
  width: 260px;
  background: var(--bg-sidebar);
  color: var(--text-light);
  display: flex; flex-direction: column;
  transition: transform .3s ease;
  transform: translateX(-100%);
  z-index: 1000;
}
#sidebar.active { transform: translateX(0); }
#sidebar .logo {
  font-size: 1.5rem; font-weight: 700;
  padding: 1.5rem; text-align: center;
  border-bottom: 1px solid #374151;
}
#chapters-menu { overflow-y: auto; }

/* Capitole */
.chapter { border-bottom: 1px solid #374151; }
.chapter > .title {
  padding: 1rem; cursor: pointer; font-weight: 600;
  display: flex; justify-content: space-between;
}
.chapter > .title:hover { background: #1F2937; }
.submenu {
  display: none; flex-direction: column;
  background: #111827;
}
.submenu a {
  padding: .75rem 1.5rem;
  text-decoration: none;
  color: #D1D5DB;
  font-size: .95rem;
  transition: background .2s;
}
.submenu a:hover { background: #1F2937; }

/* Toggle button */
.menu-toggle {
  position: fixed; top: 1.25rem; left: 1.25rem;
  background: var(--accent); color: white;
  border: none; padding: .5rem .75rem;
  border-radius: .375rem; font-size: 1.25rem;
  cursor: pointer; z-index: 1100;
  box-shadow: 0 2px 8px var(--shadow);
}

/* Wrapper & Header */
#wrapper {
  transition: margin-left .3s ease;
  margin-left: 0;
  padding-top: 4rem;
}
#wrapper.shift { margin-left: 260px; }
header {
  position: sticky; top: 0; background: white;
  padding: 1rem 2rem; border-bottom: 1px solid #E5E7EB;
  box-shadow: 0 1px 4px var(--shadow);
  z-index: 900;
}
header h1 { font-size: 1.75rem; }
.home-btn {
  margin-left: 1rem; background: var(--accent);
  color: white; border: none; padding: .5rem 1rem;
  border-radius: .375rem; font-size: .95rem;
  cursor: pointer; transition: background .2s;
}
.home-btn:hover { background: #1E40AF; }

/* Content */
main#content {
  max-width: 900px; margin: 2rem auto; padding: 0 1rem;
  line-height: 1.7; font-size: 1.1rem;
}
main#content img {
  max-width: 100%; display: block;
  margin: 1.5rem auto;
  border-radius: .375rem;
  box-shadow: 0 2px 6px var(--shadow);
}

/* Cards pentru secțiuni teorie */
.theory-section {
  background: var(--bg-card);
  padding: 1.5rem; margin-bottom: 2rem;
  border-radius: .5rem;
  box-shadow: 0 1px 4px var(--shadow);
}