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

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
  color: #eee;
  min-height: 100vh;
}

/* ===================================
           THEORY SECTION (top of page)
           =================================== */
.theory {
  background-color: #0a0a1a;
  padding: 25px;
  margin: 20px;
  border-radius: 16px;
}

.theory h2 {
  color: #4a90e2;
  margin-bottom: 15px;
}

.theory h3 {
  color: #e94560;
  margin: 20px 0 10px;
}

.theory p {
  color: #ccc;
  line-height: 1.6;
  margin-bottom: 15px;
}

.theory ul {
  margin-left: 25px;
  color: #ccc;
  line-height: 1.8;
}

.theory code {
  background-color: #1a1a2e;
  padding: 2px 6px;
  border-radius: 4px;
  color: #82b1ff;
}

/* ===================================
           NAVBAR (mobile-first)
           =================================== */
.navbar {
  background-color: #0f3460;
  padding: 15px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: relative;
}

.logo {
  font-size: 24px;
  font-weight: bold;
  color: #4a90e2;
  text-decoration: none;
}

/* ===================================
           HAMBURGER BUTTON (label)
           =================================== */
.hamburger {
  font-size: 28px;
  cursor: pointer;
  user-select: none;
}

/* ===================================
           HIDDEN CHECKBOX
           =================================== */
#menu-toggle {
  display: none;
}

/* ===================================
           MENU (hidden by default on mobile)
           =================================== */
.nav-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background-color: #0f3460;
  flex-direction: column;
  list-style: none;
  padding: 20px;
  gap: 15px;
  border-top: 1px solid #1a1a2e;
}

.nav-menu li a {
  color: white;
  text-decoration: none;
  font-size: 18px;
  display: block;
  padding: 12px;
  transition: all 0.3s ease;
}

.nav-menu li a:hover {
  background-color: #4a90e2;
  border-radius: 8px;
  padding-left: 20px;
}

/* ===================================
           SHOW MENU WHEN CHECKBOX IS CHECKED
           =================================== */
#menu-toggle:checked ~ .nav-menu {
  display: flex;
}

/* ===================================
           CONTENT SECTION
           =================================== */
.content {
  padding: 40px 20px;
  max-width: 800px;
  margin: 0 auto;
}

.content h1 {
  font-size: 28px;
  margin-bottom: 20px;
}

.content p {
  line-height: 1.6;
  color: #ccc;
  margin-bottom: 20px;
}

/* ===================================
           DESKTOP LAYOUT (min-width: 768px)
           =================================== */
@media (min-width: 768px) {
  .hamburger {
    display: none;
  }

  .nav-menu {
    display: flex;
    position: static;
    flex-direction: row;
    padding: 0;
    gap: 30px;
    border-top: none;
  }

  .nav-menu li a {
    padding: 0;
    font-size: 16px;
  }

  .nav-menu li a:hover {
    background-color: transparent;
    color: #4a90e2;
    padding-left: 0;
  }
}

/* ===================================
           CODE DISPLAY
           =================================== */
.code-block {
  background-color: #0a0a1a;
  padding: 20px;
  border-radius: 12px;
  font-family: "Courier New", monospace;
  font-size: 13px;
  color: #82b1ff;
  overflow-x: auto;
  margin: 20px;
}

.demo-container {
  background-color: #0f3460;
  border-radius: 16px;
  margin: 20px;
  overflow: hidden;
}

footer {
  text-align: center;
  padding: 30px;
  color: #666;
  font-size: 14px;
}