* {
  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;
  padding: 20px;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

h1 {
  font-size: clamp(1.75rem, 2rem + 2vw, 2.5rem);
  text-align: center;
  margin-bottom: 0.5rem;
}

.subtitle {
  text-align: center;
  color: #aaa;
  margin-bottom: 2rem;
}

/* ===================================
           THEORY SECTION
           =================================== */
.theory {
  background-color: #0a0a1a;
  border-radius: 1rem;
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.theory h2 {
  color: #4a90e2;
  margin-bottom: 1rem;
  font-size: clamp(1.25rem, 1.25rem + 0.5vw, 1.5rem);
}

.theory h3 {
  color: #e94560;
  margin: 1.5rem 0 0.75rem;
}

.theory p {
  color: #ccc;
  line-height: 1.6;
  margin-bottom: 1rem;
}

.theory ul {
  margin-left: 1.5rem;
  color: #ccc;
  line-height: 1.8;
}

.theory code {
  background-color: #1a1a2e;
  padding: 0.125rem 0.375rem;
  border-radius: 0.25rem;
  color: #82b1ff;
}

/* ===================================
           CONTAINER QUERY SETUP
           =================================== */
/* Step 1: Define which elements are containers */
.card-container {
  container-type: inline-size;
  container-name: card-container;
  background-color: #0f3460;
  border-radius: 1rem;
  padding: 1rem;
  margin-bottom: 1rem;
}

/* Step 2: Create the component that will respond */
.card {
  background-color: #1a1a2e;
  border-radius: 0.75rem;
  overflow: hidden;
  transition: transform 0.3s ease;
}

.card:hover {
  transform: translateY(-4px);
}

.card-img {
  background: linear-gradient(135deg, #4a90e2, #e94560);
  min-height: 120px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
}

.card-content {
  padding: 1rem;
}

.card-title {
  font-size: 1.125rem;
  font-weight: bold;
  margin-bottom: 0.5rem;
}

.card-description {
  font-size: 0.875rem;
  color: #aaa;
}

/* ===================================
           STEP 3: Container Query!
           When container is WIDE (>= 400px),
           make card horizontal (row)
           =================================== */
@container card-container (min-width: 400px) {
  .card {
    display: flex;
  }

  .card-img {
    min-width: 150px;
    min-height: 150px;
  }

  .card-content {
    flex: 1;
  }
}

/* When container is even WIDER (>= 600px) */
@container card-container (min-width: 600px) {
  .card-img {
    min-width: 200px;
  }

  .card-title {
    font-size: 1.25rem;
  }
}

/* ===================================
           DEMO LAYOUT
           =================================== */
.layout-demo {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-top: 1rem;
}

.sidebar {
  flex: 1;
  min-width: 200px;
}

.main-content {
  flex: 2;
  min-width: 250px;
}

.demo-section {
  background-color: #0a0a1a;
  border-radius: 1rem;
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.demo-section h3 {
  color: #4a90e2;
  margin-bottom: 1rem;
}

.code-block {
  background-color: #0a0a1a;
  padding: 1rem;
  border-radius: 0.75rem;
  font-family: "Courier New", monospace;
  font-size: 0.8rem;
  color: #82b1ff;
  overflow-x: auto;
  margin: 1rem 0;
  border: 1px solid #1a1a2e;
}

.note {
  background-color: #1a1a2e;
  border-left: 4px solid #e94560;
  padding: 1rem;
  border-radius: 0.5rem;
  margin: 1rem 0;
}

footer {
  text-align: center;
  padding: 2rem;
  color: #666;
  font-size: 0.875rem;
}