CSS Fundamentals

/* Element selector */
p { color: blue; }

/* Class selector */
.button { padding: 10px; }

/* ID selector (avoid in production) */
#header { background: white; }

/* Attribute selector */
input[type="email"] { border: 1px solid gray; }

/* Combinators */
nav > ul { list-style: none; }
article p { margin: 1rem 0; }

div {
  width: 200px;
  padding: 20px;      /* Inside the box */
  border: 1px solid;
  margin: 10px;       /* Outside the box */
}

/* Block, inline, inline-block */
div { display: block; }
span { display: inline; }
button { display: inline-block; }

/* Flexbox */
.container { 
  display: flex;
  gap: 1rem;
  align-items: center;
}

/* Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

/* Mobile first */
body { font-size: 14px; }

/* Tablet and up */
@media (min-width: 768px) {
  body { font-size: 16px; }
}

/* Desktop and up */
@media (min-width: 1024px) {
  body { font-size: 18px; }
}