CSS Commands Reference Guide

selector {
  property: value;
  /* This is a CSS comment */
}

/* Single line comment */

/*
Multi-line
comment
*/

/* Import another CSS file */
@import url('styles.css');

/* Define character encoding */
@charset 'UTF-8';

/* Define custom fonts */
@font-face {
  font-family: 'MyFont';
  src: url('myfont.woff2') format('woff2');
}

/* Media queries for responsive design */
@media (max-width: 768px) {
  body { font-size: 14px; }
}

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

/* Class selector */
.classname { font-weight: bold; }

/* ID selector */
#elementid { background: yellow; }

/* Universal selector */
* { margin: 0; padding: 0; }

/* Descendant selector */
div p { line-height: 1.5; }

/* Child selector */
div > p { color: red; }

/* Adjacent sibling selector */
h1 + p { margin-top: 0; }

/* General sibling selector */
h1 ~ p { font-style: italic; }

/* Link states */
a:link { color: blue; }
a:visited { color: purple; }
a:hover { text-decoration: underline; }
a:active { color: red; }

/* Form states */
input:focus { border-color: blue; }
input:disabled { opacity: 0.5; }
input:checked { background: green; }

/* Structural pseudo-classes */
li:first-child { font-weight: bold; }
li:last-child { border-bottom: none; }
li:nth-child(odd) { background: #f2f2f2; }
li:nth-child(3n) { color: green; }

.element {
  width: 300px;           /* Fixed width */
  min-width: 100px;       /* Minimum width */
  max-width: 500px;       /* Maximum width */
  height: 200px;          /* Fixed height */
  min-height: 50px;       /* Minimum height */
  max-height: 400px;      /* Maximum height */
  box-sizing: border-box; /* Include padding and border in dimensions */
}

.element {
  margin: 10px;            /* All sides */
  margin: 10px 20px;       /* Top/bottom, right/left */
  margin: 5px 10px 15px;   /* Top, right/left, bottom */
  margin: 5px 10px 15px 20px; /* Top, right, bottom, left */
  
  padding: 10px;           /* All sides */
  padding: 10px 20px;      /* Top/bottom, right/left */
  padding: 5px 10px 15px;  /* Top, right/left, bottom */
  padding: 5px 10px 15px 20px; /* Top, right, bottom, left */
}

.container {
  display: flex;
  flex-direction: row;           /* row, row-reverse, column, column-reverse */
  flex-wrap: nowrap;             /* nowrap, wrap, wrap-reverse */
  justify-content: flex-start;   /* flex-start, flex-end, center, space-between, space-around, space-evenly */
  align-items: stretch;          /* stretch, flex-start, flex-end, center, baseline */
  align-content: stretch;        /* stretch, flex-start, flex-end, center, space-between, space-around */
  gap: 10px;                     /* Space between flex items */
}

.item {
  flex: 1;                       /* flex-grow, flex-shrink, flex-basis */
  flex-grow: 0;                  /* How much item grows relative to others */
  flex-shrink: 1;                /* How much item shrinks relative to others */
  flex-basis: auto;              /* Default size before growing/shrinking */
  align-self: auto;              /* Override align-items for specific item */
  order: 0;                      /* Visual order (doesn't affect source order) */
}

.container {
  display: grid;
  grid-template-columns: 1fr 2fr 1fr;  /* Track sizes */
  grid-template-rows: 100px auto 100px;
  grid-template-areas: 
    "header header header"
    "sidebar content ads"
    "footer footer footer";
  gap: 20px;                      /* Space between grid items */
  justify-items: stretch;         /* stretch, start, end, center */
  align-items: stretch;           /* stretch, start, end, center */
}

.item {
  grid-column: 1 / 3;            /* Start / end */
  grid-row: 2;                   /* Row position */
  grid-area: header;             /* Named grid area */
  justify-self: center;          /* Individual alignment */
  align-self: center;
}

.text {
  font-family: Arial, Helvetica, sans-serif; /* Font stack */
  font-size: 16px;          /* Absolute size */
  font-size: 1rem;          /* Relative to root */
  font-size: 1.2em;         /* Relative to parent */
  font-weight: normal;      /* normal, bold, 100-900 */
  font-style: normal;       /* normal, italic, oblique */
  font-variant: normal;     /* normal, small-caps */
  line-height: 1.5;         /* Unitless multiplier or fixed value */
}

.text {
  color: #333;              /* Text color */
  text-align: left;         /* left, right, center, justify */
  text-decoration: none;    /* none, underline, overline, line-through */
  text-transform: none;     /* none, capitalize, uppercase, lowercase */
  text-indent: 20px;        /* First line indent */
  letter-spacing: 1px;      /* Space between letters */
  word-spacing: 2px;        /* Space between words */
  white-space: normal;      /* normal, nowrap, pre, pre-wrap, pre-line */
  word-wrap: break-word;    /* break-word, normal */
  text-shadow: 1px 1px 2px rgba(0,0,0,0.5); /* x-offset, y-offset, blur, color */
}

.element {
  color: red;                     /* Named color */
  color: #ff0000;                 /* Hex color */
  color: rgb(255, 0, 0);          /* RGB */
  color: rgba(255, 0, 0, 0.5);    /* RGB with alpha */
  color: hsl(0, 100%, 50%);       /* HSL */
  color: hsla(0, 100%, 50%, 0.5); /* HSL with alpha */
  color: currentColor;            /* Use current text color */
}

.element {
  background-color: #fff;
  background-image: url('image.jpg');
  background-repeat: no-repeat;   /* repeat, repeat-x, repeat-y, no-repeat */
  background-position: center;    /* x-position y-position */
  background-size: cover;         /* cover, contain, or specific dimensions */
  background-attachment: fixed;   /* scroll, fixed, local */
  
  /* Shorthand */
  background: #fff url('image.jpg') no-repeat center / cover fixed;
}

.element {
  position: static;    /* Default, normal flow */
  position: relative;  /* Positioned relative to normal position */
  position: absolute;  /* Positioned relative to nearest positioned ancestor */
  position: fixed;     /* Positioned relative to viewport */
  position: sticky;    /* Toggles between relative and fixed based on scroll */
}

.element {
  top: 10px;
  right: 20px;
  bottom: 30px;
  left: 40px;
  z-index: 10; /* Stacking context, higher numbers appear on top */
}

.element {
  transition: all 0.3s ease-in-out; /* property duration timing-function delay */
  transition-property: opacity, transform;
  transition-duration: 0.3s;
  transition-timing-function: ease-in-out; /* ease, linear, ease-in, ease-out, ease-in-out, cubic-bezier() */
  transition-delay: 0.1s;
}

.element {
  animation: pulse 2s infinite; /* name duration timing-function delay iteration-count direction fill-mode */
  animation-name: pulse;
  animation-duration: 2s;
  animation-timing-function: ease-in-out;
  animation-delay: 0s;
  animation-iteration-count: infinite;
  animation-direction: alternate;
}

@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.1); }
  100% { transform: scale(1); }
}

/* Default styles for mobile first */

/* Tablet */
@media (min-width: 768px) {
  .element { width: 750px; }
}

/* Desktop */
@media (min-width: 992px) {
  .element { width: 970px; }
}

/* Large desktop */
@media (min-width: 1200px) {
  .element { width: 1170px; }
}

/* Specific device orientation */
@media (orientation: landscape) {
  .element { height: 100vh; }
}

.element {
  width: 100vw;     /* 100% of viewport width */
  height: 50vh;     /* 50% of viewport height */
  font-size: 4vmin; /* 4% of viewport's smaller dimension */
  padding: 2vmax;   /* 2% of viewport's larger dimension */
}

.element {
  width: calc(100% - 80px);
  height: calc(50vh + 10px);
}

:root {
  --main-color: #3498db;
  --padding: 15px;
  --max-width: 1200px;
}

.element {
  color: var(--main-color);
  padding: var(--padding);
  max-width: var(--max-width);
  background-color: var(--fallback-color, #f2f2f2); /* With fallback */
}

/* Method 1: Flexbox */
.container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

/* Method 2: Grid */
.container {
  display: grid;
  place-items: center;
  height: 100vh;
}

/* Method 3: Absolute positioning */
.container {
  position: relative;
  height: 100vh;
}

.centered-element {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.btn {
  display: inline-block;
  padding: 12px 24px;
  background-color: #3498db;
  color: white;
  text-decoration: none;
  border-radius: 4px;
  font-weight: bold;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
}

.btn:hover {
  background-color: #2980b9;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.btn:active {
  transform: translateY(0);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}