Flexbox

Flexbox Layout System

Create flexible, responsive layouts with ease. Flexbox is perfect for one-dimensional layouts (rows or columns).

💻 Flexbox Basics

/* Enable Flexbox */
.container {
    display: flex;      /* Block-level flex container */
    /* OR */
    display: inline-flex;  /* Inline-level flex container */
}

/* Basic terminology */
/* Container: Element with display: flex */
/* Items: Direct children of container */
/* Main axis: Primary direction (default: horizontal) */
/* Cross axis: Perpendicular to main axis */

🎯 Container Properties

flex-direction

/* Direction of main axis */
.container {
    display: flex;
    flex-direction: row;           /* Default: left to right */
    flex-direction: row-reverse;   /* Right to left */
    flex-direction: column;        /* Top to bottom */
    flex-direction: column-reverse; /* Bottom to top */
}

/* Example: Vertical layout */
.vertical {
    display: flex;
    flex-direction: column;
}

flex-wrap

/* Control wrapping */
.container {
    display: flex;
    flex-wrap: nowrap;     /* Default: single line */
    flex-wrap: wrap;       /* Multi-line */
    flex-wrap: wrap-reverse; /* Multi-line, reversed */
}

/* Example: Wrap items */
.gallery {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

flex-flow (Shorthand)

/* Combines direction and wrap */
.container {
    display: flex;
    flex-flow: row wrap;
    /* Same as: */
    /* flex-direction: row; */
    /* flex-wrap: wrap; */
}

.container {
    flex-flow: column nowrap;
}

justify-content (Main Axis)

/* Align items on main axis */
.container {
    display: flex;
    justify-content: flex-start;    /* Default: start */
    justify-content: flex-end;      /* End */
    justify-content: center;        /* Center */
    justify-content: space-between; /* Equal space between */
    justify-content: space-around;  /* Equal space around */
    justify-content: space-evenly;  /* Equal space everywhere */
}

/* Examples */
.nav {
    display: flex;
    justify-content: space-between;
}

.buttons {
    display: flex;
    justify-content: center;
    gap: 10px;
}

align-items (Cross Axis)

/* Align items on cross axis */
.container {
    display: flex;
    align-items: stretch;     /* Default: fill container */
    align-items: flex-start;  /* Start of cross axis */
    align-items: flex-end;    /* End of cross axis */
    align-items: center;      /* Center */
    align-items: baseline;    /* Baseline of text */
}

/* Examples */
.card {
    display: flex;
    align-items: center;
    padding: 20px;
}

.header {
    display: flex;
    align-items: baseline;
}

align-content (Multiple Lines)

/* Align lines when wrapping */
.container {
    display: flex;
    flex-wrap: wrap;
    align-content: flex-start;    /* Lines at start */
    align-content: flex-end;      /* Lines at end */
    align-content: center;        /* Lines centered */
    align-content: space-between; /* Space between lines */
    align-content: space-around;  /* Space around lines */
    align-content: stretch;       /* Default: stretch lines */
}

/* Only works with flex-wrap: wrap */

gap

/* Space between items */
.container {
    display: flex;
    gap: 20px;              /* Space between all items */
    
    /* OR separate values */
    gap: 10px 20px;         /* row-gap column-gap */
    
    /* OR individual properties */
    row-gap: 10px;
    column-gap: 20px;
}

/* Much cleaner than using margins */
.grid {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

🎨 Item Properties

flex-grow

/* How much item grows relative to others */
.item {
    flex-grow: 0;    /* Default: don't grow */
    flex-grow: 1;    /* Grow to fill space */
    flex-grow: 2;    /* Grow twice as much */
}

/* Example: Flexible columns */
.sidebar {
    flex-grow: 0;
    width: 250px;
}

.content {
    flex-grow: 1;    /* Takes remaining space */
}

flex-shrink

/* How much item shrinks when space is limited */
.item {
    flex-shrink: 1;    /* Default: can shrink */
    flex-shrink: 0;    /* Don't shrink */
    flex-shrink: 2;    /* Shrink twice as much */
}

/* Example: Fixed sidebar */
.sidebar {
    flex-shrink: 0;
    width: 250px;    /* Won't shrink below 250px */
}

.content {
    flex-shrink: 1;  /* Will shrink if needed */
}

flex-basis

/* Initial size before growing/shrinking */
.item {
    flex-basis: auto;     /* Default: based on content */
    flex-basis: 200px;    /* Fixed size */
    flex-basis: 50%;      /* Percentage */
    flex-basis: 0;        /* Ignore content size */
}

/* Example: Equal width columns */
.column {
    flex-basis: 0;
    flex-grow: 1;
}

flex (Shorthand)

/* Combines grow, shrink, basis */
.item {
    flex: 0 1 auto;    /* Default: grow shrink basis */
    flex: 1;           /* Same as: 1 1 0% */
    flex: 2;           /* Same as: 2 1 0% */
    flex: 0 0 200px;   /* Fixed 200px */
}

/* Common patterns */
.equal-width {
    flex: 1;           /* Equal width columns */
}

.fixed-width {
    flex: 0 0 250px;   /* Fixed 250px */
}

.auto-width {
    flex: 0 1 auto;    /* Based on content */
}

align-self

/* Override align-items for single item */
.container {
    display: flex;
    align-items: center;
}

.special-item {
    align-self: flex-start;  /* Override to flex-start */
    align-self: flex-end;
    align-self: center;
    align-self: baseline;
    align-self: stretch;
}

/* Example: Different alignment */
.header .logo {
    align-self: center;
}

.header .user-menu {
    align-self: flex-end;
}

order

/* Change visual order */
.item {
    order: 0;    /* Default */
}

.item-first {
    order: -1;   /* Appears first */
}

.item-last {
    order: 1;    /* Appears last */
}

/* Example: Reorder on mobile */
@media (max-width: 768px) {
    .sidebar {
        order: 2;   /* Move sidebar after content */
    }
    
    .content {
        order: 1;
    }
}

🎯 Practical Examples

/* Navigation bar */
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
}

nav .logo {
    flex: 0 0 auto;
}

nav .menu {
    display: flex;
    gap: 2rem;
}

nav .actions {
    display: flex;
    gap: 1rem;
}

/* Card layout */
.card {
    display: flex;
    gap: 20px;
    padding: 20px;
    border: 1px solid #ddd;
    border-radius: 8px;
}

.card img {
    flex: 0 0 150px;
    height: 150px;
    object-fit: cover;
    border-radius: 4px;
}

.card-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

/* Gallery grid */
.gallery {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.gallery-item {
    flex: 1 1 300px;    /* Grow, shrink, min 300px */
    max-width: 400px;
}

.gallery-item img {
    width: 100%;
    height: 250px;
    object-fit: cover;
    border-radius: 8px;
}

/* Centered content */
.center-box {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

/* Sticky footer */
body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1;    /* Takes remaining space */
}

footer {
    flex: 0 0 auto;
}

/* Form layout */
.form-row {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
}

.form-row .field {
    flex: 1;
}

.form-row .field.small {
    flex: 0 0 150px;
}

/* Dashboard layout */
.dashboard {
    display: flex;
    gap: 20px;
    padding: 20px;
}

.sidebar {
    flex: 0 0 250px;
    background: #f5f5f5;
    padding: 20px;
    border-radius: 8px;
}

.main-content {
    flex: 1;
}

.widget-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.widget {
    flex: 1 1 300px;
    min-height: 200px;
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

/* Button group */
.button-group {
    display: flex;
    gap: 10px;
}

.button-group.vertical {
    flex-direction: column;
}

.button-group.spread {
    justify-content: space-between;
}

.button-group button {
    flex: 1;
    padding: 10px 20px;
}

/* Pricing cards */
.pricing {
    display: flex;
    gap: 20px;
    justify-content: center;
}

.pricing-card {
    flex: 0 1 300px;
    display: flex;
    flex-direction: column;
    padding: 30px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    text-align: center;
}

.pricing-card.featured {
    border-color: #007bff;
    transform: scale(1.05);
}

.pricing-card h3 {
    margin-bottom: 20px;
}

.pricing-card .price {
    font-size: 2rem;
    font-weight: bold;
    margin-bottom: 20px;
}

.pricing-card .features {
    flex: 1;
    text-align: left;
    margin-bottom: 20px;
}

.pricing-card button {
    margin-top: auto;
}

🎯 Key Takeaways

display: flex: Enable flexbox on container
flex-direction: row (horizontal) or column (vertical)
justify-content: Align items on main axis
align-items: Align items on cross axis
flex-wrap: Allow items to wrap to multiple lines
gap: Space between items (cleaner than margins)
flex: Shorthand for grow, shrink, basis
Flexbox is one-dimensional: Use Grid for two-dimensional layouts