/* ===== Reset & Base Styles ===== */
:root {
    /* Color Variables */
    --b4-primary: #3f6ad8;
    --b4-secondary: #6c757d;
    --b4-success: #3ac47d;
    --b4-info: #16aaff;
    --b4-warning: #f7b924;
    --b4-danger: #d92550;
    --b4-light: #f8f9fa;
    --b4-dark: #343a40;
    --b4-muted: #6c757d;
    --b4-white: #ffffff;
    --b4-black: #000000;
    
    /* Typography */
    --b4-font-sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --b4-font-mono: SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
    
    /* Spacing */
    --b4-spacing-0: 0;
    --b4-spacing-1: 0.25rem;
    --b4-spacing-2: 0.5rem;
    --b4-spacing-3: 1rem;
    --b4-spacing-4: 1.5rem;
    --b4-spacing-5: 3rem;
    
    /* Shadow */
    --b4-shadow-sm: 0 .125rem .25rem rgba(0,0,0,.075);
    --b4-shadow: 0 .5rem 1rem rgba(0,0,0,.15);
    --b4-shadow-lg: 0 1rem 3rem rgba(0,0,0,.175);
    
    /* Border Radius */
    --b4-rounded: 0.25rem;
    --b4-rounded-lg: 0.5rem;
    
    /* Transition */
    --b4-transition: all .2s ease-in-out;
    
    /* Z-index */
    --b4-z-dropdown: 1000;
    --b4-z-fixed: 1030;
    --b4-z-modal: 1050;
  }
  
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  html {
    font-size: 16px;
    scroll-behavior: smooth;
  }
  
  body {
    font-family: var(--b4-font-sans);
    line-height: 1.5;
    color: var(--b4-dark);
    background-color: var(--b4-white);
  }
  
  /* Headings */
  h1, h2, h3, h4, h5, h6 {
    margin-bottom: 0.5rem;
    font-weight: 500;
    line-height: 1.2;
  }
  
  h1 { font-size: 2.5rem; }
  h2 { font-size: 2rem; }
  h3 { font-size: 1.75rem; }
  h4 { font-size: 1.5rem; }
  h5 { font-size: 1.25rem; }
  h6 { font-size: 1rem; }
  
  p {
    margin-bottom: 1rem;
  }
  
  a {
    color: var(--b4-primary);
    text-decoration: none;
    transition: var(--b4-transition);
  }
  
  a:hover {
    text-decoration: underline;
  }
  
  img {
    max-width: 100%;
    height: auto;
  }
  
  code, pre {
    font-family: var(--b4-font-mono);
    font-size: 0.875em;
  }
  
  pre {
    display: block;
    padding: 1rem;
    overflow: auto;
    background-color: #f8f9fa;
    border-radius: var(--b4-rounded);
  }
  
  /* ===== Container & Grid System ===== */
  .b4-container {
    width: 100%;
    padding-right: 15px;
    padding-left: 15px;
    margin-right: auto;
    margin-left: auto;
  }
  
  @media (min-width: 576px) {
    .b4-container {
      max-width: 540px;
    }
  }
  
  @media (min-width: 768px) {
    .b4-container {
      max-width: 720px;
    }
  }
  
  @media (min-width: 992px) {
    .b4-container {
      max-width: 960px;
    }
  }
  
  @media (min-width: 1200px) {
    .b4-container {
      max-width: 1140px;
    }
  }
  
  .b4-row {
    display: flex;
    flex-wrap: wrap;
    margin-right: -15px;
    margin-left: -15px;
  }
  
  /* Column base */
  [class*="b4-col-"] {
    position: relative;
    width: 100%;
    padding-right: 15px;
    padding-left: 15px;
  }
  
  /* Column widths for different breakpoints */
  .b4-col-1 { flex: 0 0 8.333333%; max-width: 8.333333%; }
  .b4-col-2 { flex: 0 0 16.666667%; max-width: 16.666667%; }
  .b4-col-3 { flex: 0 0 25%; max-width: 25%; }
  .b4-col-4 { flex: 0 0 33.333333%; max-width: 33.333333%; }
  .b4-col-5 { flex: 0 0 41.666667%; max-width: 41.666667%; }
  .b4-col-6 { flex: 0 0 50%; max-width: 50%; }
  .b4-col-7 { flex: 0 0 58.333333%; max-width: 58.333333%; }
  .b4-col-8 { flex: 0 0 66.666667%; max-width: 66.666667%; }
  .b4-col-9 { flex: 0 0 75%; max-width: 75%; }
  .b4-col-10 { flex: 0 0 83.333333%; max-width: 83.333333%; }
  .b4-col-11 { flex: 0 0 91.666667%; max-width: 91.666667%; }
  .b4-col-12 { flex: 0 0 100%; max-width: 100%; }
  
  /* MD breakpoint (768px) */
  @media (min-width: 768px) {
    .b4-col-md-1 { flex: 0 0 8.333333%; max-width: 8.333333%; }
    .b4-col-md-2 { flex: 0 0 16.666667%; max-width: 16.666667%; }
    .b4-col-md-3 { flex: 0 0 25%; max-width: 25%; }
    .b4-col-md-4 { flex: 0 0 33.333333%; max-width: 33.333333%; }
    .b4-col-md-5 { flex: 0 0 41.666667%; max-width: 41.666667%; }
    .b4-col-md-6 { flex: 0 0 50%; max-width: 50%; }
    .b4-col-md-7 { flex: 0 0 58.333333%; max-width: 58.333333%; }
    .b4-col-md-8 { flex: 0 0 66.666667%; max-width: 66.666667%; }
    .b4-col-md-9 { flex: 0 0 75%; max-width: 75%; }
    .b4-col-md-10 { flex: 0 0 83.333333%; max-width: 83.333333%; }
    .b4-col-md-11 { flex: 0 0 91.666667%; max-width: 91.666667%; }
    .b4-col-md-12 { flex: 0 0 100%; max-width: 100%; }
  }
  
  /* LG breakpoint (992px) */
  @media (min-width: 992px) {
    .b4-col-lg-1 { flex: 0 0 8.333333%; max-width: 8.333333%; }
    .b4-col-lg-2 { flex: 0 0 16.666667%; max-width: 16.666667%; }
    .b4-col-lg-3 { flex: 0 0 25%; max-width: 25%; }
    .b4-col-lg-4 { flex: 0 0 33.333333%; max-width: 33.333333%; }
    .b4-col-lg-5 { flex: 0 0 41.666667%; max-width: 41.666667%; }
    .b4-col-lg-6 { flex: 0 0 50%; max-width: 50%; }
    .b4-col-lg-7 { flex: 0 0 58.333333%; max-width: 58.333333%; }
    .b4-col-lg-8 { flex: 0 0 66.666667%; max-width: 66.666667%; }
    .b4-col-lg-9 { flex: 0 0 75%; max-width: 75%; }
    .b4-col-lg-10 { flex: 0 0 83.333333%; max-width: 83.333333%; }
    .b4-col-lg-11 { flex: 0 0 91.666667%; max-width: 91.666667%; }
    .b4-col-lg-12 { flex: 0 0 100%; max-width: 100%; }
  }
  
  /* ===== Typography Utilities ===== */
  /* Text sizes */
  .b4-text-xs { font-size: 0.75rem; }
  .b4-text-sm { font-size: 0.875rem; }
  .b4-text-base { font-size: 1rem; }
  .b4-text-lg { font-size: 1.125rem; }
  .b4-text-xl { font-size: 1.25rem; }
  .b4-text-2xl { font-size: 1.5rem; }
  .b4-text-3xl { font-size: 1.875rem; }
  .b4-text-4xl { font-size: 2.25rem; }
  .b4-text-5xl { font-size: 3rem; }
  
  /* Font weights */
  .b4-font-light { font-weight: 300; }
  .b4-font-normal { font-weight: 400; }
  .b4-font-medium { font-weight: 500; }
  .b4-font-semibold { font-weight: 600; }
  .b4-font-bold { font-weight: 700; }
  
  /* Text alignment */
  .b4-text-left { text-align: left; }
  .b4-text-center { text-align: center; }
  .b4-text-right { text-align: right; }
  
  /* Text colors */
  .b4-text-primary { color: var(--b4-primary); }
  .b4-text-secondary { color: var(--b4-secondary); }
  .b4-text-success { color: var(--b4-success); }
  .b4-text-info { color: var(--b4-info); }
  .b4-text-warning { color: var(--b4-warning); }
  .b4-text-danger { color: var(--b4-danger); }
  .b4-text-light { color: var(--b4-light); }
  .b4-text-dark { color: var(--b4-dark); }
  .b4-text-muted { color: var(--b4-muted); }
  .b4-text-white { color: var(--b4-white); }
  
  /* Text transform */
  .b4-uppercase { text-transform: uppercase; }
  .b4-lowercase { text-transform: lowercase; }
  .b4-capitalize { text-transform: capitalize; }
  
  /* ===== Spacing Utilities ===== */
  /* Margin */
  .b4-m-0 { margin: var(--b4-spacing-0); }
  .b4-m-1 { margin: var(--b4-spacing-1); }
  .b4-m-2 { margin: var(--b4-spacing-2); }
  .b4-m-3 { margin: var(--b4-spacing-3); }
  .b4-m-4 { margin: var(--b4-spacing-4); }
  .b4-m-5 { margin: var(--b4-spacing-5); }
  
  .b4-mt-0 { margin-top: var(--b4-spacing-0); }
  .b4-mt-1 { margin-top: var(--b4-spacing-1); }
  .b4-mt-2 { margin-top: var(--b4-spacing-2); }
  .b4-mt-3 { margin-top: var(--b4-spacing-3); }
  .b4-mt-4 { margin-top: var(--b4-spacing-4); }
  .b4-mt-5 { margin-top: var(--b4-spacing-5); }
  
  .b4-mb-0 { margin-bottom: var(--b4-spacing-0); }
  .b4-mb-1 { margin-bottom: var(--b4-spacing-1); }
  .b4-mb-2 { margin-bottom: var(--b4-spacing-2); }
  .b4-mb-3 { margin-bottom: var(--b4-spacing-3); }
  .b4-mb-4 { margin-bottom: var(--b4-spacing-4); }
  .b4-mb-5 { margin-bottom: var(--b4-spacing-5); }
  
  .b4-ml-0 { margin-left: var(--b4-spacing-0); }
  .b4-ml-1 { margin-left: var(--b4-spacing-1); }
  .b4-ml-2 { margin-left: var(--b4-spacing-2); }
  .b4-ml-3 { margin-left: var(--b4-spacing-3); }
  .b4-ml-4 { margin-left: var(--b4-spacing-4); }
  .b4-ml-5 { margin-left: var(--b4-spacing-5); }
  
  .b4-mr-0 { margin-right: var(--b4-spacing-0); }
  .b4-mr-1 { margin-right: var(--b4-spacing-1); }
  .b4-mr-2 { margin-right: var(--b4-spacing-2); }
  .b4-mr-3 { margin-right: var(--b4-spacing-3); }
  .b4-mr-4 { margin-right: var(--b4-spacing-4); }
  .b4-mr-5 { margin-right: var(--b4-spacing-5); }
  
  .b4-mx-0 { margin-left: var(--b4-spacing-0); margin-right: var(--b4-spacing-0); }
  .b4-mx-1 { margin-left: var(--b4-spacing-1); margin-right: var(--b4-spacing-1); }
  .b4-mx-2 { margin-left: var(--b4-spacing-2); margin-right: var(--b4-spacing-2); }
  .b4-mx-3 { margin-left: var(--b4-spacing-3); margin-right: var(--b4-spacing-3); }
  .b4-mx-4 { margin-left: var(--b4-spacing-4); margin-right: var(--b4-spacing-4); }
  .b4-mx-5 { margin-left: var(--b4-spacing-5); margin-right: var(--b4-spacing-5); }
  
  .b4-my-0 { margin-top: var(--b4-spacing-0); margin-bottom: var(--b4-spacing-0); }
  .b4-my-1 { margin-top: var(--b4-spacing-1); margin-bottom: var(--b4-spacing-1); }
  .b4-my-2 { margin-top: var(--b4-spacing-2); margin-bottom: var(--b4-spacing-2); }
  .b4-my-3 { margin-top: var(--b4-spacing-3); margin-bottom: var(--b4-spacing-3); }
  .b4-my-4 { margin-top: var(--b4-spacing-4); margin-bottom: var(--b4-spacing-4); }
  .b4-my-5 { margin-top: var(--b4-spacing-5); margin-bottom: var(--b4-spacing-5); }
  
  /* Padding */
  .b4-p-0 { padding: var(--b4-spacing-0); }
  .b4-p-1 { padding: var(--b4-spacing-1); }
  .b4-p-2 { padding: var(--b4-spacing-2); }
  .b4-p-3 { padding: var(--b4-spacing-3); }
  .b4-p-4 { padding: var(--b4-spacing-4); }
  .b4-p-5 { padding: var(--b4-spacing-5); }
  
  .b4-pt-0 { padding-top: var(--b4-spacing-0); }
  .b4-pt-1 { padding-top: var(--b4-spacing-1); }
  .b4-pt-2 { padding-top: var(--b4-spacing-2); }
  .b4-pt-3 { padding-top: var(--b4-spacing-3); }
  .b4-pt-4 { padding-top: var(--b4-spacing-4); }
  .b4-pt-5 { padding-top: var(--b4-spacing-5); }
  
  .b4-pb-0 { padding-bottom: var(--b4-spacing-0); }
  .b4-pb-1 { padding-bottom: var(--b4-spacing-1); }
  .b4-pb-2 { padding-bottom: var(--b4-spacing-2); }
  .b4-pb-3 { padding-bottom: var(--b4-spacing-3); }
  .b4-pb-4 { padding-bottom: var(--b4-spacing-4); }
  .b4-pb-5 { padding-bottom: var(--b4-spacing-5); }
  
  .b4-pl-0 { padding-left: var(--b4-spacing-0); }
  .b4-pl-1 { padding-left: var(--b4-spacing-1); }
  .b4-pl-2 { padding-left: var(--b4-spacing-2); }
  .b4-pl-3 { padding-left: var(--b4-spacing-3); }
  .b4-pl-4 { padding-left: var(--b4-spacing-4); }
  .b4-pl-5 { padding-left: var(--b4-spacing-5); }
  
  .b4-pr-0 { padding-right: var(--b4-spacing-0); }
  .b4-pr-1 { padding-right: var(--b4-spacing-1); }
  .b4-pr-2 { padding-right: var(--b4-spacing-2); }
  .b4-pr-3 { padding-right: var(--b4-spacing-3); }
  .b4-pr-4 { padding-right: var(--b4-spacing-4); }
  .b4-pr-5 { padding-right: var(--b4-spacing-5); }
  
  .b4-px-0 { padding-left: var(--b4-spacing-0); padding-right: var(--b4-spacing-0); }
  .b4-px-1 { padding-left: var(--b4-spacing-1); padding-right: var(--b4-spacing-1); }
  .b4-px-2 { padding-left: var(--b4-spacing-2); padding-right: var(--b4-spacing-2); }
  .b4-px-3 { padding-left: var(--b4-spacing-3); padding-right: var(--b4-spacing-3); }
  .b4-px-4 { padding-left: var(--b4-spacing-4); padding-right: var(--b4-spacing-4); }
  .b4-px-5 { padding-left: var(--b4-spacing-5); padding-right: var(--b4-spacing-5); }
  
  .b4-py-0 { padding-top: var(--b4-spacing-0); padding-bottom: var(--b4-spacing-0); }
  .b4-py-1 { padding-top: var(--b4-spacing-1); padding-bottom: var(--b4-spacing-1); }
  .b4-py-2 { padding-top: var(--b4-spacing-2); padding-bottom: var(--b4-spacing-2); }
  .b4-py-3 { padding-top: var(--b4-spacing-3); padding-bottom: var(--b4-spacing-3); }
  .b4-py-4 { padding-top: var(--b4-spacing-4); padding-bottom: var(--b4-spacing-4); }
  .b4-py-5 { padding-top: var(--b4-spacing-5); padding-bottom: var(--b4-spacing-5); }
  
  /* ===== Flexbox Utilities ===== */
  .b4-flex { display: flex; }
  .b4-inline-flex { display: inline-flex; }
  
  .b4-flex-row { flex-direction: row; }
  .b4-flex-col { flex-direction: column; }
  .b4-flex-row-reverse { flex-direction: row-reverse; }
  .b4-flex-col-reverse { flex-direction: column-reverse; }
  
  .b4-flex-wrap { flex-wrap: wrap; }
  .b4-flex-nowrap { flex-wrap: nowrap; }
  
  .b4-justify-start { justify-content: flex-start; }
  .b4-justify-end { justify-content: flex-end; }
  .b4-justify-center { justify-content: center; }
  .b4-justify-between { justify-content: space-between; }
  .b4-justify-around { justify-content: space-around; }
  .b4-justify-evenly { justify-content: space-evenly; }
  
  .b4-items-start { align-items: flex-start; }
  .b4-items-end { align-items: flex-end; }
  .b4-items-center { align-items: center; }
  .b4-items-baseline { align-items: baseline; }
  .b4-items-stretch { align-items: stretch; }
  
  .b4-content-start { align-content: flex-start; }
  .b4-content-end { align-content: flex-end; }
  .b4-content-center { align-content: center; }
  .b4-content-between { align-content: space-between; }
  .b4-content-around { align-content: space-around; }
  .b4-content-stretch { align-content: stretch; }
  
  .b4-self-auto { align-self: auto; }
  .b4-self-start { align-self: flex-start; }
  .b4-self-end { align-self: flex-end; }
  .b4-self-center { align-self: center; }
  .b4-self-stretch { align-self: stretch; }
  
  /* ===== Border & Border Radius ===== */
  .b4-border { border: 1px solid #dee2e6; }
  .b4-border-0 { border: 0; }
  .b4-border-top { border-top: 1px solid #dee2e6; }
  .b4-border-right { border-right: 1px solid #dee2e6; }
  .b4-border-bottom { border-bottom: 1px solid #dee2e6; }
  .b4-border-left { border-left: 1px solid #dee2e6; }
  
  .b4-border-primary { border-color: var(--b4-primary); }
  .b4-border-secondary { border-color: var(--b4-secondary); }
  .b4-border-success { border-color: var(--b4-success); }
  .b4-border-info { border-color: var(--b4-info); }
  .b4-border-warning { border-color: var(--b4-warning); }
  .b4-border-danger { border-color: var(--b4-danger); }
  .b4-border-light { border-color: var(--b4-light); }
  .b4-border-dark { border-color: var(--b4-dark); }
  
  .b4-rounded { border-radius: var(--b4-rounded); }
  .b4-rounded-lg { border-radius: var(--b4-rounded-lg); }
  .b4-rounded-none { border-radius: 0; }
  .b4-rounded-circle { border-radius: 50%; }
  .b4-rounded-l { border-top-left-radius: var(--b4-rounded); border-bottom-left-radius: var(--b4-rounded); }
  .b4-rounded-r { border-top-right-radius: var(--b4-rounded); border-bottom-right-radius: var(--b4-rounded); }
  .b4-rounded-t { border-top-left-radius: var(--b4-rounded); border-top-right-radius: var(--b4-rounded); }
  .b4-rounded-b { border-bottom-left-radius: var(--b4-rounded); border-bottom-right-radius: var(--b4-rounded); }
  
  /* ===== Background Colors ===== */
  .b4-bg-primary { background-color: var(--b4-primary); }
  .b4-bg-secondary { background-color: var(--b4-secondary); }
  .b4-bg-success { background-color: var(--b4-success); }
  .b4-bg-info { background-color: var(--b4-info); }
  .b4-bg-warning { background-color: var(--b4-warning); }
  .b4-bg-danger { background-color: var(--b4-danger); }
  .b4-bg-light { background-color: var(--b4-light); }
  .b4-bg-dark { background-color: var(--b4-dark); }
  .b4-bg-white { background-color: var(--b4-white); }
  .b4-bg-transparent { background-color: transparent; }
  
  /* ===== Buttons ===== */
  .b4-btn {
    display: inline-block;
    font-weight: 400;
    color: #212529;
    text-align: center;
    vertical-align: middle;
    user-select: none;
    background-color: transparent;
    border: 1px solid transparent;
    padding: 0.375rem 0.75rem;
    font-size: 1rem;
    line-height: 1.5;
    border-radius: var(--b4-rounded);
    transition: var(--b4-transition);
    cursor: pointer;
  }
  
  .b4-btn:hover {
    text-decoration: none;
  }
  
  .b4-btn:focus {
    outline: 0;
    box-shadow: 0 0 0 0.2rem rgba(63, 106, 216, 0.25);
  }
  
  .b4-btn:disabled {
    opacity: 0.65;
    pointer-events: none;
  }
  
  /* Button Styles */
  .b4-btn-primary {
    color: var(--b4-white);
    background-color: var(--b4-primary);
    border-color: var(--b4-primary);
  }
  
  .b4-btn-primary:hover {
    background-color: #3053ab;
    border-color: #2d4ea0;
  }
  
  .b4-btn-secondary {
    color: var(--b4-white);
    background-color: var(--b4-secondary);
    border-color: var(--b4-secondary);
  }
  
  .b4-btn-secondary:hover {
    background-color: #545b62;
    border-color: #4e555b;
  }
  
  .b4-btn-success {
    color: var(--b4-white);
    background-color: var(--b4-success);
    border-color: var(--b4-success);
  }
  
  .b4-btn-success:hover {
    background-color: #31a66a;
    border-color: #2e9d64;
  }
  
  .b4-btn-danger {
    color: var(--b4-white);
    background-color: var(--b4-danger);
    border-color: var(--b4-danger);
  }
  
  .b4-btn-danger:hover {
    background-color: #b52045;
    border-color: #aa1e41;
  }
  
  .b4-btn-warning {
    color: #212529;
    background-color: var(--b4-warning);
    border-color: var(--b4-warning);
  }
  
  .b4-btn-warning:hover {
    background-color: #e0a800;
    border-color: #d39e00;
  }
  
  .b4-btn-info {
    color: var(--b4-white);
    background-color: var(--b4-info);
    border-color: var(--b4-info);
  }
  
  .b4-btn-info:hover {
    background-color: #0f8fdb;
    border-color: #0e86cf;
  }
  
  /* Outline Buttons */
  .b4-btn-outline-primary {
    color: var(--b4-primary);
    border-color: var(--b4-primary);
  }
  
  .b4-btn-outline-primary:hover {
    color: var(--b4-white);
    background-color: var(--b4-primary);
    border-color: var(--b4-primary);
  }
  
  .b4-btn-outline-secondary {
    color: var(--b4-secondary);
    border-color: var(--b4-secondary);
  }
  
  .b4-btn-outline-secondary:hover {
    color: var(--b4-white);
    background-color: var(--b4-secondary);
    border-color: var(--b4-secondary);
  }
  
  /* Button Sizes */
  .b4-btn-sm {
    padding: 0.25rem 0.5rem;
    font-size: 0.875rem;
    line-height: 1.5;
    border-radius: 0.2rem;
  }
  
  .b4-btn-lg {
    padding: 0.5rem 1rem;
    font-size: 1.25rem;
    line-height: 1.5;
    border-radius: 0.3rem;
  }
  /* ===== Cards ===== */
.b4-card {
    position: relative;
    display: flex;
    flex-direction: column;
    min-width: 0;
    word-wrap: break-word;
    background-color: var(--b4-white);
    background-clip: border-box;
    border: 1px solid rgba(0, 0, 0, 0.125);
    border-radius: var(--b4-rounded);
    box-shadow: var(--b4-shadow-sm);
    transition: var(--b4-transition);
  }
  
  .b4-card:hover {
    box-shadow: var(--b4-shadow);
  }
  
  .b4-card-body {
    flex: 1 1 auto;
    padding: 1.25rem;
  }
  
  .b4-card-title {
    margin-bottom: 0.75rem;
    font-size: 1.25rem;
    font-weight: 500;
  }
  
  .b4-card-subtitle {
    margin-top: -0.375rem;
    margin-bottom: 0.5rem;
    color: var(--b4-muted);
  }
  
  .b4-card-text:last-child {
    margin-bottom: 0;
  }
  
  .b4-card-header {
    padding: 0.75rem 1.25rem;
    margin-bottom: 0;
    background-color: rgba(0, 0, 0, 0.03);
    border-bottom: 1px solid rgba(0, 0, 0, 0.125);
  }
  
  .b4-card-footer {
    padding: 0.75rem 1.25rem;
    background-color: rgba(0, 0, 0, 0.03);
    border-top: 1px solid rgba(0, 0, 0, 0.125);
  }
  
  /* ===== Alerts ===== */
  .b4-alert {
    position: relative;
    padding: 0.75rem 1.25rem;
    margin-bottom: 1rem;
    border: 1px solid transparent;
    border-radius: var(--b4-rounded);
  }
  
  .b4-alert-primary {
    color: #1b3c7e;
    background-color: #d6e1fa;
    border-color: #c7d4f8;
  }
  
  .b4-alert-secondary {
    color: #383d41;
    background-color: #e2e3e5;
    border-color: #d6d8db;
  }
  
  .b4-alert-success {
    color: #155724;
    background-color: #d4edda;
    border-color: #c3e6cb;
  }
  
  .b4-alert-danger {
    color: #721c24;
    background-color: #f8d7da;
    border-color: #f5c6cb;
  }
  
  .b4-alert-warning {
    color: #856404;
    background-color: #fff3cd;
    border-color: #ffeeba;
  }
  
  .b4-alert-info {
    color: #0c5460;
    background-color: #d1ecf1;
    border-color: #bee5eb;
  }
  
  /* ===== Modal ===== */
  .b4-modal {
    position: fixed;
    top: 0;
    left: 0;
    z-index: var(--b4-z-modal);
    width: 100%;
    height: 100%;
    overflow: hidden;
    outline: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: none;
    align-items: center;
    justify-content: center;
  }
  
  .b4-modal.show {
    display: flex;
  }
  
  .b4-modal-dialog {
    position: relative;
    width: auto;
    max-width: 500px;
    margin: 1.75rem auto;
    pointer-events: none;
  }
  
  .b4-modal-content {
    position: relative;
    display: flex;
    flex-direction: column;
    width: 100%;
    pointer-events: auto;
    background-color: var(--b4-white);
    background-clip: padding-box;
    border: 1px solid rgba(0, 0, 0, 0.2);
    border-radius: var(--b4-rounded-lg);
    outline: 0;
    box-shadow: var(--b4-shadow-lg);
  }
  
  .b4-modal-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    padding: 1rem;
    border-bottom: 1px solid #dee2e6;
    border-top-left-radius: calc(0.3rem - 1px);
    border-top-right-radius: calc(0.3rem - 1px);
  }
  
  .b4-modal-title {
    margin-bottom: 0;
    line-height: 1.5;
  }
  
  .b4-modal-body {
    position: relative;
    flex: 1 1 auto;
    padding: 1rem;
  }
  
  .b4-modal-footer {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: flex-end;
    padding: 0.75rem;
    border-top: 1px solid #dee2e6;
    border-bottom-right-radius: calc(0.3rem - 1px);
    border-bottom-left-radius: calc(0.3rem - 1px);
  }
  
  .b4-modal-footer > * {
    margin: 0.25rem;
  }
  
  .b4-btn-close {
    background: transparent;
    border: 0;
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1;
    color: #000;
    text-shadow: 0 1px 0 #fff;
    opacity: 0.5;
    cursor: pointer;
    padding: 0;
  }
  
  /* ===== Navbar ===== */
  .navbar-fixed {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    z-index: var(--b4-z-fixed);
    background-color: var(--b4-white);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  }
  
  .desktop-menu a {
    text-decoration: none;
    transition: color 0.3s ease;
  }
  
  /* Dark mode toggle */
  .dark-mode-toggle {
    margin-left: 1rem;
  }
  
  .toggle-switch {
    position: relative;
    display: inline-block;
    width: 40px;
    height: 24px;
    margin: 0 10px;
  }
  
  .toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
  }
  
  .toggle-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
  }
  
  .toggle-slider:before {
    position: absolute;
    content: "";
    height: 16px;
    width: 16px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
  }
  
  input:checked + .toggle-slider {
    background-color: var(--b4-primary);
  }
  
  input:checked + .toggle-slider:before {
    transform: translateX(16px);
  }
  
  /* Mobile Menu */
  .mobile-menu {
    display: none;
  }
  
  .mobile-menu-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--b4-dark);
  }
  
  .mobile-menu-items {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    width: 250px;
    background-color: var(--b4-white);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    padding: 1rem;
    z-index: 1000;
    border-radius: var(--b4-rounded);
  }
  
  .mobile-menu-items.show {
    display: block;
  }
  
  .mobile-menu-items a {
    display: block;
    padding: 0.5rem 0;
    color: var(--b4-dark);
    text-decoration: none;
    transition: color 0.3s ease;
  }
  
  .mobile-menu-items a:hover {
    color: var(--b4-primary);
  }
  
  @media (max-width: 768px) {
    .desktop-menu {
      display: none;
    }
    
    .mobile-menu {
      display: block;
    }
  }
  
  /* ===== Code Examples & Editor ===== */
  .code-example {
    border: 1px solid #dee2e6;
    border-radius: var(--b4-rounded);
    overflow: hidden;
    margin-bottom: 1.5rem;
  }
  
  .code-example-header {
    background-color: #f8f9fa;
    padding: 0.75rem 1rem;
    border-bottom: 1px solid #dee2e6;
    font-weight: 500;
  }
  
  .code-example-preview {
    padding: 1.5rem;
    border-bottom: 1px solid #dee2e6;
  }
  
  .code-example-body {
    background-color: #2d2d2d;
    color: #f8f9fa;
    margin: 0;
    padding: 0;
  }
  
  .code-example-body pre {
    margin: 0;
    background-color: transparent;
  }
  
  .code-example-body code {
    font-family: var(--b4-font-mono);
    color: #f8f9fa;
    padding: 1rem;
    display: block;
    overflow-x: auto;
  }
  
  .code-editor {
    width: 100%;
    height: 400px;
    border: 1px solid #dee2e6;
    border-radius: var(--b4-rounded);
    font-family: var(--b4-font-mono);
    font-size: 0.875rem;
    padding: 1rem;
    resize: vertical;
  }
  
  .preview-area {
    width: 100%;
    height: 400px;
    border: 1px solid #dee2e6;
    border-radius: var(--b4-rounded);
    padding: 1rem;
    overflow: auto;
    background-color: white;
  }
  
  /* ===== Section Styles ===== */
  .section-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 0.5rem;
  }
  
  .section-title:after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background-color: var(--b4-primary);
    border-radius: 2px;
  }
  
  /* ===== Grid Demo Boxes ===== */
  .grid-demo-box {
    padding: 1.5rem;
    background-color: rgba(63, 106, 216, 0.1);
    border: 1px solid rgba(63, 106, 216, 0.2);
    border-radius: var(--b4-rounded);
    text-align: center;
    margin-bottom: 1rem;
  }
  
  /* ===== Color Boxes ===== */
  .color-box {
    height: 100px;
    border-radius: var(--b4-rounded);
    margin-bottom: 0.5rem;
    position: relative;
    overflow: hidden;
    box-shadow: var(--b4-shadow-sm);
  }
  
  .color-info {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 0.5rem;
    font-size: 0.875rem;
  }
  
  /* ===== Spacing Demo ===== */
  .spacing-demo {
    background-color: rgba(63, 106, 216, 0.1);
    border: 1px solid rgba(63, 106, 216, 0.2);
    padding: 0.75rem;
    border-radius: var(--b4-rounded);
  }
  
  /* ===== Hero Section ===== */
  .scroll-indicator {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    text-align: center;
    animation: bounce 2s infinite;
  }
  
  @keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
      transform: translateY(0) translateX(-50%);
    }
    40% {
      transform: translateY(-20px) translateX(-50%);
    }
    60% {
      transform: translateY(-10px) translateX(-50%);
    }
  }
  
  /* ===== Component Animations ===== */
  .component-animate {
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .component-animate:hover {
    transform: translateY(-5px);
    box-shadow: var(--b4-shadow);
  }
  
  /* ===== Grid Interactive Demo ===== */
  .grid-interactive [draggable="true"] {
    cursor: grab;
  }
  
  .grid-interactive [draggable="true"]:active {
    cursor: grabbing;
  }
  
  /* ===== Dark Mode ===== */
  .dark-mode {
    color: #f8f9fa;
    background-color: #212529;
  }
  
  .dark-mode .navbar-fixed {
    background-color: #343a40;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
  }
  
  .dark-mode .desktop-menu a, 
  .dark-mode .mobile-menu-btn {
    color: #f8f9fa;
  }
  
  .dark-mode .b4-card {
    background-color: #343a40;
    border-color: #495057;
  }
  
  .dark-mode .b4-card-header,
  .dark-mode .b4-card-footer {
    background-color: rgba(255, 255, 255, 0.05);
    border-color: #495057;
  }
  
  .dark-mode .b4-bg-light {
    background-color: #343a40 !important;
  }
  
  .dark-mode .b4-text-dark {
    color: #f8f9fa !important;
  }
  
  .dark-mode .code-example {
    border-color: #495057;
  }
  
  .dark-mode .code-example-header {
    background-color: #343a40;
    border-color: #495057;
  }
  
  .dark-mode .preview-area,
  .dark-mode .code-editor {
    background-color: #2d2d2d;
    color: #f8f9fa;
    border-color: #495057;
  }
  
  .dark-mode .grid-demo-box {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.2);
  }
  
  .dark-mode .b4-btn-outline-primary {
    color: #7fa4f7;
    border-color: #7fa4f7;
  }
  
  .dark-mode .b4-btn-outline-primary:hover {
    color: #212529;
    background-color: #7fa4f7;
  }
  
  /* ===== Hover Effects ===== */
  .hover\:b4-text-primary:hover {
    color: var(--b4-primary);
  }
  
  .hover\:b4-bg-primary:hover {
    background-color: var(--b4-primary);
  }
  
  /* ===== Media Query Utilities ===== */
  @media (min-width: 576px) {
    .b4-mt-sm-0 { margin-top: 0; }
    .b4-text-sm-left { text-align: left; }
    /* Add more SM utilities as needed */
  }
  
  @media (min-width: 768px) {
    .b4-mt-md-0 { margin-top: 0; }
    .b4-mb-md-0 { margin-bottom: 0; }
    .b4-text-md-left { text-align: left; }
    /* Add more MD utilities as needed */
  }
  
  @media (min-width: 992px) {
    .b4-mt-lg-0 { margin-top: 0; }
    .b4-text-lg-left { text-align: left; }
    /* Add more LG utilities as needed */
  }