/* 
 * Premium Education Investment Platform - Layout System
 * Grid, Container, and Page Structure for Institutional Credibility
 */

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-secondary);
  font-weight: var(--font-weight-regular);
  font-size: var(--font-size-body-medium);
  line-height: 1.6;
  color: var(--brand-primary-dark);
  background-color: var(--brand-white);
}

a {
  text-decoration: none;
  color: inherit;
}

ul, ol {
  list-style: none;
}

img {
  max-width: 100%;
  height: auto;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

/* Grid System */
.grid {
  display: grid;
  gap: var(--spacing-md);
}

.grid-cols-1 {
  grid-template-columns: 1fr;
}

.grid-cols-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-cols-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid-cols-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.grid-cols-5 {
  grid-template-columns: repeat(5, minmax(0, 1fr));
}

/* Responsive grid variants (mobile-first: base class is the small-screen layout) */
@media (min-width: 576px) {
  .sm\:grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sm\:grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .sm\:grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

@media (min-width: 768px) {
  .md\:grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .md\:grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .md\:grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .md\:grid-cols-5 { grid-template-columns: repeat(5, minmax(0, 1fr)); }
  .md\:col-span-2 { grid-column: span 2; }
}

@media (min-width: 992px) {
  .lg\:grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .lg\:grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .lg\:grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .lg\:grid-cols-5 { grid-template-columns: repeat(5, minmax(0, 1fr)); }
}

/* Flexbox */
.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.justify-center {
  justify-content: center;
}

.justify-between {
  justify-content: space-between;
}

.items-center {
  align-items: center;
}

.text-center {
  text-align: center;
}

/* Spacing Utilities */
.mt-0 { margin-top: 0; }
.mt-xs { margin-top: var(--spacing-xs); }
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-xs { margin-bottom: var(--spacing-xs); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.pt-0 { padding-top: 0; }
.pt-xs { padding-top: var(--spacing-xs); }
.pt-sm { padding-top: var(--spacing-sm); }
.pt-md { padding-top: var(--spacing-md); }
.pt-lg { padding-top: var(--spacing-lg); }
.pt-xl { padding-top: var(--spacing-xl); }

.pb-0 { padding-bottom: 0; }
.pb-xs { padding-bottom: var(--spacing-xs); }
.pb-sm { padding-bottom: var(--spacing-sm); }
.pb-md { padding-bottom: var(--spacing-md); }
.pb-lg { padding-bottom: var(--spacing-lg); }
.pb-xl { padding-bottom: var(--spacing-xl); }

/* Responsive Utilities */
@media (max-width: 576px) {
  .hide-mobile {
    display: none !important;
  }
  
  .grid-cols-2,
  .grid-cols-3,
  .grid-cols-4 {
    grid-template-columns: 1fr;
  }
}

@media (min-width: 576px) and (max-width: 992px) {
  .hide-tablet {
    display: none !important;
  }
}

/* Accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--brand-primary-dark);
  color: white;
  padding: 8px;
  text-decoration: none;
  border-radius: var(--border-radius-sm);
  z-index: 1000;
}

.skip-link:focus {
  top: 6px;
}