/* ═══════════════════════════════════════════
   LAYOUT SYSTEM
   ═══════════════════════════════════════════ */

/* ─── Breakpoints ───
   sm:  640px
   md:  768px
   lg:  1024px
   xl:  1280px
   2xl: 1536px   */

/* ─── App Shell ─── */
.app-shell {
  display: grid;
  grid-template-areas:
    "sidebar header"
    "sidebar main";
  grid-template-columns: var(--sidebar-width) 1fr;
  grid-template-rows: var(--header-height) 1fr;
  min-height: 100vh;
}

.app-shell__header {
  grid-area: header;
  position: sticky;
  top: 0;
  z-index: var(--z-header);
}

.app-shell__sidebar {
  grid-area: sidebar;
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  z-index: var(--z-sidebar);
}

.app-shell__main {
  grid-area: main;
  padding: var(--page-padding);
  overflow-y: auto;
}

/* ─── Container ─── */
.container {
  width: 100%;
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.container--narrow {
  max-width: var(--content-narrow);
}

.container--full {
  max-width: none;
  padding: 0;
}

/* ─── Page Layout ─── */
.page {
  max-width: var(--content-max-width);
  margin: 0 auto;
  width: 100%;
}

.page__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-8);
  flex-wrap: wrap;
}

.page__title {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  color: var(--color-text);
  letter-spacing: var(--tracking-tight);
}

.page__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
}

.page__section {
  margin-bottom: var(--space-8);
}

.page__section-title {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

.page__section-desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
}

/* ─── Content Section ─── */
.section {
  margin-bottom: var(--space-8);
}

.section__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-4);
}

.section__title {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  color: var(--color-text);
}

/* ─── Grid ─── */
.grid {
  display: grid;
  gap: var(--space-4);
}

.grid--2    { grid-template-columns: repeat(2, 1fr); }
.grid--3    { grid-template-columns: repeat(3, 1fr); }
.grid--4    { grid-template-columns: repeat(4, 1fr); }
.grid--auto { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
.grid--compact  { gap: var(--space-3); }
.grid--spacious { gap: var(--space-6); }

/* ─── Flex ─── */
.flex     { display: flex; }
.flex--col      { flex-direction: column; }
.flex--row      { flex-direction: row; }
.flex--wrap     { flex-wrap: wrap; }
.flex--nowrap   { flex-wrap: nowrap; }
.flex--center   { align-items: center; justify-content: center; }
.flex--between  { justify-content: space-between; }
.flex--around   { justify-content: space-around; }
.flex--evenly   { justify-content: space-evenly; }
.flex--gap      { gap: var(--space-4); }
.flex--gap-sm   { gap: var(--space-2); }
.flex--gap-lg   { gap: var(--space-6); }
.flex--1    { flex: 1; }
.flex--auto { flex: 1 1 auto; }
.flex--none { flex: none; }
.items-center    { align-items: center; }
.items-start     { align-items: flex-start; }
.items-end       { align-items: flex-end; }
.self-center     { align-self: center; }
.self-start      { align-self: flex-start; }
.self-end        { align-self: flex-end; }
.justify-center  { justify-content: center; }
.justify-start   { justify-content: flex-start; }
.justify-end     { justify-content: flex-end; }

/* ─── Stack (vertical spacing) ─── */
.stack { display: flex; flex-direction: column; }
.stack--sm  { gap: var(--space-2); }
.stack--md  { gap: var(--space-4); }
.stack--lg  { gap: var(--space-6); }
.stack--xl  { gap: var(--space-8); }

/* ─── Inline ─── */
.inline {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-2);
}

/* ─── Spacer ─── */
.spacer { flex: 1; }
.spacer--h { width: 0; height: 1px; margin: var(--space-4) 0; }

/* ─── Responsive ─── */
@media (max-width: 640px) {
  .app-shell {
    grid-template-areas:
      "header"
      "main";
    grid-template-columns: 1fr;
  }

  .app-shell__sidebar {
    transform: translateX(-100%);
    transition: transform var(--transition-fast);
  }

  .app-shell__sidebar--open {
    transform: translateX(0);
  }

  .app-shell__main {
    padding: var(--page-padding-mobile);
  }

  .page__header {
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-3);
    margin-bottom: var(--space-6);
  }

  .page__actions {
    justify-content: stretch;
  }

  .page__actions .btn {
    flex: 1;
  }

  .grid--2,
  .grid--3,
  .grid--4 {
    grid-template-columns: 1fr;
  }

  .hidden-mobile { display: none !important; }
}

@media (min-width: 641px) and (max-width: 1024px) {
  .grid--3 { grid-template-columns: repeat(2, 1fr); }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .page__title {
    font-size: var(--text-xl);
  }
}

@media (min-width: 1025px) {
  .hidden-desktop { display: none !important; }
}