/* ============================================
   Layer 2: 模块容器 — Layout
   
   定义页面的骨骼结构：
   容器宽度、网格系统、Section 间距
   子元素放入容器后自动继承正确的布局
   ============================================ */

/* === 容器 === */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.container-narrow {
  max-width: var(--container-narrow);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.container-fluid {
  width: 100%;
  padding: 0 var(--container-padding);
}

/* === Section 间距 === */
.section {
  padding: 40px 0;
  scroll-margin-top: 80px;
}

@media (min-width: 768px) {
  .section {
    padding: 96px 0;
  }
}

.section-sm {
  padding: var(--space-2xl) 0;
}

.section-lg {
  padding: calc(var(--space-section) * 1.5) 0;
}

.section-hero {
  padding: var(--space-3xl) 0 var(--space-section) 0;
}

/* === Grid 布局 === */
.grid {
  display: grid;
  gap: var(--space-lg);
}

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

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

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

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

/* 响应式 Grid */
@media (max-width: 1200px) {
  .grid-cols-4 {
    grid-template-columns: repeat(3, 1fr);
  }
  .grid-cols-5 {
    grid-template-columns: repeat(4, 1fr);
  }
}

@media (max-width: 1024px) {
  .grid-cols-3,
  .grid-cols-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid-cols-5 {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 768px) {
  .grid-cols-2,
  .grid-cols-3,
  .grid-cols-4,
  .grid-cols-5 {
    grid-template-columns: 1fr;
  }
  
  .section {
    padding: var(--space-section-mobile) 0;
  }
  
  .container {
    padding: 0 var(--container-padding-mobile);
  }
}

/* === Flex 布局 === */
.flex {
  display: flex;
}

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

.flex-row {
  display: flex;
  flex-direction: row;
}

.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

.flex-between {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.flex-start {
  display: flex;
  align-items: center;
  justify-content: flex-start;
}

.flex-end {
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.flex-wrap {
  flex-wrap: wrap;
}

.flex-nowrap {
  flex-wrap: nowrap;
}

.flex-1 {
  flex: 1;
}

.flex-auto {
  flex: auto;
}

.flex-none {
  flex: none;
}

/* === 对齐 === */
.items-start {
  align-items: flex-start;
}

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

.items-end {
  align-items: flex-end;
}

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

.justify-start {
  justify-content: flex-start;
}

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

.justify-end {
  justify-content: flex-end;
}

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

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

/* === 间距 === */
.gap-xs {
  gap: var(--space-xs);
}

.gap-sm {
  gap: var(--space-sm);
}

.gap-md {
  gap: var(--space-md);
}

.gap-base {
  gap: var(--space-base);
}

.gap-lg {
  gap: var(--space-lg);
}

.gap-xl {
  gap: var(--space-xl);
}

/* === Header 固定 === */
.header-fixed {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-fixed);
  background: var(--color-bg-white);
  box-shadow: var(--shadow-sm);
}

/* === 侧边浮动 === */
.sidebar-float {
  position: fixed;
  right: var(--space-lg);
  bottom: var(--space-xl);
  z-index: var(--z-sticky);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

@media (max-width: 768px) {
  .sidebar-float {
    right: var(--space-sm);
    bottom: var(--space-lg);
  }
}

.page-main {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  padding-top: 64px;
}