/* ============================================================
 * 全局基础样式 —— reset、排版、通用工具类
 * ============================================================ */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: var(--font-size-base);
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  /* 防止任意页面出现横向溢出，导致 sticky 头部/导航显得大小不一致；
     用 clip 而非 hidden，避免建立滚动容器影响 sticky 头部定位 */
  overflow-x: clip;
}

/* 主体内容区撑满，页脚沉底 */
.site-main {
  flex: 1 0 auto;
}

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

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
}

ul,
ol {
  list-style: none;
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

input,
select,
textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--color-heading);
  font-weight: 600;
  line-height: 1.35;
}

/* ---- 布局容器 ---- */
.container {
  width: 100%;
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ---- 区块 ---- */
.section {
  padding: var(--space-xl) 0;
}

.section--gray {
  background: var(--color-bg-gray);
}

.section__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-lg);
  gap: var(--space-md);
  flex-wrap: wrap;
}

.section__title {
  font-size: var(--fs-xl);
  position: relative;
  padding-left: 14px;
}

.section__title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 5px;
  height: 1.1em;
  background: var(--color-primary);
  border-radius: var(--radius-sm);
}

/* ---- 带图标的栏目标题：用图标徽章替代纯竖条，视觉更具体 ---- */
.section__title--icon {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding-left: 0;
}

.section__title--icon::before {
  display: none;
}

.section-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  flex-shrink: 0;
  border-radius: var(--radius-md);
  color: var(--color-primary);
  background: var(--color-primary-bg);
}

.section-icon svg {
  width: 22px;
  height: 22px;
}

/* 灰底区块内的图标徽章：加一点边框让其在浅灰上更清晰 */
.section--gray .section-icon {
  background: #fff;
  box-shadow: inset 0 0 0 1px var(--color-border);
}

.section__more {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.section__more:hover {
  color: var(--color-primary);
}

.section__more::after {
  content: " ›";
}

.section__intro {
  color: var(--color-text-secondary);
  font-size: var(--fs-md);
  line-height: 1.8;
  margin-bottom: var(--space-lg);
  max-width: 60em;
}

/* ---- 页面顶部横幅（内页通用） ---- */
.page-banner {
  background:
    linear-gradient(90deg, rgba(10, 26, 54, 0.78), rgba(10, 26, 54, 0.35)),
    url("../images/banner_small.jpg") center / cover no-repeat;
  color: #fff;
  padding: var(--space-2xl) 0;
}

.page-banner__title {
  color: #fff;
  font-size: var(--fs-2xl);
}

.page-banner__crumb {
  margin-top: var(--space-sm);
  font-size: var(--fs-sm);
  color: rgba(255, 255, 255, 0.85);
}

.page-banner__crumb a {
  color: rgba(255, 255, 255, 0.85);
}

.page-banner__crumb a:hover {
  color: #fff;
}

/* ---- 占位图（本阶段无真实图片，用渐变 + 纹理 + 图标水印占位） ---- */
.placeholder-img {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background:
    radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.12), transparent 55%),
    linear-gradient(135deg, var(--color-primary-light), var(--color-primary-dark));
  color: rgba(255, 255, 255, 0.95);
  font-size: var(--fs-sm);
  font-weight: 600;
  letter-spacing: 2px;
  text-align: center;
  overflow: hidden;
}

/* 细网点纹理，避免大面积纯色的“空占位”观感 */
.placeholder-img::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(255, 255, 255, 0.16) 1px, transparent 1.4px);
  background-size: 14px 14px;
  opacity: 0.6;
  pointer-events: none;
}

/* 右下角图标水印（由 data-icon 属性注入的 SVG 承载） */
.placeholder-img__watermark {
  position: absolute;
  right: -8px;
  bottom: -10px;
  width: 92px;
  height: 92px;
  opacity: 0.16;
  pointer-events: none;
  color: #fff;
}

.placeholder-img__watermark svg {
  width: 100%;
  height: 100%;
}

.placeholder-img__text {
  position: relative;
  z-index: 1;
  padding: 0 var(--space-md);
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.25);
}

.placeholder-img--gray {
  background:
    radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.28), transparent 55%),
    linear-gradient(135deg, #dce3ec, #aab7c7);
  color: #ffffff;
}

.placeholder-img--gray .placeholder-img__watermark {
  color: #ffffff;
  opacity: 0.28;
}

/* ---- 头像占位（首字圆形） ---- */
.avatar-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: #fff;
  font-weight: 600;
  flex-shrink: 0;
}

/* ---- 工具类 ---- */
.text-center { text-align: center; }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.hidden { display: none !important; }

/* 仅屏幕阅读器可见 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ---- 无障碍：跳过导航 ---- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-sm) var(--space-md);
  z-index: var(--z-toast);
}

.skip-link:focus {
  left: 0;
}

:focus-visible {
  outline: 2px solid var(--color-primary-light);
  outline-offset: 2px;
}