/* ============================================================
   base.css — 全局基础样式与排版
   包含 CSS Reset、字体导入、排版规范、工具类
   ============================================================ */

/* ----------------------------------------------------------
   Google Fonts — Inter (300/400/500/600/700)
   ---------------------------------------------------------- */
/* 字体使用本机系统栈，避免外部字体请求阻塞首屏。 */

/* ----------------------------------------------------------
   现代 CSS Reset
   ---------------------------------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* 移除列表默认样式 */
ul,
ol {
  list-style: none;
}

/* 重置链接样式 */
a {
  text-decoration: none;
  color: inherit;
}

/* 图片默认行为 */
img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
}

/* 表单元素继承字体 */
input,
button,
textarea,
select {
  font: inherit;
}

/* 移除按钮默认样式 */
button {
  cursor: pointer;
  border: none;
  background: none;
}

/* 移除文本区域缩放限制 */
textarea {
  resize: vertical;
}

/* 表格边框合并 */
table {
  border-collapse: collapse;
  border-spacing: 0;
}

/* ----------------------------------------------------------
   HTML 根元素
   ---------------------------------------------------------- */
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  -moz-text-size-adjust: 100%;
  text-size-adjust: 100%;
  font-size: 16px;
}

/* ----------------------------------------------------------
   Body 基础样式
   ---------------------------------------------------------- */
body {
  font-family: var(--font-cn);
  background-color: var(--color-pearl-white);
  color: var(--color-graphite-black);
  line-height: var(--leading-relaxed);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
  min-height: 100vh;
}

/* ----------------------------------------------------------
   标题排版 — 使用英文字体栈
   ---------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-en);
  letter-spacing: var(--tracking-wide);
  line-height: var(--leading-tight);
  color: var(--color-graphite-black);
}

h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: var(--weight-bold);
}

h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: var(--weight-bold);
}

h3 {
  font-size: clamp(1.25rem, 2.5vw, 1.75rem);
  font-weight: var(--weight-semibold);
}

h4 {
  font-size: clamp(1.1rem, 2vw, 1.35rem);
  font-weight: var(--weight-semibold);
}

/* ----------------------------------------------------------
   正文排版
   ---------------------------------------------------------- */
p {
  margin-bottom: var(--space-4);
  line-height: var(--leading-relaxed);
}

p:last-child {
  margin-bottom: 0;
}

strong, b {
  font-weight: var(--weight-semibold);
}

small {
  font-size: var(--text-base);
}

/* ----------------------------------------------------------
   选中文本样式
   ---------------------------------------------------------- */
::selection {
  background-color: var(--color-gold-light);
  color: var(--color-graphite-black);
}

::-moz-selection {
  background-color: var(--color-gold-light);
  color: var(--color-graphite-black);
}

/* ----------------------------------------------------------
   滚动条美化（WebKit 浏览器）
   ---------------------------------------------------------- */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--color-platinum-gray);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-graphite-black);
}

/* ----------------------------------------------------------
   Section 通用布局
   ---------------------------------------------------------- */
.section {
  padding: var(--space-24) var(--space-6);
  max-width: var(--max-width);
  margin: 0 auto;
}

/* ----------------------------------------------------------
   Container 容器
   ---------------------------------------------------------- */
.container {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

/* ----------------------------------------------------------
   渐入动画系统
   ---------------------------------------------------------- */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 延迟序列 — 用于卡片依次出现 */
.fade-in-delay-1 {
  transition-delay: 0.1s;
}

.fade-in-delay-2 {
  transition-delay: 0.2s;
}

.fade-in-delay-3 {
  transition-delay: 0.3s;
}

.fade-in-delay-4 {
  transition-delay: 0.4s;
}

/* 从左侧渐入 */
.fade-in-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-left.visible {
  opacity: 1;
  transform: translateX(0);
}

/* 从右侧渐入 */
.fade-in-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* 缩放渐入 */
.fade-in-scale {
  opacity: 0;
  transform: scale(0.95);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-scale.visible {
  opacity: 1;
  transform: scale(1);
}

/* ----------------------------------------------------------
   辅助工具类
   ---------------------------------------------------------- */

/* 文本对齐 */
.text-center {
  text-align: center;
}

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

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

/* 金色强调色文本 */
.text-gold {
  color: var(--color-champagne-gold);
}

/* 灰色辅助文本 */
.text-muted {
  color: var(--color-platinum-gray);
}

/* 副标题样式 */
.section-subtitle {
  font-size: var(--text-md);
  color: var(--color-champagne-gold);
  font-weight: var(--weight-semibold);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: var(--space-3);
}

/* 段落描述文本 */
.section-desc {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
  line-height: var(--leading-relaxed);
}

/* 分隔线 */
.divider {
  width: 48px;
  height: 2px;
  background: var(--color-champagne-gold);
  margin: var(--space-6) auto;
  border: none;
}

/* 视觉隐藏（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-width: 0;
}

/* ----------------------------------------------------------
   通用板块头部样式 (Pillars Header)
   ---------------------------------------------------------- */
.pillars-header {
  text-align: center;
  margin-bottom: var(--space-16);
}

.pillars-header .section-subtitle {
  font-size: var(--text-md);
  color: var(--color-champagne-gold);
  font-weight: var(--weight-semibold);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  margin-bottom: var(--space-3);
}

.pillars-header h2 {
  margin-bottom: var(--space-4);
}

.pillars-header p {
  font-size: var(--text-md);
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto;
  line-height: var(--leading-relaxed);
}

/* ----------------------------------------------------------
   FAQ Section (手风琴)
   ---------------------------------------------------------- */
.faq-section {
  background: var(--color-pure-white);
}

.faq-container {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.faq-item {
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.faq-item.active {
  border-color: var(--color-gold-border);
  box-shadow: var(--shadow-sm);
}

.faq-question {
  padding: var(--space-5) var(--space-6);
  width: 100%;
  border: 0;
  text-align: left;
  font: inherit;
  background: var(--color-pure-white);
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-base);
}

.faq-question:hover {
  background: var(--color-bg-hover);
}

.faq-title {
  font-size: var(--text-lg);
  font-weight: var(--weight-semibold);
  color: var(--color-graphite-black);
  padding-right: var(--space-4);
}

.faq-icon {
  width: 20px;
  height: 20px;
  position: relative;
  flex-shrink: 0;
  transition: transform var(--transition-base);
}

.faq-icon::before, .faq-icon::after {
  content: '';
  position: absolute;
  background: var(--color-champagne-gold);
  transition: transform var(--transition-base);
}

/* Horizontal line */
.faq-icon::before {
  top: 9px;
  left: 2px;
  width: 16px;
  height: 2px;
}

/* Vertical line */
.faq-icon::after {
  top: 2px;
  left: 9px;
  width: 2px;
  height: 16px;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

.faq-item.active .faq-icon::after {
  transform: rotate(90deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-cubic);
  background: var(--color-pearl-white);
}

.faq-answer-content {
  padding: var(--space-5) var(--space-6);
  font-size: var(--text-md);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  border-top: 1px solid var(--color-border-subtle);
}

/* ----------------------------------------------------------
   响应式断点
   ---------------------------------------------------------- */
@media (max-width: 768px) {
  .section {
    padding: var(--space-16) var(--space-5);
  }

  .container {
    padding: 0 var(--space-5);
  }

  .section-desc {
    font-size: var(--text-md);
  }
}

@media (max-width: 480px) {
  .section {
    padding: var(--space-12) var(--space-4);
  }

  .container {
    padding: 0 var(--space-4);
  }
}

/* ----------------------------------------------------------
   适应症与征兆卡片链接样式
   ---------------------------------------------------------- */
a.symptom-card,
a.indication-card {
  text-decoration: none;
  cursor: pointer;
  display: block;
}

a.symptom-card *,
a.indication-card * {
  text-align: left;
}