/* Global Reset & Variables */
:root {
  --primary-color: #ff5f00; /* 橙色主色调 */
  --text-color: #333;
  --text-secondary: #666;
  --bg-light: #fff9f5; /* 浅橙色背景 */
  --white: #fff;
  --border-radius: 12px;
  --container-width: 1200px;
}

body {
  margin: 0;
  padding: 0;
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  background-color: var(--white);
  color: var(--text-color);
  background: linear-gradient(
    180deg,
    rgba(253, 113, 11, 0.1) 0%,
    rgba(253, 113, 11, 0) 20%
  );
}

ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

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

.container {
  width: var(--container-width);
  margin: 0 auto;
  padding: 0 20px;
  box-sizing: border-box;
}

/* Utilities */
.flex {
  display: flex;
}
.flex-center {
  display: flex;
  justify-content: center;
  align-items: center;
}
.flex-between {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.flex-col {
  display: flex;
  flex-direction: column;
}
.text-center {
  text-align: center;
}
.mt-20 {
  margin-top: 20px;
}
.mb-20 {
  margin-bottom: 20px;
}
.mt-40 {
  margin-top: 40px;
}
.mb-40 {
  margin-bottom: 40px;
}
.mb-60 {
  margin-bottom: 60px;
}

/* Header */
.header {
  height: 60px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: #fffcf9;
}

.nav-links {
  display: flex;
  gap: 40px;
}

.nav-item {
  font-size: 16px;
  cursor: pointer;
  position: relative;
  padding: 10px 0;
}

.nav-item.active,
.nav-item:hover {
  color: var(--primary-color);
  font-weight: bold;
}

.nav-item.active::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--primary-color);
  border-radius: 2px;
}

/* Footer */
.footer {
  background: #f8f8f8;
  padding: 40px 0;
  text-align: center;
  color: #999;
  font-size: 14px;
}

/* Floating Sidebar */
.fixed-buttons {
  position: fixed;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.fixed-btn {
  width: 60px;
  height: 70px;
  background: white;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 12px;
  color: #666;
  transition: all 0.3s;
}

.fixed-btn:hover {
    background: var(--primary-color);
    color: white;
}

.fixed-btn:hover .icon-normal {
    opacity: 0;
}

.fixed-btn:hover .icon-hover {
    opacity: 1;
}

.fixed-icon-container {
    width: 24px;
    height: 24px;
    position: relative;
    margin-bottom: 5px;
}

.fixed-icon-container img {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    transition: opacity 0.3s;
}

.icon-normal {
    opacity: 1;
}

.icon-hover {
    opacity: 0;
}