/* ===================================================
   Global Reset & Base Styles
=================================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
html, body {
  font-family: 'Montserrat', sans-serif;
  background-color: #fff;
  color: #333;
  scroll-behavior: smooth;
}
a {
  text-decoration: none;
  color: inherit;
}

/* ===================================================
   Header & Navigation
=================================================== */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  padding: 10px 30px;
  background: rgba(255,255,255,0.95);
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  z-index: 100;
}
.logo img {
  max-width: 80px;
  height: auto;
}
header nav {
  display: flex;
  gap: 30px;
  flex-wrap: nowrap; /* 保持一行显示 */
}
header nav a {
  font-weight: 700;
  font-size: 1rem;
  color: #013220;
  transition: color 0.3s;
  position: relative;
  overflow: hidden;
  padding-bottom: 4px; /* 为下划线留出4px空间 */
}
header nav a:hover {
  color: #028A0F;
}
header nav a::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px; /* 下划线厚度 */
  background-color: #028A0F;
  transform: scaleX(0);
  transform-origin: var(--origin, left);
  transition: transform 0.3s ease;
}
header nav a:hover::after {
  transform: scaleX(1);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.8rem;
  color: #013220;
  cursor: pointer;
}

/* ===================================================
   Hero Section
=================================================== */
.hero {
  padding: 120px 20px 50px;
  background: #fff;
  margin-top: 60px; /* 防止固定导航重叠 */
}
.hero-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1200px;
  margin: 0 auto;
  gap: 20px;
}
.hero-left {
  flex: 1;
  text-align: left;
  max-width: 500px;
}
.hero-left h1 {
  margin-bottom: 20px;
  color: #013220;
}
.hero-left h1 .stable,
.hero-left h1 .inventory {
  display: block;
  text-align: left;
}
.hero-left h1 .stable {
  font-size: 60px;
}
.hero-left h1 .inventory {
  font-size: 40px;
}
.hero-left p {
  font-size: 1.8rem;
  margin-bottom: 20px;
  color: #013220;
  font-weight: 700;
}
.hero-left p span {
  display: block;
  white-space: nowrap;
}
.hero-contact {
  margin-top: 20px;
}
.contact-label {
  font-size: 12px;
  color: #013220;
  margin-bottom: 4px;
}
.hero-emails {
  font-size: 12px;
  color: #013220;
  margin-bottom: 4px;
  line-height: 1.2;
}
.contact-instructions {
  font-size: 12px !important;
  color: #333;
  margin-bottom: 8px;
  line-height: 1.2;
}
.hero-contact .hero-btn {
  display: inline-block;
  padding: 12px 30px;
  background: #028A0F;
  color: #fff;
  border-radius: 5px;
  font-weight: 700;
  transition: background 0.3s;
}
.hero-contact .hero-btn:hover {
  background: #026c0f;
}
.hero-right {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}
.hero-image {
  position: relative;
  width: 800px;
  height: 600px;
  overflow: hidden;
}
.hero-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.gradient-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(to right, rgba(255,255,255,0), rgba(255,255,255,0.2));
  pointer-events: none;
}

/* ===================================================
   Advantages Section
=================================================== */
.advantages {
  padding: 50px 50px;
  background: #f9f9f9;
  text-align: center;
}
.advantages .container {
  max-width: 1200px;
  margin: 0 auto;
}
.advantages h2 {
  font-size: 2.5rem;
  color: #013220;
  margin-bottom: 20px;
}
.advantages-grid {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 30px;
}
.advantage-item {
  background: #fff;
  padding: 20px;
  flex: 1;
  min-width: 250px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  border-radius: 5px;
  transition: transform 0.3s;
}
.advantage-item:hover {
  transform: translateY(-5px);
}
.advantage-item h3 {
  font-size: 1.5rem;
  margin-bottom: 10px;
  color: #013220;
}
.advantage-item p {
  font-size: 1rem;
  color: #333;
}

/* ===================================================
   Accordion Section: Silica Fume Applications
=================================================== */
.accordion {
  padding: 50px 50px;
  background: #f9f9f9;
  text-align: center;
}
.accordion .container {
  max-width: 1200px;
  margin: 0 auto;
}
.accordion h2 {
  font-size: 2.5rem;
  color: #013220;
  margin-bottom: 20px;
}
.accordion details {
  border: 1px solid #ddd;
  border-radius: 5px;
  margin-bottom: 10px;
  background: #fff;
  overflow: hidden;
  text-align: left;
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
}
.accordion summary {
  font-size: 1.5rem;
  font-weight: 700;
  color: #013220;
  padding: 10px;
  cursor: pointer;
  list-style: none;
  background: #f9f9f9;
  position: relative;
  padding-right: 30px;
}
.accordion summary::after {
  content: ">";
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  transition: transform 0.3s;
}
.accordion details[open] summary::after {
  content: "v";
}
.accordion details ul {
  list-style: disc inside;
  padding: 10px 20px;
  margin: 0;
}
.accordion details ul li {
  margin-bottom: 10px;
  font-size: 1rem;
  color: #333;
  line-height: 1.5;
}
.accordion details ul li strong {
  color: #013220;
}

/* ===================================================
   Footer
=================================================== */
footer {
  padding: 30px 50px;
  background: #fff;
  box-shadow: 0 -2px 5px rgba(0,0,0,0.1);
  margin-top: 50px;
}
.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 30px;
}
.footer-left {
  flex: 1;
  text-align: center;
}
.footer-title {
  font-size: 1.4rem;
  color: #013220;
  margin-bottom: 10px;
  font-weight: 700;
}
.footer-nav {
  display: flex;
  justify-content: center;
  gap: 50px;
}
.nav-column {
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.nav-column a {
  font-size: 1.1rem;
  color: #013220;
  transition: color 0.3s;
}
.nav-column a:hover {
  color: #028A0F;
}
.footer-right {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
}
.footer-contact {
  max-width: 400px;
  text-align: left;
}
.contact-title {
  font-size: 1.4rem;
  color: #013220;
  font-weight: 700;
  margin-bottom: 10px;
}
.footer-emails-line {
  font-size: 14px;
  color: #013220;
  margin-bottom: 8px;
  display: flex;
  gap: 20px;
}
.footer-emails-line span {
  white-space: nowrap;
}
.contact-instructions {
  font-size: 14px;
  color: #333;
  margin-bottom: 12px;
  line-height: 1.2;
}
.footer-form {
  display: flex;
  align-items: center;
  gap: 10px;
}
.ipt {
  padding: 8px 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
  font-size: 1.1rem;
  width: 250px;
}
.footer-form button {
  padding: 8px 20px;
  background: #028A0F;
  color: #fff;
  border: none;
  border-radius: 5px;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background 0.3s;
}
.footer-form button:hover {
  background: #026c0f;
}
/* ===================================================
   Product Aliases Section
=================================================== */
#product-aliases {
  padding: 50px 50px;
  background: #fff;
  text-align: center;
}

#product-aliases .container {
  max-width: 1200px;
  margin: 0 auto;
}

#product-aliases h2 {
  font-size: 2.5rem;
  color: #013220;
  margin-bottom: 20px;
}

#product-aliases p {
  font-size: 1.1rem;
  color: #333;
  margin-bottom: 20px;
}

#product-aliases ul {
  list-style: disc inside;
  padding: 0 20px;
  margin: 0 auto;
  max-width: 800px;
  text-align: left;
}

#product-aliases ul li {
  font-size: 1rem;
  color: #333;
  line-height: 1.6;
  margin-bottom: 10px;
}

#product-aliases ul li strong {
  color: #013220;
}
/* ===================================================
   Two Lines Intro Text for Product Aliases Section
=================================================== */
.two-lines p {
  display: block;
  max-width: 600px;      /* 固定最大宽度 */
  margin: 0 auto;        /* 居中显示 */
  white-space: nowrap;   /* 防止换行 */
  text-align: left;
  font-size: 1.1rem;
  color: #333;
  line-height: 1.5;
}

/* 给第一行文字增加一个 tab 缩进 */

/* 为了在屏幕较小时允许自动换行，可使用媒体查询进行调整 */
@media (max-width: 640px) {
  .two-lines p {
    white-space: normal;
    max-width: 90%;
  }
}

/* ===================================================
   Responsive Adjustments
=================================================== */
@media (max-width: 1200px) {
  header nav a {
    font-size: 0.9rem;
  }
  header nav {
    gap: 20px;
  }
  /* 当屏幕宽度小于或等于1200px时，部分页面（如Sustainability页面）可能有独立样式，此处不覆盖 */
}
@media (max-width: 800px) {
  header {
    padding: 10px 30px;
  }
  header nav {
    display: none;
  }
  .nav-toggle {
    display: block;
  }
  header.active nav {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: rgba(255,255,255,0.95);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    padding: 10px 0;
    gap: 10px;
  }
  header.active nav a {
    padding: 10px 20px;
  }
  .hero-container {
    flex-direction: column;
    text-align: center;
  }
  .hero-left, .hero-right {
    width: 100%;
  }
  .hero-left h1 {
    font-size: 2.5rem;
  }
  .hero-left p,
  .contact-label,
  .hero-emails,
  .contact-instructions {
    font-size: 12px;
  }
  .hero-contact .hero-btn {
    font-size: 1rem;
    padding: 10px 25px;
  }
  .advantages-grid {
    flex-direction: column;
    gap: 20px;
  }
  .footer-container {
    flex-direction: column;
    text-align: center;
  }
  .footer-left, .footer-right {
    width: 100%;
    text-align: center;
  }
  .footer-nav {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
  }
  .footer-form .ipt {
    width: 100%;
    max-width: 300px;
  }
}