/* ========================================
   诺灏科技 KnowhowTech - 公共样式
   主题色: 黑 #0A0A0A | 科技红 #D6001C | 白 #FFFFFF
   辅助色: 深灰 #1F2937 | 浅灰 #F5F5F5
   ======================================== */

/* ---- 全局重置 ---- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  color: #FFFFFF;
  background-color: #0A0A0A;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

ul, ol {
  list-style: none;
}

a {
  text-decoration: none;
  color: inherit;
  transition: color 0.3s ease;
}

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

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

/* ---- 变量 ---- */
:root {
  --color-black: #0A0A0A;
  --color-red: #D6001C;
  --color-red-dark: #B00018;
  --color-white: #FFFFFF;
  --color-gray-dark: #1F2937;
  --color-gray-mid: #374151;
  --color-gray-light: #9CA3AF;
  --color-gray-bg: #F5F5F5;
  --color-border: rgba(255,255,255,0.1);
  --max-width: 1280px;
  --header-height: 72px;
}

/* ---- 布局容器 ---- */
.wrapper {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
}

.section-dark {
  background-color: var(--color-black);
}

.section-gray {
  background-color: #111111;
}

/* ---- 标题系统 ---- */
.section-title {
  font-size: 40px;
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-white);
  text-align: center;
  margin-bottom: 16px;
}

.section-title span {
  color: var(--color-red);
}

.section-subtitle {
  font-size: 18px;
  color: var(--color-gray-light);
  text-align: center;
  max-width: 640px;
  margin: 0 auto 60px;
  line-height: 1.6;
}

/* ---- 按钮系统 ---- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 36px;
  font-size: 16px;
  font-weight: 500;
  border-radius: 6px;
  transition: all 0.3s ease;
  cursor: pointer;
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--color-red);
  color: var(--color-white);
  border: 2px solid var(--color-red);
}

.btn-primary:hover {
  background-color: var(--color-red-dark);
  border-color: var(--color-red-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(214, 0, 28, 0.3);
}

.btn-outline {
  background-color: transparent;
  color: var(--color-white);
  border: 2px solid rgba(255,255,255,0.3);
}

.btn-outline:hover {
  border-color: var(--color-white);
  background-color: rgba(255,255,255,0.05);
}

.btn-white {
  background-color: var(--color-white);
  color: var(--color-black);
  border: 2px solid var(--color-white);
}

.btn-white:hover {
  background-color: var(--color-gray-bg);
  transform: translateY(-2px);
}

/* ---- 导航栏 ---- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  z-index: 1000;
  background: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border);
  transition: all 0.3s ease;
}

.header .wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-text {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-white);
  letter-spacing: 1px;
}

.logo-text span {
  color: var(--color-red);
}

.logo-sub {
  font-size: 11px;
  color: var(--color-gray-light);
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-top: -4px;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 36px;
}

.nav-menu a {
  font-size: 15px;
  color: rgba(255,255,255,0.7);
  font-weight: 400;
  position: relative;
  padding: 4px 0;
}

.nav-menu a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-red);
  transition: width 0.3s ease;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--color-white);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
  width: 100%;
}

.nav-cta {
  display: flex;
  align-items: center;
}

.nav-cta .btn {
  padding: 10px 24px;
  font-size: 14px;
}

.mobile-cta {
  display: none;
}

/* 移动端菜单按钮 */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
  cursor: pointer;
  z-index: 1001;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-white);
  transition: all 0.3s ease;
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ---- 页脚 ---- */
.footer {
  background-color: #050505;
  border-top: 1px solid var(--color-border);
}

.footer-main {
  padding: 80px 0 60px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 48px;
}

.footer-brand .logo-text {
  margin-bottom: 16px;
}

.footer-brand p {
  color: var(--color-gray-light);
  font-size: 14px;
  line-height: 1.8;
  max-width: 320px;
}

.footer-col h4 {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-white);
  margin-bottom: 20px;
}

.footer-col ul li {
  margin-bottom: 12px;
}

.footer-col ul li a {
  color: var(--color-gray-light);
  font-size: 14px;
  transition: color 0.3s ease;
}

.footer-col ul li a:hover {
  color: var(--color-red);
}

.footer-contact p {
  color: var(--color-gray-light);
  font-size: 14px;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.footer-contact .contact-icon {
  width: 20px;
  text-align: center;
  color: var(--color-red);
}

.footer-bottom {
  border-top: 1px solid var(--color-border);
  padding: 24px 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-bottom p,
.footer-bottom a {
  font-size: 13px;
  color: var(--color-gray-mid);
}

.footer-bottom a:hover {
  color: var(--color-gray-light);
}

/* ---- 通用卡片 ---- */
.card {
  background-color: var(--color-gray-dark);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  overflow: hidden;
  transition: all 0.3s ease;
}

.card:hover {
  border-color: rgba(214, 0, 28, 0.3);
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.3);
}

/* ---- 动画 ---- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.fade-in-up {
  animation: fadeInUp 0.8s ease forwards;
}

/* Scroll reveal 基础类 */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========================================
   响应式设计
   ======================================== */

/* 平板端 768px - 1023px */
@media (max-width: 1023px) {
  .section {
    padding: 70px 0;
  }

  .section-title {
    font-size: 32px;
  }

  .section-subtitle {
    font-size: 16px;
    margin-bottom: 48px;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 36px;
  }
}

/* 移动端 < 768px */
@media (max-width: 767px) {
  :root {
    --header-height: 64px;
  }

  .section {
    padding: 60px 0;
  }

  .section-title {
    font-size: 28px;
  }

  .section-subtitle {
    font-size: 15px;
    margin-bottom: 40px;
    padding: 0 16px;
  }

  .wrapper {
    padding: 0 16px;
  }

  /* 移动端导航 */
  .menu-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: 100%;
    height: calc(100vh - var(--header-height));
    background: rgba(10, 10, 10, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    justify-content: flex-start;
    align-items: center;
    padding-top: 40px;
    gap: 0;
    transform: translateX(100%);
    transition: transform 0.3s ease;
  }

  .nav-menu.open {
    transform: translateX(0);
  }

  .nav-menu a {
    font-size: 18px;
    padding: 16px 0;
    width: 100%;
    text-align: center;
    border-bottom: 1px solid var(--color-border);
  }

  .nav-menu a::after {
    display: none;
  }

  .nav-cta {
    display: none;
  }

  .mobile-cta {
    display: block;
    margin-top: 24px;
  }

  .btn {
    padding: 12px 28px;
    font-size: 15px;
  }

  /* 移动端页脚 */
  .footer-main {
    padding: 60px 0 40px;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer-bottom {
    flex-direction: column;
    text-align: center;
    gap: 8px;
  }
}

/* 小屏手机 < 390px */
@media (max-width: 389px) {
  .section-title {
    font-size: 24px;
  }

  .section-subtitle {
    font-size: 14px;
  }
}