/* ============================================
   鑫达钢构 - 共享样式表
   ============================================ */

/* === Brand Colors === */
:root {
  --color-primary: #1B3A5C;
  --color-primary-50: #E8EEF4;
  --color-primary-100: #C5D4E4;
  --color-primary-200: #9FB8D1;
  --color-primary-300: #799BBE;
  --color-primary-400: #5C85AF;
  --color-primary-500: #3F6FA0;
  --color-primary-600: #3A6593;
  --color-primary-700: #2F5380;
  --color-primary-800: #254269;
  --color-primary-900: #1B3A5C;
  --color-primary-950: #0F2235;

  --color-secondary: #C8973E;
  --color-secondary-50: #FBF6ED;
  --color-secondary-100: #F3E8CF;
  --color-secondary-200: #EAD6AB;
  --color-secondary-300: #E1C486;
  --color-secondary-400: #DAB56C;
  --color-secondary-500: #C8973E;
  --color-secondary-600: #BA8833;
  --color-secondary-700: #A67529;
  --color-secondary-800: #8F6324;
  --color-secondary-900: #7A5423;
  --color-secondary-950: #4A3010;

  --color-neutral-50: #F7F8FA;
  --color-neutral-100: #EBEEF2;
  --color-neutral-200: #D4D9E1;
  --color-neutral-300: #B0B9C6;
  --color-neutral-400: #8894A5;
  --color-neutral-500: #6B7789;
  --color-neutral-600: #555F6E;
  --color-neutral-700: #464E5A;
  --color-neutral-800: #3C424B;
  --color-neutral-900: #2D3239;
  --color-neutral-950: #1A1D22;

  --color-surface: #FFFFFF;
  --color-surface-secondary: #F7F8FA;
  --color-surface-tertiary: #EBEEF2;
  --color-text-primary: #1A1D22;
  --color-text-secondary: #555F6E;
  --color-text-tertiary: #8894A5;
  --color-text-inverse: #FFFFFF;
  --color-border: #D4D9E1;
  --color-border-strong: #B0B9C6;

  /* State Colors */
  --state-success: #2D8A56;
  --state-warning: #D4920B;
  --state-error: #C53030;
  --state-info: #2B6CB0;

  /* === Typography === */
  --font-sans: "Inter", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-display: "Inter", "Noto Sans SC", "PingFang SC", sans-serif;
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
  --font-extrabold: 800;
  --leading-tight: 1.25;
  --leading-snug: 1.35;
  --leading-normal: 1.5;
  --leading-relaxed: 1.65;

  /* === Spacing === */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  --spacing-4xl: 6rem;

  /* === Border Radius === */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* === Shadows === */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.04);
  --shadow-md: 0 2px 8px rgba(0,0,0,0.05);
  --shadow-lg: 0 4px 16px rgba(0,0,0,0.05);
  --shadow-xl: 0 8px 32px rgba(0,0,0,0.06);
  --shadow-float: 0 12px 48px rgba(0,0,0,0.12);

  /* === Transitions === */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--color-surface);
  color: var(--color-text-primary);
  line-height: 1.5;
  min-height: 100vh;
}

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

ul, ol {
  list-style: none;
}

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

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

/* === Scrollbar === */
.no-scrollbar::-webkit-scrollbar { display: none; }
.no-scrollbar { -ms-overflow-style: none; scrollbar-width: none; }

/* === Layout === */
.container {
  max-width: 1280px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

@media (min-width: 1024px) {
  .container {
    padding-left: 2rem;
    padding-right: 2rem;
  }
}

/* === Navigation === */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  height: 64px;
  display: flex;
  align-items: center;
}

.nav--home {
  background: var(--color-primary-900);
}

.nav--inner {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}

.nav__inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  height: 100%;
}

@media (min-width: 1024px) {
  .nav__inner {
    padding: 0 2rem;
  }
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-shrink: 0;
  color: var(--color-secondary);
  font-size: 1.125rem;
  font-weight: var(--font-semibold);
  letter-spacing: 0.02em;
}

.nav__logo--dark {
  color: var(--color-primary);
}

.nav__links {
  display: none;
  align-items: center;
  gap: 2rem;
}

@media (min-width: 768px) {
  .nav__links {
    display: flex;
  }
}

.nav__link {
  font-size: 0.875rem;
  font-weight: var(--font-medium);
  white-space: nowrap;
  transition: opacity var(--transition-fast);
}

.nav--home .nav__link {
  color: var(--color-neutral-300);
}

.nav__link:hover {
  opacity: 0.8;
}

.nav__link--active {
  color: var(--color-text-inverse) !important;
  border-bottom: 2px solid var(--color-secondary);
  padding-bottom: 2px;
}

.nav--inner .nav__link {
  color: var(--color-text-secondary);
}

.nav--inner .nav__link--active {
  color: var(--color-primary) !important;
  font-weight: var(--font-semibold);
  border-bottom: none;
  padding-bottom: 0;
}

.nav__cta {
  display: none;
  align-items: center;
  padding: 0.5rem 1.25rem;
  font-size: 0.875rem;
  font-weight: var(--font-semibold);
  border-radius: var(--radius-md);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  white-space: nowrap;
}

.nav__cta:hover {
  transform: translateY(-1px);
}

@media (min-width: 768px) {
  .nav__cta {
    display: inline-flex;
  }
}

.nav__cta--home {
  background: var(--color-secondary);
  color: var(--color-primary-950);
}

.nav__cta--inner {
  background: var(--color-secondary);
  color: var(--color-primary-950);
}

/* Mobile menu button */
.nav__toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem;
  border-radius: var(--radius-md);
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-inverse);
  transition: background var(--transition-fast);
}

.nav--inner .nav__toggle {
  color: var(--color-text-primary);
}

.nav__toggle:hover {
  background: rgba(255,255,255,0.1);
}

@media (min-width: 768px) {
  .nav__toggle {
    display: none;
  }
}

/* Mobile menu overlay */
.mobile-menu {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(0,0,0,0.5);
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.mobile-menu--open {
  display: block;
  opacity: 1;
}

.mobile-menu__panel {
  position: absolute;
  right: 0;
  top: 0;
  bottom: 0;
  width: 280px;
  max-width: 80vw;
  background: var(--color-primary-950);
  padding: 1.5rem;
  transform: translateX(100%);
  transition: transform var(--transition-normal);
}

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

.mobile-menu__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
}

.mobile-menu__close {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem;
  border-radius: var(--radius-md);
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-inverse);
}

.mobile-menu__links {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.mobile-menu__link {
  display: block;
  padding: 0.875rem 0;
  font-size: 1rem;
  font-weight: var(--font-medium);
  color: var(--color-neutral-300);
  border-bottom: 1px solid rgba(255,255,255,0.08);
  transition: color var(--transition-fast);
}

.mobile-menu__link:hover,
.mobile-menu__link--active {
  color: var(--color-secondary);
}

.mobile-menu__cta {
  display: block;
  margin-top: 1.5rem;
  padding: 0.75rem;
  text-align: center;
  font-size: 0.875rem;
  font-weight: var(--font-semibold);
  border-radius: var(--radius-md);
  background: var(--color-secondary);
  color: var(--color-primary-950);
}

/* === Page Banner (inner pages) === */
.page-banner {
  padding-top: 5rem;
  padding-bottom: 4rem;
  background: linear-gradient(135deg, var(--color-primary-900) 0%, var(--color-primary-950) 100%);
}

@media (min-width: 1024px) {
  .page-banner {
    padding-top: 6.5rem;
    padding-bottom: 5rem;
  }
}

.page-banner__title {
  font-size: var(--text-3xl);
  font-weight: var(--font-bold);
  color: var(--color-text-inverse);
  line-height: 1.2;
  font-family: var(--font-display);
  text-wrap: balance;
  word-break: keep-all;
  overflow-wrap: break-word;
}

@media (min-width: 1024px) {
  .page-banner__title {
    font-size: var(--text-5xl);
  }
}

.page-banner__subtitle {
  margin-top: 1rem;
  font-size: var(--text-lg);
  color: var(--color-primary-200);
}

/* === Section Styles === */
.section {
  padding: 4rem 0;
}

@media (min-width: 1024px) {
  .section {
    padding: 5rem 0;
  }
}

.section--surface { background: var(--color-surface); }
.section--secondary { background: var(--color-surface-secondary); }
.section--primary { background: var(--color-primary-900); }
.section--primary-dark { background: var(--color-primary-950); }

.section__header {
  text-align: center;
  margin-bottom: 3rem;
}

.section__title {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  color: var(--color-primary-900);
  font-family: var(--font-display);
  text-wrap: balance;
  word-break: keep-all;
}

@media (min-width: 1024px) {
  .section__title {
    font-size: var(--text-3xl);
  }
}

.section__title--light {
  color: var(--color-text-inverse);
}

.section__bar {
  margin: 0.75rem auto 0;
  width: 3rem;
  height: 2px;
  border-radius: 9999px;
  background: var(--color-secondary);
}

.section__desc {
  margin-top: 0.75rem;
  font-size: var(--text-base);
  color: var(--color-text-secondary);
}

/* === Card Base === */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--color-secondary-400);
}

/* === Button Base === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-weight: var(--font-semibold);
  border-radius: var(--radius-md);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  white-space: nowrap;
  cursor: pointer;
  border: none;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn--primary {
  background: var(--color-secondary);
  color: var(--color-primary-950);
  padding: 0.75rem 1.75rem;
  font-size: 1rem;
}

.btn--outline {
  background: transparent;
  color: var(--color-text-inverse);
  border: 1px solid var(--color-neutral-300);
  padding: 0.75rem 1.75rem;
  font-size: 1rem;
}

.btn--solid {
  background: var(--color-primary);
  color: var(--color-text-inverse);
  padding: 0.75rem 2rem;
  font-size: 0.875rem;
}

.btn--lg {
  padding: 0.875rem 2rem;
  font-size: 1.125rem;
}

/* === Footer === */
.footer {
  background: var(--color-primary-950);
}

.footer__inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

@media (min-width: 1024px) {
  .footer__inner {
    padding: 4rem 2rem;
  }
}

.footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

@media (min-width: 640px) {
  .footer__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .footer__grid {
    grid-template-columns: repeat(4, 1fr);
    gap: 2.5rem;
  }
}

.footer__brand-title {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--color-secondary);
  font-size: 1rem;
  font-weight: var(--font-semibold);
}

.footer__brand-desc {
  margin-top: 1rem;
  font-size: 0.875rem;
  line-height: 1.65;
  color: rgba(255,255,255,0.5);
}

.footer__heading {
  font-size: 0.875rem;
  font-weight: var(--font-semibold);
  color: rgba(255,255,255,0.7);
  margin-bottom: 1rem;
}

.footer__list {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.footer__link {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.4);
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--color-secondary);
}

.footer__contact-item {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: rgba(255,255,255,0.4);
}

.footer__contact-item svg {
  width: 1rem;
  height: 1rem;
  flex-shrink: 0;
  margin-top: 0.15rem;
  color: var(--color-secondary);
}

.footer__bottom {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.06);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

@media (min-width: 640px) {
  .footer__bottom {
    flex-direction: row;
    justify-content: space-between;
  }
}

.footer__copyright {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.3);
}

.footer__legal {
  display: flex;
  gap: 1.5rem;
}

.footer__legal a {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.3);
  transition: color var(--transition-fast);
}

.footer__legal a:hover {
  color: rgba(255,255,255,0.7);
}

/* === Animations === */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate-fade-in-up {
  opacity: 0;
  animation: fadeInUp 0.6s ease forwards;
}

.animate-delay-1 { animation-delay: 0.1s; }
.animate-delay-2 { animation-delay: 0.2s; }
.animate-delay-3 { animation-delay: 0.3s; }
.animate-delay-4 { animation-delay: 0.4s; }

/* === Utility === */
.text-balance {
  text-wrap: balance;
}

.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.line-clamp-2 {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.line-clamp-3 {
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* Case card hover effects */
.case-card {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
  cursor: pointer;
  border: 2px solid transparent;
  transition: border-color 150ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.case-card:hover {
  border-color: var(--color-secondary);
}

.case-card img {
  transition: transform 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.case-card:hover img {
  transform: scale(1.05);
}

.case-overlay {
  opacity: 0;
  transition: opacity 200ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.case-card:hover .case-overlay {
  opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
  .case-overlay, .case-card, .case-card img {
    transition-duration: 0.01ms;
  }
}

/* Scroll reveal */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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