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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  font-size: 16px;
}

body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
  font-weight: 400;
  line-height: 1.6;
  color: #FFFFFF;
  background-color: #2B2D42;
  min-height: 100vh;
  overflow-x: hidden;
}

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

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s ease, box-shadow 0.2s ease;
}

ul, ol {
  list-style: none;
}

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

:focus-visible {
  outline: 2px solid #00F5D4;
  outline-offset: 2px;
  border-radius: 2px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ===== CSS Variables ===== */
:root {
  --color-red: #E63946;
  --color-blue: #1D3557;
  --color-gold: #F4A261;
  --color-dark: #2B2D42;
  --color-mid: #8D99AE;
  --color-white: #FFFFFF;
  --color-neon: #00F5D4;
  --color-purple: #6C5CE7;
  --color-red-glow: rgba(230, 57, 70, 0.4);
  --color-neon-glow: rgba(0, 245, 212, 0.35);
  --color-gold-glow: rgba(244, 162, 97, 0.3);
  --header-width: 240px;
  --header-width-mobile: 0px;
  --transition-fast: 0.2s ease;
  --transition-med: 0.35s ease;
  --transition-slow: 0.5s cubic-bezier(0.22, 1, 0.36, 1);
  --font-heading: 'Impact', 'Arial Black', 'Helvetica Neue', sans-serif;
  --font-body: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
  --font-mono: 'Courier New', 'Consolas', 'Liberation Mono', monospace;
}

/* ===== Skip Link ===== */
.skip-link {
  position: absolute;
  top: -100%;
  left: 0;
  z-index: 10000;
  padding: 0.5rem 1.2rem;
  background: var(--color-red);
  color: var(--color-white);
  font-weight: 700;
  font-size: 0.875rem;
  clip: rect(1px, 1px, 1px, 1px);
  transition: top 0.25s ease;
}
.skip-link:focus {
  top: 0;
  clip: auto;
  outline: 2px solid var(--color-neon);
  outline-offset: 2px;
}

/* ===== Header — Desktop Sidebar ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--header-width);
  height: 100vh;
  z-index: 1000;
  background: linear-gradient(180deg, #1D3557 0%, #2B2D42 100%);
  border-right: 3px solid var(--color-neon);
  box-shadow: 4px 0 20px rgba(0,0,0,0.5);
  display: flex;
  flex-direction: column;
}

.header-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: 1.5rem 1rem;
  gap: 0;
}

/* Brand Logo */
.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid rgba(244, 162, 97, 0.25);
  margin-bottom: 1.5rem;
  flex-shrink: 0;
}

.brand-icon {
  display: block;
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, #E63946 49%, #1D3557 51%);
  transform: rotate(45deg);
  border: 2px solid #F4A261;
  box-shadow: 0 0 10px rgba(244, 162, 97, 0.3);
  flex-shrink: 0;
}

.brand-text {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--color-white);
  line-height: 1.1;
}
.brand-highlight {
  color: var(--color-gold);
  text-shadow: 0 0 8px rgba(244, 162, 97, 0.3);
}

/* Navigation */
.site-nav {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.nav-list {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.nav-list a {
  display: block;
  padding: 0.6rem 0.75rem;
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--color-mid);
  border-left: 3px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
  border-radius: 0 4px 4px 0;
}

.nav-list a:hover {
  color: var(--color-gold);
  border-left-color: var(--color-gold);
  background: rgba(244, 162, 97, 0.08);
}

.nav-list a[aria-current="page"] {
  color: var(--color-neon);
  border-left-color: var(--color-neon);
  background: rgba(0, 245, 212, 0.1);
  text-shadow: 0 0 6px rgba(0, 245, 212, 0.25);
}

/* Header CTA */
.header-cta {
  flex-shrink: 0;
  margin-top: auto;
  display: block;
  text-align: center;
}

/* Nav Toggle — Hidden on Desktop */
.nav-toggle {
  display: none;
  flex-shrink: 0;
}

/* ===== Mobile Header (max-width: 1023px) ===== */
@media (max-width: 1023px) {
  .site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: auto;
    border-right: none;
    border-bottom: 2px solid var(--color-neon);
    box-shadow: 0 2px 16px rgba(0,0,0,0.4);
    background: linear-gradient(135deg, #1D3557 0%, #2B2D42 100%);
    z-index: 1000;
  }

  .header-inner {
    flex-direction: row;
    align-items: center;
    height: auto;
    padding: 0.6rem 1rem;
    gap: 0.5rem;
  }

  .brand-logo {
    padding: 0;
    margin: 0;
    border: none;
    flex-shrink: 0;
  }

  .brand-icon {
    width: 28px;
    height: 28px;
  }

  .brand-text {
    font-size: 1rem;
  }

  .header-cta {
    margin: 0;
    margin-left: auto;
    padding: 0.3rem 0.8rem;
    font-size: 0.75rem;
  }

  .nav-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 36px;
    height: 36px;
    gap: 4px;
    margin-left: 0.4rem;
    background: transparent;
    border: 1px solid rgba(244, 162, 97, 0.25);
    border-radius: 4px;
    padding: 6px;
    transition: border-color var(--transition-fast), background var(--transition-fast);
  }
  .nav-toggle:hover {
    border-color: var(--color-gold);
    background: rgba(244, 162, 97, 0.1);
  }
  .nav-toggle:focus-visible {
    outline: 2px solid var(--color-neon);
    outline-offset: 2px;
  }

  .toggle-bar {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--color-white);
    border-radius: 2px;
    transition: transform var(--transition-med), opacity var(--transition-med);
  }

  /* Mobile Nav — Drawer */
  .site-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 280px;
    height: 100vh;
    background: linear-gradient(180deg, #1D3557 0%, #2B2D42 100%);
    border-right: 3px solid var(--color-neon);
    box-shadow: 4px 0 30px rgba(0,0,0,0.6);
    transform: translateX(-100%);
    transition: transform var(--transition-slow);
    padding: 2rem 1.5rem;
    z-index: 2000;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
  }

  .site-nav[data-open] {
    transform: translateX(0);
  }

  .site-nav::before {
    content: "K1体育 38体验";
    display: block;
    font-family: var(--font-heading);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-gold);
    letter-spacing: 0.04em;
    padding-bottom: 1.2rem;
    margin-bottom: 1.2rem;
    border-bottom: 1px solid rgba(244, 162, 97, 0.2);
  }

  .nav-list {
    gap: 0.15rem;
  }

  .nav-list a {
    font-size: 1.05rem;
    padding: 0.75rem 0.75rem;
  }

  /* Overlay when nav open */
  .site-nav[data-open] ~ .nav-overlay,
  .header-inner .nav-overlay {
    display: none;
  }

  /* We create overlay via JS instead of static element to keep DOM clean */
  body.nav-open::after {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.55);
    backdrop-filter: blur(3px);
    z-index: 1500;
    animation: fadeInOverlay 0.3s ease;
  }

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

/* ===== Main Content Area ===== */
#main-content {
  padding-left: var(--header-width);
  min-height: 80vh;
  position: relative;
  z-index: 1;
}

@media (max-width: 1023px) {
  #main-content {
    padding-left: 0;
    padding-top: 60px;
  }
}

/* ===== Footer ===== */
.site-footer {
  background: #1D3557;
  border-top: 3px solid var(--color-neon);
  padding: 2.5rem 2rem 1.5rem;
  margin-left: var(--header-width);
  position: relative;
  z-index: 1;
}

@media (max-width: 1023px) {
  .site-footer {
    margin-left: 0;
    padding: 2rem 1.2rem 1.2rem;
  }
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
}

.footer-top {
  display: grid;
  grid-template-columns: 1fr 1fr 1.5fr;
  gap: 2rem;
  padding-bottom: 1.8rem;
  border-bottom: 1px solid rgba(244, 162, 97, 0.2);
  margin-bottom: 1.2rem;
}

@media (max-width: 767px) {
  .footer-top {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
}

.footer-logo {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-white);
  letter-spacing: 0.04em;
  display: block;
  margin-bottom: 0.4rem;
}

.footer-desc {
  font-size: 0.85rem;
  color: var(--color-mid);
  line-height: 1.5;
}

.footer-nav {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-nav a {
  font-size: 0.9rem;
  color: var(--color-mid);
  transition: color var(--transition-fast), padding-left var(--transition-fast);
  padding-left: 0;
}
.footer-nav a:hover {
  color: var(--color-gold);
  padding-left: 4px;
}

.footer-contact {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.85rem;
  color: var(--color-mid);
  line-height: 1.5;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.8rem;
  font-size: 0.75rem;
  color: var(--color-mid);
}

.footer-icp {
  color: var(--color-mid);
  letter-spacing: 0.03em;
}

.footer-note {
  color: var(--color-mid);
  opacity: 0.75;
  font-style: italic;
  max-width: 480px;
}

@media (max-width: 600px) {
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem 1.4rem;
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  border-radius: 4px;
  transition: all var(--transition-fast);
  cursor: pointer;
  text-align: center;
}

.btn-neon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem 1.4rem;
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--color-white);
  background: var(--color-red);
  border: 1px solid var(--color-red);
  border-radius: 4px;
  box-shadow: 0 0 8px rgba(230, 57, 70, 0.3);
  transition: all var(--transition-fast);
  text-align: center;
}

.btn-neon:hover {
  background: #d62d3a;
  box-shadow: 0 0 18px rgba(230, 57, 70, 0.6), 0 0 30px rgba(230, 57, 70, 0.2);
  transform: translateY(-1px);
  color: var(--color-white);
}

.btn-neon:focus-visible {
  outline: 2px solid var(--color-neon);
  outline-offset: 2px;
  box-shadow: 0 0 18px rgba(230, 57, 70, 0.5), 0 0 0 2px var(--color-neon);
}

/* ===== Progress Bar ===== */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--color-red), var(--color-neon));
  z-index: 9999;
  transition: width 0.1s linear;
  pointer-events: none;
}

@media (max-width: 1023px) {
  .progress-bar {
    top: auto;
    bottom: 0;
    height: 3px;
  }
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-blue);
  border: 2px solid var(--color-gold);
  color: var(--color-gold);
  font-size: 1.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 12px rgba(244, 162, 97, 0.2);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all var(--transition-med);
  z-index: 999;
  cursor: pointer;
}
.back-to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover {
  background: var(--color-gold);
  color: var(--color-blue);
  box-shadow: 0 0 20px rgba(244, 162, 97, 0.5);
}
.back-to-top:focus-visible {
  outline: 2px solid var(--color-neon);
  outline-offset: 2px;
}

/* ===== Image Container Base ===== */
.img-container {
  position: relative;
  overflow: hidden;
  background: var(--color-dark);
  border: 1px solid rgba(244, 162, 97, 0.15);
  border-radius: 4px;
}
.img-container::before {
  content: "";
  display: block;
  padding-top: 56.25%;
}
.img-placeholder {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-mid);
  font-size: 0.85rem;
  font-family: var(--font-mono);
  background: linear-gradient(135deg, rgba(29,53,87,0.4) 0%, rgba(43,45,66,0.6) 100%);
}

/* ===== Utility ===== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 3rem 0;
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  html {
    scroll-behavior: auto;
  }
  .site-nav {
    transition: none;
  }
  .back-to-top {
    transition: none;
  }
}