*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --color-primary: #E63946;
  --color-accent: #F4A261;
  --color-bg: #1A1A1A;
  --color-card: #2A2A2A;
  --color-data: #2EC4B6;
  --color-text: #FFFFFF;
  --color-text-secondary: #FFE0A3;
  --color-border: #8C1C13;
  --color-primary-dark: #b0202e;
  --color-accent-dark: #d4833e;
  --color-data-glow: rgba(46, 196, 182, 0.25);
  --font-heading: 'Impact', 'Oswald', 'Arial Black', sans-serif;
  --font-body: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'Courier New', 'Consolas', 'Source Code Pro', monospace;
  --header-height: 72px;
  --content-max-width: 1280px;
  --gap: 2rem;
  --border-thick: 4px;
  --shadow-strong: 0 8px 30px rgba(0, 0, 0, 0.6);
  --radius: 0;
  --transition: 0.25s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

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

body {
  font-family: var(--font-body);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body.old-theme {
  --color-primary: #8C1C13;
  --color-accent: #B8860B;
  --color-data: #3CB371;
  --color-border: #5C1010;
  filter: sepia(0.15) saturate(0.8);
}

body.mobile-view {
  max-width: 480px;
  margin: 0 auto;
  border-left: var(--border-thick) solid var(--color-border);
  border-right: var(--border-thick) solid var(--color-border);
  min-height: 100vh;
  box-shadow: 0 0 60px rgba(0,0,0,0.8);
}

:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  z-index: 10000;
  background: var(--color-primary);
  color: var(--color-text);
  padding: 0.75rem 1.5rem;
  font-weight: 700;
  text-decoration: none;
  transition: top var(--transition);
}

.skip-link:focus-visible {
  top: 0.5rem;
}

.container {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

@media (min-width: 768px) {
  .container {
    padding: 0 2.5rem;
  }
}

@media (min-width: 1024px) {
  .container {
    padding: 0 3rem;
  }
}

/* ===== HEADER ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: transparent;
  transition: background var(--transition), box-shadow var(--transition);
  border-bottom: 2px solid transparent;
}

.header.scrolled {
  background: rgba(26, 26, 26, 0.96);
  border-bottom-color: var(--color-border);
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  position: relative;
}

.header__brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

.header__logo-icon {
  display: block;
  width: 36px;
  height: 36px;
  position: relative;
  background: radial-gradient(circle at 50% 60%, #F4A261 0%, #E63946 55%, #8C1C13 100%);
  border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
  box-shadow: 0 0 20px rgba(230, 57, 70, 0.5), inset 0 -4px 8px rgba(0,0,0,0.3);
  transform: rotate(-10deg);
  transition: transform var(--transition), box-shadow var(--transition);
}

.header__logo-icon::after {
  content: '';
  position: absolute;
  top: 6px;
  left: 8px;
  width: 18px;
  height: 10px;
  background: radial-gradient(ellipse at center, #FFE0A3 0%, transparent 70%);
  border-radius: 50%;
  opacity: 0.7;
}

.header__logo-icon:hover {
  transform: rotate(-5deg) scale(1.08);
  box-shadow: 0 0 30px rgba(230, 57, 70, 0.7), inset 0 -4px 8px rgba(0,0,0,0.3);
}

.header__logo-text {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  font-weight: 900;
  color: var(--color-text);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: none;
  filter: drop-shadow(0 2px 4px rgba(0,0,0,0.3));
}

.header__nav {
  display: none;
  position: fixed;
  top: 0;
  right: 0;
  width: 300px;
  height: 100vh;
  background: var(--color-bg);
  border-left: var(--border-thick) solid var(--color-border);
  padding: calc(var(--header-height) + 2rem) 2rem 2rem;
  z-index: 999;
  transform: translateX(100%);
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: -10px 0 40px rgba(0, 0, 0, 0.6);
}

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

.header__nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.header__nav-link {
  display: block;
  padding: 0.75rem 1rem;
  color: var(--color-text);
  text-decoration: none;
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  border-left: 3px solid transparent;
  transition: color var(--transition), border-color var(--transition), background var(--transition);
  position: relative;
}

.header__nav-link::before {
  content: attr(data-index);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-text-secondary);
  opacity: 0.4;
  margin-right: 0.5rem;
  display: inline-block;
  width: 1.8em;
}

.header__nav-link:hover,
.header__nav-link:focus-visible {
  color: var(--color-accent);
  border-left-color: var(--color-accent);
  background: rgba(244, 162, 97, 0.08);
}

.header__nav-link[aria-current="page"] {
  color: var(--color-accent);
  border-left-color: var(--color-accent);
  background: rgba(244, 162, 97, 0.12);
  font-weight: 900;
}

.header__nav-link[aria-current="page"]::after {
  content: '●';
  display: inline-block;
  margin-left: 0.5rem;
  color: var(--color-data);
  font-size: 0.6rem;
  vertical-align: middle;
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

.header__actions {
  display: none;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

.header__action-btn {
  font-family: var(--font-body);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.45rem 1rem;
  border: 2px solid var(--color-border);
  background: transparent;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.header__action-btn:hover,
.header__action-btn:focus-visible {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-text);
  box-shadow: 0 0 20px rgba(230, 57, 70, 0.3);
}

.header__old-btn {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.header__old-btn:hover,
.header__old-btn:focus-visible {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-bg);
  box-shadow: 0 0 20px rgba(244, 162, 97, 0.3);
}

.header__nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  background: transparent;
  border: 2px solid var(--color-border);
  padding: 8px;
  cursor: pointer;
  z-index: 1001;
  transition: border-color var(--transition);
  flex-shrink: 0;
}

.header__nav-toggle:hover,
.header__nav-toggle:focus-visible {
  border-color: var(--color-accent);
}

.toggle-line {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-text);
  transition: all var(--transition);
  transform-origin: center;
}

.header__nav-toggle[aria-expanded="true"] .toggle-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.header__nav-toggle[aria-expanded="true"] .toggle-line:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.header__nav-toggle[aria-expanded="true"] .toggle-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.header__progress {
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 2px;
  background: rgba(255, 255, 255, 0.08);
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent), var(--color-data));
  transition: width 0.1s linear;
}

@media (min-width: 1024px) {
  .header__nav {
    position: static;
    width: auto;
    height: auto;
    background: transparent;
    border-left: none;
    padding: 0;
    transform: none;
    box-shadow: none;
    display: block;
  }

  .header__nav-list {
    flex-direction: row;
    gap: 0.25rem;
  }

  .header__nav-link {
    padding: 0.5rem 1rem;
    font-size: 0.95rem;
    border-left: none;
    border-bottom: 3px solid transparent;
  }

  .header__nav-link::before {
    display: none;
  }

  .header__nav-link:hover,
  .header__nav-link:focus-visible {
    border-left-color: transparent;
    border-bottom-color: var(--color-accent);
    background: transparent;
  }

  .header__nav-link[aria-current="page"] {
    border-left-color: transparent;
    border-bottom-color: var(--color-accent);
    background: transparent;
  }

  .header__actions {
    display: flex;
  }

  .header__nav-toggle {
    display: none;
  }
}

/* ===== FOOTER ===== */
.footer {
  background: var(--color-bg);
  border-top: var(--border-thick) solid var(--color-border);
  padding: 3rem 0 2rem;
  margin-top: 4rem;
  position: relative;
}

.footer::before {
  content: '';
  position: absolute;
  top: -4px;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent), var(--color-data), var(--color-primary));
  background-size: 200% 100%;
  animation: shimmer 4s ease-in-out infinite;
}

@keyframes shimmer {
  0%, 100% { background-position: 0% 0%; }
  50% { background-position: 100% 0%; }
}

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

@media (min-width: 768px) {
  .footer__inner {
    grid-template-columns: 2fr 1fr 1.5fr;
    grid-template-rows: auto auto;
  }
  .footer__brand { grid-column: 1; }
  .footer__links { grid-column: 2; }
  .footer__contact { grid-column: 3; }
  .footer__bottom { grid-column: 1 / -1; }
}

.footer__brand {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer__logo-icon {
  display: block;
  width: 40px;
  height: 40px;
  background: radial-gradient(circle at 50% 60%, #F4A261 0%, #E63946 55%, #8C1C13 100%);
  border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
  box-shadow: 0 0 20px rgba(230, 57, 70, 0.4);
  transform: rotate(-10deg);
}

.footer__logo-text {
  font-family: var(--font-heading);
  font-size: 1.8rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 0.04em;
}

.footer__trust {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  max-width: 28em;
  line-height: 1.6;
  border-left: 3px solid var(--color-primary);
  padding-left: 1rem;
}

.footer__links {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding-top: 0.25rem;
}

.footer__link {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.35rem 0;
  border-bottom: 1px solid transparent;
  transition: color var(--transition), border-color var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.footer__link::before {
  content: '▸';
  color: var(--color-primary);
  font-size: 0.8rem;
}

.footer__link:hover,
.footer__link:focus-visible {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.footer__contact {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding-top: 0.25rem;
}

.footer__contact-item {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

.footer__email,
.footer__phone {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition);
}

.footer__email:hover,
.footer__phone:hover,
.footer__email:focus-visible,
.footer__phone:focus-visible {
  color: var(--color-primary);
  text-decoration: underline;
}

.footer__bottom {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  margin-top: 0.5rem;
}

@media (min-width: 768px) {
  .footer__bottom {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }
}

.footer__copyright,
.footer__icp {
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.35);
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

/* ===== BASE TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 900;
  color: var(--color-text);
  line-height: 1.2;
  letter-spacing: 0.02em;
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); margin-bottom: 1.5rem; }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.5rem); margin-bottom: 1.2rem; }
h3 { font-size: clamp(1.2rem, 2.5vw, 1.8rem); margin-bottom: 1rem; }

p {
  margin-bottom: 1rem;
  color: var(--color-text);
}

a {
  color: var(--color-accent);
  transition: color var(--transition);
}

a:hover {
  color: var(--color-primary);
}

::selection {
  background: var(--color-primary);
  color: var(--color-text);
}

/* ===== COMMON COMPONENTS ===== */
.card {
  background: var(--color-card);
  border: var(--border-thick) solid var(--color-border);
  padding: 1.5rem;
  box-shadow: var(--shadow-strong);
  transition: border-color var(--transition), transform var(--transition);
}

.card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  padding: 0.75rem 1.8rem;
  background: var(--color-primary);
  color: var(--color-text);
  border: 2px solid var(--color-primary);
  cursor: pointer;
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 40%, rgba(255,255,255,0.1) 100%);
  pointer-events: none;
}

.btn:hover,
.btn:focus-visible {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-bg);
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(244, 162, 97, 0.3);
}

.btn:active {
  transform: translateY(0);
}

.btn--outline {
  background: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.btn--outline:hover,
.btn--outline:focus-visible {
  background: var(--color-accent);
  color: var(--color-bg);
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.8rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  border: 1px solid var(--color-data);
  color: var(--color-data);
  background: rgba(46, 196, 182, 0.08);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.divider {
  width: 100%;
  height: var(--border-thick);
  background: var(--color-border);
  margin: 2.5rem 0;
  position: relative;
}

.divider::after {
  content: '//';
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--color-primary);
  background: var(--color-bg);
  padding: 0 0.75rem;
}

.grid {
  display: grid;
  gap: var(--gap);
}

.grid--2 { grid-template-columns: 1fr; }
.grid--3 { grid-template-columns: 1fr; }
.grid--4 { grid-template-columns: 1fr; }

@media (min-width: 640px) {
  .grid--2 { grid-template-columns: 1fr 1fr; }
  .grid--3 { grid-template-columns: 1fr 1fr; }
}

@media (min-width: 1024px) {
  .grid--3 { grid-template-columns: 1fr 1fr 1fr; }
  .grid--4 { grid-template-columns: 1fr 1fr 1fr 1fr; }
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem;
  padding: 0.75rem 0;
  font-size: 0.85rem;
  font-family: var(--font-mono);
  color: var(--color-text-secondary);
  list-style: none;
}

.breadcrumb li {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.breadcrumb li + li::before {
  content: '/';
  color: var(--color-border);
  margin: 0 0.25rem;
  font-weight: 700;
}

.breadcrumb a {
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition);
}

.breadcrumb a:hover,
.breadcrumb a:focus-visible {
  color: var(--color-accent);
}

.breadcrumb [aria-current="page"] {
  color: var(--color-accent);
  font-weight: 700;
}

/* ===== BACK TO TOP ===== */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 50px;
  height: 50px;
  background: var(--color-card);
  border: var(--border-thick) solid var(--color-border);
  color: var(--color-text);
  font-size: 1.4rem;
  cursor: pointer;
  z-index: 900;
  opacity: 0;
  transform: translateY(20px) scale(0.9);
  transition: opacity var(--transition), transform var(--transition), border-color var(--transition), background var(--transition);
  pointer-events: none;
  display: flex;
  align-items: center;
  justify-content: center;
}

.back-to-top.visible {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.back-to-top:hover,
.back-to-top:focus-visible {
  border-color: var(--color-accent);
  background: var(--color-primary);
  transform: translateY(-4px) scale(1.05);
  box-shadow: 0 8px 30px rgba(230, 57, 70, 0.4);
}

/* ===== DATA VISUALIZATION STYLES ===== */
.data-value {
  font-family: var(--font-mono);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-data);
  letter-spacing: 0.02em;
}

.data-value--large {
  font-size: 2.2rem;
  text-shadow: 0 0 20px var(--color-data-glow);
}

.data-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* ===== RESPONSIVE UTILITIES ===== */
@media (max-width: 767px) {
  .hide-mobile { display: none !important; }
}

@media (min-width: 768px) and (max-width: 1023px) {
  .hide-tablet { display: none !important; }
}

@media (min-width: 1024px) {
  .hide-desktop { display: none !important; }
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  html {
    scroll-behavior: auto;
  }
  .header__nav-link[aria-current="page"]::after {
    animation: none;
  }
  .footer::before {
    animation: none;
  }
  .header__logo-icon {
    transition: none;
  }
  .card {
    transition: none;
  }
  .btn {
    transition: none;
  }
  .back-to-top {
    transition: none;
  }
}