:root {
  --c-bg: #0B1424;
  --c-panel: #101E30;
  --c-float: #16273E;
  --c-line: #233A52;
  --c-red: #E23B4E;
  --c-red-bright: #FF6B6B;
  --c-silver: #B8C4D0;
  --c-gray: #7F8FA0;
  --c-text: #EEF2F6;
  --c-green: #7FA88C;
  --font-display: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", "Consolas", monospace;
  --header-w: 17rem;
  --container-max: 80rem;
  --cut-size: 1.25rem;
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --shadow: 0 1rem 2rem rgba(0, 0, 0, 0.3);
}

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

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

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-display);
  font-weight: 900;
  line-height: 1.15;
  color: var(--c-text);
  margin: 0 0 1rem;
}

h1 {
  font-size: clamp(2rem, 4vw, 3.5rem);
}

h2 {
  font-size: clamp(1.5rem, 2.6vw, 2.5rem);
}

h3 {
  font-size: clamp(1.25rem, 2vw, 1.75rem);
}

p {
  margin: 0 0 1rem;
}

a {
  color: var(--c-red-bright);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--c-red);
}

small {
  color: var(--c-gray);
}

body {
  margin-left: var(--header-w);
}

.skip-link {
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 2000;
  transform: translateY(-200%);
  background: var(--c-red);
  color: #fff;
  padding: 0.75rem 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-decoration: none;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease;
}

.skip-link:focus {
  transform: translateY(0);
  outline: 2px solid var(--c-text);
  outline-offset: 2px;
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--header-w);
  height: 100vh;
  background: linear-gradient(180deg, var(--c-float) 0%, var(--c-panel) 100%);
  border-right: 1px solid var(--c-line);
  display: flex;
  flex-direction: column;
  z-index: 1000;
  overflow-y: auto;
}

.site-header__meta {
  padding: 0.75rem 1rem;
  background: var(--c-bg);
  border-bottom: 1px solid var(--c-line);
}

.site-header__note {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.03em;
  color: var(--c-gray);
  line-height: 1.5;
}

.site-header__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1rem 0.25rem;
}

.site-brand {
  display: flex;
  flex-direction: column;
  text-decoration: none;
}

.site-brand__logo {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.5rem;
  letter-spacing: 0.02em;
  color: var(--c-text);
  line-height: 1.1;
  display: flex;
  align-items: center;
}

.site-brand__logo::before {
  content: "";
  width: 14px;
  height: 14px;
  background: var(--c-red);
  display: inline-block;
  margin-right: 0.6rem;
  clip-path: polygon(0 0, 100% 0, 100% 100%, 0 70%);
}

.site-header__domain {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.02em;
  color: var(--c-gray);
  margin-top: 0.25rem;
}

.nav-toggle {
  display: none;
}

.site-nav {
  margin-top: 1.5rem;
  padding-bottom: 2rem;
}

.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--c-text);
  text-decoration: none;
  border-left: 3px solid transparent;
  transition: color 0.2s, background 0.2s, border-color 0.2s;
}

.site-nav a:hover {
  color: var(--c-red-bright);
  background: linear-gradient(90deg, rgba(226, 59, 78, 0.12), transparent);
}

.site-nav a[aria-current="page"] {
  color: var(--c-red-bright);
  background: linear-gradient(90deg, rgba(226, 59, 78, 0.16), transparent);
  border-left-color: var(--c-red);
}

.nav-index {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  color: var(--c-gray);
  min-width: 2rem;
}

.site-nav a:hover .nav-index,
.site-nav a[aria-current="page"] .nav-index {
  color: var(--c-red-bright);
}

.site-header__progress {
  margin-top: auto;
  height: 3px;
  background: rgba(255, 255, 255, 0.08);
}

.site-header__progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--c-red), var(--c-red-bright));
}

.site-footer {
  background: var(--c-bg);
  border-top: 1px solid var(--c-line);
  padding: 3rem clamp(1.5rem, 4vw, 2rem) 2rem;
  margin-top: 4rem;
  position: relative;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--c-red), transparent 60%);
}

.site-footer__grid {
  max-width: var(--container-max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 2fr;
  gap: 2rem;
}

.site-footer__brand .site-footer__logo {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.5rem;
  color: var(--c-text);
}

.site-footer__copyright {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--c-gray);
  margin-top: 0.5rem;
}

.site-footer__title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--c-silver);
  margin-bottom: 0.75rem;
  text-transform: uppercase;
}

.site-footer ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-footer li {
  margin-bottom: 0.5rem;
  font-size: 0.875rem;
  color: var(--c-silver);
}

.site-footer a {
  color: var(--c-silver);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s, border-color 0.2s;
}

.site-footer a:hover {
  color: var(--c-red-bright);
  border-bottom-color: var(--c-red);
}

.site-footer__contact-item {
  color: var(--c-silver);
}

.site-footer__note {
  max-width: var(--container-max);
  margin: 2rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--c-line);
  font-size: 0.8125rem;
  color: var(--c-gray);
}

.c-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 clamp(1rem, 4vw, 2rem);
}

.c-section {
  padding: clamp(3rem, 8vw, 5rem) 0;
}

.c-section--tight {
  padding: clamp(1.5rem, 4vw, 2.5rem) 0;
}

.c-kicker {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: var(--c-gray);
}

.c-kicker--red {
  color: var(--c-red-bright);
}

.c-panel {
  background: var(--c-panel);
  border: 1px solid var(--c-line);
  padding: clamp(1.25rem, 3vw, 2rem);
  clip-path: polygon(0 0, calc(100% - var(--cut-size)) 0, 100% var(--cut-size), 100% 100%, 0 100%);
}

.c-panel--slant {
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut-size)), calc(100% - var(--cut-size)) 100%, 0 100%);
}

.c-btn {
  position: relative;
  display: inline-block;
  padding: 0.75rem 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  background: var(--c-panel);
  border: 1px solid var(--c-line);
  color: var(--c-text);
  text-decoration: none;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
  overflow: hidden;
}

.c-btn::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-style: solid;
  border-width: 0 0 16px 16px;
  border-color: transparent transparent var(--c-red) transparent;
}

.c-btn:hover {
  border-color: var(--c-red);
  color: var(--c-red-bright);
}

.c-btn--primary {
  background: var(--c-red);
  border-color: var(--c-red);
  color: #fff;
}

.c-btn--primary:hover {
  background: var(--c-red-bright);
  border-color: var(--c-red-bright);
  color: var(--c-bg);
}

.c-btn--primary::after {
  border-color: transparent transparent var(--c-bg) transparent;
}

.c-btn--ghost {
  background: transparent;
  border-color: var(--c-line);
}

.c-btn--ghost:hover {
  border-color: var(--c-red-bright);
  color: var(--c-red-bright);
}

.c-btn--ghost::after {
  border-color: transparent transparent var(--c-silver) transparent;
}

.c-breadcrumb {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0 0 2rem;
  padding: 0;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--c-gray);
}

.c-breadcrumb__item + .c-breadcrumb__item::before {
  content: "/";
  margin-right: 0.5rem;
  color: var(--c-line);
}

.c-breadcrumb a {
  color: var(--c-silver);
  text-decoration: none;
}

.c-breadcrumb a:hover {
  color: var(--c-red-bright);
}

.c-grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1.5rem;
}

.c-grid__main {
  grid-column: span 7;
}

.c-grid__side {
  grid-column: span 3;
}

.c-image-frame {
  position: relative;
  background: var(--c-panel);
  border: 1px solid var(--c-line);
  aspect-ratio: 16 / 9;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.c-image-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 0%, rgba(11, 20, 36, 0.5) 100%);
  pointer-events: none;
}

.c-image-frame__placeholder {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--c-gray);
  padding: 1rem;
  text-align: center;
  position: relative;
}

.c-image-frame--tall {
  aspect-ratio: 3 / 4;
}

.c-tabs__list {
  list-style: none;
  margin: 0 0 2rem;
  padding: 0;
  border-bottom: 1px solid var(--c-line);
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.c-tabs__trigger {
  background: transparent;
  border: 0;
  border-bottom: 3px solid transparent;
  padding: 0.75rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--c-gray);
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s;
}

.c-tabs__trigger:hover {
  color: var(--c-text);
}

.c-tabs__trigger[aria-selected="true"] {
  color: var(--c-red-bright);
  border-bottom-color: var(--c-red);
}

.c-tabs__panel {
  display: none;
}

.c-tabs__panel.is-active {
  display: block;
}

.c-faq__item {
  border-bottom: 1px solid var(--c-line);
}

.c-faq__question {
  width: 100%;
  background: transparent;
  border: 0;
  text-align: left;
  padding: 1.25rem 0;
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-text);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.c-faq__question:hover {
  color: var(--c-red-bright);
}

.c-faq__question[aria-expanded="true"] {
  color: var(--c-red-bright);
}

.c-faq__question::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--c-gray);
}

.c-faq__question[aria-expanded="true"]::after {
  content: "−";
}

.c-faq__answer {
  padding: 0 0 1.25rem;
  color: var(--c-silver);
}

.c-faq__answer[hidden] {
  display: none;
}

.c-divider {
  border: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--c-line), transparent);
  margin: 2rem 0;
}

.js [data-reveal] {
  opacity: 0;
  transform: translateY(1.5rem);
  transition: opacity 0.24s ease-out, transform 0.24s ease-out;
}

.js [data-reveal].is-inview {
  opacity: 1;
  transform: none;
}

:focus-visible {
  outline: 2px solid var(--c-red-bright);
  outline-offset: 2px;
}

@media (max-width: 768px) {
  body {
    margin-left: 0;
    padding-top: 3.75rem;
  }

  .site-header {
    width: 100%;
    height: auto;
    flex-direction: row;
    flex-wrap: wrap;
    border-right: 0;
    border-bottom: 1px solid var(--c-line);
  }

  .site-header__meta {
    display: none;
  }

  .site-header__bar {
    order: 1;
    width: 100%;
    padding: 0.75rem 1rem;
  }

  .nav-toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: transparent;
    border: 1px solid var(--c-line);
    color: var(--c-text);
    padding: 0.4rem 0.7rem;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    cursor: pointer;
  }

  .nav-toggle:hover {
    border-color: var(--c-red);
    color: var(--c-red-bright);
  }

  .nav-toggle__box {
    display: inline-flex;
    flex-direction: column;
    gap: 3px;
  }

  .nav-toggle__box span {
    width: 18px;
    height: 2px;
    background: currentColor;
  }

  .site-nav {
    order: 2;
    display: none;
    width: 100%;
    margin: 0;
    padding: 0;
    background: var(--c-panel);
    border-top: 1px solid var(--c-line);
    max-height: calc(100vh - 3.75rem);
    overflow-y: auto;
  }

  .site-nav[data-open] {
    display: block;
  }

  .site-nav a {
    border-left: 0;
    border-bottom: 1px solid var(--c-line);
    padding: 0.85rem 1rem;
  }

  .site-header__progress {
    order: 3;
    width: 100%;
    margin-top: 0;
  }

  .site-footer {
    padding: 2rem 1.5rem 1.5rem;
  }

  .site-footer__grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .c-grid {
    grid-template-columns: 1fr;
  }

  .c-grid__main,
  .c-grid__side {
    grid-column: span 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .js [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }

  .site-header__progress span {
    transition: none;
  }
}