/*
 * 文件名: style.css
 * 描述: 深圳市天拓光电技术有限公司 2025 企业官网全局样式
 * 设计主题: 光速传输 · 极致连接
 */

/* ==========================================================================
   1. Design Tokens
   ========================================================================== */
:root {
  --color-primary: #1ce3ff;
  --color-primary-strong: #147dff;
  --color-secondary: #ff7a1a;
  --color-tertiary: #7c5cff;
  --color-success: #3cf5a8;
  --color-warning: #ffde70;
  --color-danger: #ff4f6d;

  --color-bg: #020714;
  --color-bg-elevated: #080f24;
  --color-bg-soft: rgba(13, 22, 45, 0.82);
  --color-surface: rgba(13, 23, 48, 0.92);
  --color-surface-alt: rgba(10, 18, 38, 0.88);
  --color-border: rgba(255, 255, 255, 0.08);
  --color-divider: rgba(108, 144, 255, 0.18);

  --text-title: #f2f7ff;
  --text-body: #c0cee8;
  --text-muted: #92a5c9;
  --text-inverse: #020714;

  --font-cn: "HarmonyOS Sans", "MiSans", "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  --font-en: "Space Grotesk", "SF Pro Display", var(--font-cn);

  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-md: 1.125rem;
  --font-size-lg: 1.25rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 1.875rem;
  --font-size-3xl: 2.5rem;
  --font-size-4xl: clamp(2.5rem, 2vw + 2rem, 3.5rem);

  --line-height-tight: 1.2;
  --line-height-snug: 1.35;
  --line-height-base: 1.6;

  --spacing-2: 0.125rem;
  --spacing-4: 0.25rem;
  --spacing-6: 0.375rem;
  --spacing-8: 0.5rem;
  --spacing-12: 0.75rem;
  --spacing-16: 1rem;
  --spacing-20: 1.25rem;
  --spacing-24: 1.5rem;
  --spacing-32: 2rem;
  --spacing-40: 2.5rem;
  --spacing-48: 3rem;
  --spacing-64: 4rem;
  --section-padding: clamp(4rem, 6vw, 7rem);

  --radius-xs: 6px;
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --radius-pill: 999px;

  --shadow-soft: 0 24px 60px rgba(7, 19, 51, 0.4);
  --shadow-card: 0 18px 45px rgba(8, 26, 66, 0.35);
  --shadow-hover: 0 24px 65px rgba(16, 44, 94, 0.45);

  --transition-base: all 0.35s cubic-bezier(0.2, 0.8, 0.2, 1);
  --transition-fast: all 0.25s cubic-bezier(0.2, 0.8, 0.2, 1);

  --max-width: 1200px;
  --grid-gap: clamp(1.5rem, 2.5vw, 2.75rem);
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0s !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0s !important;
  }
}

/* ==========================================================================
   2. Base Resets & Layout
   ========================================================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background: var(--color-bg);
}

body {
  font-family: var(--font-cn);
  font-size: var(--font-size-base);
  line-height: var(--line-height-base);
  color: var(--text-body);
  background: radial-gradient(circle at 10% 20%, rgba(18, 43, 96, 0.5) 0%, rgba(2, 7, 20, 0.85) 45%, rgba(2, 7, 20, 1) 100%);
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background: linear-gradient(120deg, rgba(20, 125, 255, 0.08), rgba(124, 92, 255, 0.08) 35%, rgba(28, 227, 255, 0.08));
  pointer-events: none;
  z-index: -2;
}

body::after {
  content: "";
  position: fixed;
  inset: 0;
  background: radial-gradient(circle at 80% 20%, rgba(28, 227, 255, 0.14), transparent 45%), radial-gradient(circle at 15% 80%, rgba(255, 122, 26, 0.18), transparent 40%);
  pointer-events: none;
  z-index: -3;
}

img {
  max-width: 100%;
  display: block;
  border-radius: var(--radius-sm);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.25s ease, opacity 0.25s ease;
}

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

p {
  color: var(--text-body);
  margin-bottom: var(--spacing-16);
}

strong {
  color: var(--text-title);
  font-weight: 600;
}

section {
  padding: var(--section-padding) 0;
  position: relative;
  isolation: isolate;
}

.container {
  width: min(92%, var(--max-width));
  margin: 0 auto;
}

.stack {
  display: grid;
  gap: var(--spacing-24);
}

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

.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.grid-4 {
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-8);
  background: rgba(28, 227, 255, 0.12);
  border: 1px solid rgba(28, 227, 255, 0.25);
  color: var(--color-primary);
  padding: var(--spacing-8) var(--spacing-16);
  border-radius: var(--radius-pill);
  font-size: var(--font-size-sm);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.section-title {
  text-align: left;
  margin-bottom: var(--spacing-40);
  max-width: 640px;
}

.section-title.center {
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

.section-title h2 {
  font-size: var(--font-size-3xl);
  font-weight: 600;
  color: var(--text-title);
  line-height: var(--line-height-tight);
  margin-bottom: var(--spacing-16);
}

.section-title p {
  font-size: var(--font-size-md);
  color: var(--text-muted);
  margin-bottom: 0;
}

/* ==========================================================================
   3. Buttons & Pills
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-8);
  padding: var(--spacing-12) var(--spacing-24);
  border-radius: var(--radius-pill);
  font-size: var(--font-size-sm);
  font-weight: 600;
  letter-spacing: 0.02em;
  border: 1px solid transparent;
  cursor: pointer;
  background: transparent;
  color: var(--text-title);
  position: relative;
  overflow: hidden;
  transition: var(--transition-base);
}

.btn::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, rgba(255, 255, 255, 0.14), transparent 40%);
  opacity: 0;
  transition: opacity 0.35s ease;
}

.btn:hover::after {
  opacity: 1;
}

.btn--primary {
  background: linear-gradient(135deg, #21f2ff 0%, #147dff 60%, #7c5cff 100%);
  border-color: rgba(33, 242, 255, 0.4);
  box-shadow: 0 18px 45px rgba(20, 125, 255, 0.45);
}

.btn--ghost {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(255, 255, 255, 0.1);
  color: var(--text-title);
}

.btn--link {
  padding-inline: 0;
  border: none;
  color: var(--color-primary);
}

.btn--xs {
  padding: var(--spacing-8) var(--spacing-16);
  font-size: var(--font-size-xs);
}

.btn svg {
  width: 18px;
  height: 18px;
}

/* ==========================================================================
   4. Header & Navigation
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 900;
  background: linear-gradient(120deg, rgba(5, 12, 26, 0.9), rgba(10, 18, 35, 0.75));
  backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--color-divider);
}

.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 12% 90%, rgba(255, 122, 26, 0.18), transparent 45%);
  opacity: 0;
  transition: opacity 0.4s ease;
}

.site-header:hover::before {
  opacity: 1;
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-24);
  padding: var(--spacing-12) 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-4);
}

.brand__name {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-title);
  letter-spacing: 0.08em;
}

.brand__tagline {
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.header-utility {
  display: flex;
  align-items: center;
  gap: var(--spacing-16);
}

.header-indicators {
  display: flex;
  align-items: center;
  gap: var(--spacing-24);
}

.header-indicators__item {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-4);
  font-size: var(--font-size-xs);
  color: var(--text-muted);
}

.header-indicators__item strong {
  font-family: var(--font-en);
  font-size: 0.9rem;
  color: var(--color-primary);
  letter-spacing: 0.08em;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 6px;
  width: 42px;
  height: 42px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: rgba(255, 255, 255, 0.04);
}

.nav-toggle span {
  display: block;
  height: 2px;
  width: 20px;
  background: var(--text-title);
  border-radius: 999px;
  transition: transform 0.35s ease, opacity 0.35s ease;
  margin: 0 auto;
}

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

.main-nav__list {
  list-style: none;
  display: flex;
  align-items: center;
  gap: var(--spacing-24);
}

.main-nav__link {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-8);
  font-size: var(--font-size-sm);
  color: var(--text-body);
  font-weight: 500;
  position: relative;
  padding: var(--spacing-12) 0;
}

.main-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 6px;
  height: 2px;
  background: linear-gradient(90deg, transparent, rgba(33, 242, 255, 0.8), transparent);
  opacity: 0;
  transform: scaleX(0.3);
  transition: var(--transition-fast);
}

.main-nav__link:hover,
.main-nav__link.is-active {
  color: var(--text-title);
}

.main-nav__link:hover::after,
.main-nav__link.is-active::after {
  opacity: 1;
  transform: scaleX(1);
}

.header-cta {
  display: flex;
  align-items: center;
  gap: var(--spacing-16);
}

.header-cta .hotline {
  display: flex;
  flex-direction: column;
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 0.08em;
}

.header-cta .hotline strong {
  font-family: var(--font-en);
  font-size: 0.95rem;
  color: var(--color-secondary);
}

@media (max-width: 1080px) {
  .header-indicators {
    display: none;
  }

  .main-nav__list {
    gap: var(--spacing-16);
  }
}

@media (max-width: 900px) {
  .site-header__inner {
    flex-wrap: wrap;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .main-nav {
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background: rgba(6, 13, 30, 0.96);
    border-top: 1px solid var(--color-divider);
    padding: var(--spacing-24) 0 var(--spacing-32);
    transform: translateY(-110%);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.4s ease, opacity 0.4s ease;
  }

  .main-nav.is-open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .main-nav__list {
    flex-direction: column;
    width: min(92%, 420px);
    margin: 0 auto;
    gap: var(--spacing-12);
  }

  .main-nav__link {
    width: 100%;
    justify-content: space-between;
    padding: var(--spacing-16);
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.03);
  }

  .header-cta {
    width: 100%;
    justify-content: space-between;
  }
}

/* ==========================================================================
   5. Cards & Surfaces
   ========================================================================== */
.surface {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  padding: var(--spacing-32);
  position: relative;
  overflow: hidden;
  transition: var(--transition-base);
}

.surface::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at top right, rgba(33, 242, 255, 0.18), transparent 45%);
  z-index: -1;
  opacity: 0;
  transition: opacity 0.4s ease;
}

.surface:hover::before {
  opacity: 1;
}

.surface:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
}

.stat-card {
  padding: var(--spacing-24);
  border-radius: var(--radius-md);
  border: 1px solid rgba(33, 242, 255, 0.2);
  background: linear-gradient(135deg, rgba(18, 31, 63, 0.75), rgba(5, 10, 22, 0.9));
  display: grid;
  gap: var(--spacing-12);
}

.stat-card__label {
  font-size: var(--font-size-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.stat-card__value {
  font-family: var(--font-en);
  font-size: clamp(2rem, 3vw, 2.75rem);
  color: var(--text-title);
}

.stat-card__trend {
  display: flex;
  align-items: center;
  gap: var(--spacing-8);
  font-size: var(--font-size-xs);
  color: var(--color-success);
}

.table-responsive {
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: rgba(8, 16, 34, 0.85);
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  padding: var(--spacing-16);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  text-align: left;
  font-size: var(--font-size-sm);
}

th {
  font-weight: 600;
  color: var(--text-title);
  background: rgba(255, 255, 255, 0.03);
}

tr:hover td {
  background: rgba(28, 227, 255, 0.04);
}

/* ==========================================================================
   6. Footer
   ========================================================================== */
.site-footer {
  background: linear-gradient(180deg, rgba(5, 12, 26, 0.95), rgba(3, 8, 18, 1));
  border-top: 1px solid var(--color-divider);
  padding: var(--spacing-48) 0 var(--spacing-32);
  position: relative;
  overflow: hidden;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: -20%;
  right: -10%;
  width: 420px;
  height: 420px;
  background: radial-gradient(circle, rgba(20, 125, 255, 0.22), transparent 55%);
  filter: blur(50px);
  opacity: 0.6;
}

.site-footer__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-32);
  position: relative;
  z-index: 2;
}

.footer-brand {
  display: grid;
  gap: var(--spacing-16);
}

.footer-brand p {
  margin-bottom: 0;
}

.footer-meta {
  display: grid;
  gap: var(--spacing-8);
  font-size: var(--font-size-sm);
  color: var(--text-muted);
}

.footer-meta a {
  color: var(--text-body);
}

.footer-column h4 {
  font-size: var(--font-size-md);
  color: var(--text-title);
  margin-bottom: var(--spacing-16);
}

.footer-links {
  list-style: none;
  display: grid;
  gap: var(--spacing-12);
}

.footer-links a {
  color: var(--text-muted);
  font-size: var(--font-size-sm);
}

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

.site-footer__bottom {
  margin-top: var(--spacing-32);
  padding-top: var(--spacing-24);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-16);
  justify-content: space-between;
  font-size: var(--font-size-xs);
  color: var(--text-muted);
}

/* ==========================================================================
   7. Breadcrumb & Page Scaffolding
   ========================================================================== */
.page-hero {
  padding: clamp(120px, 22vh, 220px) 0 clamp(3rem, 6vw, 4.5rem);
  background: linear-gradient(140deg, rgba(20, 125, 255, 0.16), rgba(124, 92, 255, 0.1), rgba(3, 7, 18, 0.1));
  position: relative;
}

.page-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 20% 40%, rgba(28, 227, 255, 0.2), transparent 60%), radial-gradient(circle at 80% 20%, rgba(255, 122, 26, 0.18), transparent 60%);
  mix-blend-mode: screen;
  opacity: 0.8;
}

.page-hero .section-title {
  max-width: 680px;
}

.page-hero .page-kpis {
  margin-top: var(--spacing-40);
  display: grid;
  gap: var(--spacing-24);
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

.page-kpi {
  padding: var(--spacing-24);
  border-radius: var(--radius-md);
  border: 1px solid rgba(33, 242, 255, 0.22);
  background: rgba(6, 12, 26, 0.65);
}

.page-kpi span {
  display: block;
  font-size: var(--font-size-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: var(--spacing-8);
}

.page-kpi strong {
  font-family: var(--font-en);
  font-size: clamp(1.8rem, 2.5vw, 2.3rem);
  letter-spacing: 0.05em;
}

.breadcrumb {
  background: rgba(6, 14, 30, 0.75);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-divider);
}

.breadcrumb .container {
  display: flex;
  gap: var(--spacing-12);
  align-items: center;
  padding: var(--spacing-16) 0;
  font-size: var(--font-size-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.breadcrumb a {
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-8);
}

.breadcrumb span {
  color: var(--text-title);
}

.page-content {
  padding: var(--spacing-48) 0 var(--spacing-64);
}

.page-content .layout {
  display: grid;
  gap: var(--grid-gap);
  grid-template-columns: minmax(0, 1fr);
}

@media (min-width: 1024px) {
  .page-content .layout.wide-sidebar {
    grid-template-columns: 1.65fr 1fr;
  }

  .page-content .layout.default {
    grid-template-columns: minmax(0, 3fr);
  }
}

.content-surface {
  padding: clamp(1.5rem, 2vw, 2.5rem);
  border-radius: var(--radius-lg);
  background: rgba(5, 12, 26, 0.78);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-soft);
  display: grid;
  gap: var(--spacing-24);
}

.content-surface h2,
.content-surface h3,
.content-surface h4 {
  color: var(--text-title);
}

.content-surface h2 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-12);
  position: relative;
  padding-left: var(--spacing-16);
}

.content-surface h2::before {
  content: "";
  position: absolute;
  left: 0;
  top: 12px;
  width: 4px;
  height: 20px;
  border-radius: var(--radius-pill);
  background: linear-gradient(180deg, var(--color-primary), var(--color-tertiary));
}

.content-surface h3 {
  font-size: var(--font-size-xl);
  margin-top: var(--spacing-24);
}

.content-surface ul,
.content-surface ol {
  padding-left: var(--spacing-24);
  display: grid;
  gap: var(--spacing-12);
}

.highlight-list {
  list-style: none;
  padding-left: 0;
  display: grid;
  gap: var(--spacing-12);
}

.highlight-list li {
  padding: var(--spacing-16);
  border-radius: var(--radius-md);
  background: rgba(21, 36, 70, 0.4);
  border: 1px solid rgba(33, 242, 255, 0.1);
  position: relative;
  padding-left: var(--spacing-40);
}

.highlight-list li::before {
  content: "";
  position: absolute;
  left: var(--spacing-16);
  top: 50%;
  transform: translateY(-50%);
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--color-secondary);
  box-shadow: 0 0 12px rgba(255, 122, 26, 0.6);
}

.sidebar {
  display: grid;
  gap: var(--spacing-24);
}

.sidebar-card {
  background: rgba(8, 18, 36, 0.82);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-md);
  padding: var(--spacing-24);
  display: grid;
  gap: var(--spacing-16);
}

.sidebar-card h4 {
  font-size: var(--font-size-md);
  color: var(--text-title);
}

.sidebar-links {
  list-style: none;
  display: grid;
  gap: var(--spacing-12);
}

.sidebar-links a {
  color: var(--text-muted);
  font-size: var(--font-size-sm);
}

.sidebar-links a:hover,
.sidebar-links a.is-active {
  color: var(--color-primary);
}

/* ==========================================================================
   8. Utility Classes
   ========================================================================== */
.text-muted { color: var(--text-muted); }
.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-secondary); }
.text-success { color: var(--color-success); }
.text-warning { color: var(--color-warning); }

.divider {
  height: 1px;
  background: var(--color-divider);
  width: 100%;
  margin: var(--spacing-24) 0;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-8);
  padding: var(--spacing-8) var(--spacing-16);
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
  font-size: var(--font-size-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.tagged-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-12);
}

.pulse {
  position: relative;
}

.pulse::after {
  content: "";
  position: absolute;
  inset: -18px;
  border-radius: inherit;
  background: radial-gradient(circle, rgba(33, 242, 255, 0.3), transparent 60%);
  opacity: 0;
  animation: pulse 2.8s infinite;
}

@keyframes pulse {
  0% {
    opacity: 0.7;
    transform: scale(0.85);
  }
  70% {
    opacity: 0;
    transform: scale(1.3);
  }
  100% {
    opacity: 0;
    transform: scale(1.4);
  }
}

/* ==========================================================================
   9. Forms
   ========================================================================== */
.input-group {
  display: grid;
  gap: var(--spacing-12);
}

label {
  font-size: var(--font-size-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

input,
select,
textarea {
  width: 100%;
  padding: var(--spacing-12) var(--spacing-16);
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: rgba(3, 9, 21, 0.75);
  color: var(--text-title);
  font-size: var(--font-size-sm);
  transition: border 0.25s ease, background 0.25s ease;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: rgba(33, 242, 255, 0.55);
  background: rgba(8, 18, 36, 0.95);
}

/* ==========================================================================
   10. Back-to-top button (created via JS)
   ========================================================================== */
#backToTopBtn {
  position: fixed;
  bottom: 28px;
  right: 24px;
  padding: var(--spacing-12) var(--spacing-16);
  border-radius: var(--radius-pill);
  background: linear-gradient(120deg, rgba(33, 242, 255, 0.9), rgba(20, 125, 255, 0.9));
  color: var(--text-inverse);
  border: none;
  font-size: var(--font-size-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 18px 40px rgba(20, 125, 255, 0.35);
  transition: transform 0.3s ease;
  z-index: 998;
}

#backToTopBtn:hover {
  transform: translateY(-4px);
}

@media (max-width: 768px) {
  section {
    padding: clamp(3.5rem, 8vw, 5rem) 0;
  }

  .header-cta {
    flex-wrap: wrap;
    gap: var(--spacing-12);
  }

  .site-footer__bottom {
    flex-direction: column;
  }
}