/* ==========================================================================
   Skyline Support — base, tokens, resets
   ========================================================================== */

/* Dark is the default look (site defaults to dark mode); light is the opt-out. */
:root {
  --bg: #0A0A0A;
  --surface: #171717;
  --border: #262626;
  --text: #FAFAFA;
  --text2: #A3A3A3;
  --text3: #737373;
  --accent: #3B82F6;
  --accent-hover: #60A5FA;
  --accent-tint: rgba(30, 58, 138, 0.35);
  --error: #DC2626;

  --font-sans: ui-sans-serif, -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial,
    'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;

  --container-max: 1200px;
  --section-pad-y: clamp(4rem, 8vw, 7rem);
  --container-pad-x: clamp(1.25rem, 4vw, 2rem);
}

:root[data-theme="light"] {
  --bg: #FFFFFF;
  --surface: #FAFAFA;
  --border: #E5E7EB;
  --text: #0A0A0A;
  --text2: #525252;
  --text3: #737373;
  --accent: #1E40AF;
  --accent-hover: #1E3A8A;
  --accent-tint: #EFF6FF;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: auto; /* smooth-scroll is handled in JS so we control the header offset */
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.5;
  min-height: 100vh;
  transition: background 150ms ease, color 150ms ease;
}

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

a {
  color: inherit;
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-pad-x);
}

/* Visible focus states — WCAG 2.1 AA */
a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ==========================================================================
   Buttons & links
   ========================================================================== */

.btn {
  display: inline-block;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9375rem;
  border-radius: 6px;
  cursor: pointer;
  transition: background 150ms ease, border-color 150ms ease, color 150ms ease;
  border: none;
  text-align: center;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  padding: 9px 18px;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-lg {
  padding: 13px 26px;
  font-size: 1rem;
}

.link-underline {
  color: var(--text);
  text-decoration: none;
  font-size: 1rem;
  font-weight: 600;
  border-bottom: 1px solid var(--border);
  padding-bottom: 2px;
}

/* ==========================================================================
   Header
   ========================================================================== */

.header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: 72px;
  display: flex;
  align-items: center;
  background: var(--bg);
  border-bottom: 1px solid transparent;
  transition: border-color 150ms ease;
}

.header.scrolled {
  border-bottom-color: var(--border);
}

.header-inner {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 1.0625rem;
  letter-spacing: -0.01em;
}

.logo-mark {
  display: inline-block;
  width: 11px;
  height: 11px;
  background: var(--accent);
  transform: rotate(45deg);
  border-radius: 2px;
  flex-shrink: 0;
}

.logo-mark-footer {
  background: #3B82F6;
}

.nav {
  display: none;
  gap: 2rem;
}

.nav-link {
  color: var(--text2);
  text-decoration: none;
  font-size: 0.9375rem;
  transition: color 150ms ease;
}

.nav-link:hover {
  color: var(--text);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.header-cta {
  display: none;
}

.hamburger {
  display: flex;
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  width: 38px;
  height: 38px;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-direction: column;
  gap: 4px;
}

.hamburger span {
  width: 16px;
  height: 2px;
  background: var(--text);
}

/* Language switcher (desktop dropdown) */

.lang-switcher {
  position: relative;
  display: none;
}

.lang-button {
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 0.8125rem;
  color: var(--text2);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
}

.lang-menu {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 4px;
  min-width: 88px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
  z-index: 60;
}

.lang-option {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 8px 10px;
  border-radius: 6px;
  font-size: 0.875rem;
  color: var(--text);
  cursor: pointer;
}

.lang-option:hover {
  background: var(--accent-tint);
}

/* Mobile nav sheet */

.mobile-nav {
  position: absolute;
  top: 72px;
  left: 0;
  right: 0;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 1.25rem var(--container-pad-x);
  flex-direction: column;
  gap: 1rem;
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08);
}

/* `.mobile-nav[hidden]` must fall through to the UA `display:none` — scope the
   flex layout to the visible state so the native `hidden` attribute keeps working. */
.mobile-nav:not([hidden]) {
  display: flex;
}

.mobile-nav-link {
  color: var(--text);
  text-decoration: none;
  font-size: 1rem;
}

.mobile-lang-row {
  display: flex;
  gap: 8px;
  padding-top: 0.5rem;
  border-top: 1px solid var(--border);
  margin-top: 0.25rem;
}

.mobile-lang-option {
  flex: 1;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: none;
  color: var(--text);
  cursor: pointer;
}

.mobile-nav-cta {
  text-align: center;
  padding: 10px;
}

/* ==========================================================================
   Hero
   ========================================================================== */

.hero {
  min-height: auto;
  display: flex;
  align-items: center;
  padding: var(--section-pad-y) var(--container-pad-x);
  position: relative;
  overflow: hidden;
}

.hero-sentinel {
  position: absolute;
  top: 0;
  left: 0;
  width: 1px;
  height: 1px;
}

.hero-grid-accent {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -55%);
  width: min(900px, 90%);
  height: 280px;
  background-image:
    repeating-linear-gradient(0deg, var(--accent-tint) 0px, var(--accent-tint) 1px, transparent 1px, transparent 48px),
    repeating-linear-gradient(90deg, var(--accent-tint) 0px, var(--accent-tint) 1px, transparent 1px, transparent 48px);
  opacity: 0.5;
  pointer-events: none;
}

.hero-content {
  max-width: 900px;
  margin: 0 auto;
  text-align: center;
  position: relative;
  z-index: 1;
}

.trust-badge {
  display: inline-block;
  color: var(--accent);
  background: var(--accent-tint);
  border: 1px solid var(--accent);
  border-radius: 999px;
  padding: 6px 16px;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  margin: 0 0 1.5rem;
}

.hero-headline {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0 0 1.25rem;
}

.hero-subhead {
  font-size: 1.125rem;
  color: var(--text2);
  line-height: 1.6;
  margin: 0 auto 2rem;
  max-width: 680px;
}

.hero-cta-row {
  display: flex;
  gap: 1.25rem;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
}

/* ==========================================================================
   Sections — shared
   ========================================================================== */

.section {
  padding: var(--section-pad-y) var(--container-pad-x);
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 300ms ease-out, transform 300ms ease-out;
}

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

.section-surface {
  background: var(--surface);
}

.section-head {
  max-width: 700px;
  margin: 0 auto 3rem;
  text-align: center;
}

.section-head-plain {
  max-width: none;
}

.eyebrow {
  color: var(--accent);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.section-title {
  font-size: clamp(2rem, 3.5vw, 2.75rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.015em;
  margin: 0 0 0.75rem;
}

.section-head-plain .section-title {
  margin: 0;
}

.section-subtitle {
  color: var(--text2);
  font-size: 1.0625rem;
  margin: 0;
}

.title-underline {
  width: 48px;
  height: 3px;
  background: var(--accent);
  margin: 1.5rem auto 0;
  border-radius: 2px;
}

.title-underline-left {
  margin: 1.5rem 0 0;
}

/* ==========================================================================
   Services
   ========================================================================== */

.grid-3 {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

.service-card {
  padding: 32px;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 12px;
  transition: border-color 150ms ease, transform 150ms ease, box-shadow 150ms ease;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.service-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  box-shadow: 0 16px 32px rgba(0, 0, 0, 0.08);
}

.service-num {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: var(--accent-tint);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.875rem;
  letter-spacing: 0.02em;
  margin-bottom: 1.25rem;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 0.625rem;
}

.card-desc {
  color: var(--text2);
  line-height: 1.6;
  margin: 0 0 1.25rem;
}

.card-bullets {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.card-bullets li {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  color: var(--text2);
  font-size: 0.9375rem;
  line-height: 1.5;
}

.card-bullets .check {
  color: var(--accent);
  flex-shrink: 0;
}

/* ==========================================================================
   Pricing
   ========================================================================== */

.pricing-card {
  padding: 32px;
  background: var(--bg);
  border-radius: 12px;
  position: relative;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
  transition: transform 150ms ease, box-shadow 150ms ease;
}

.pricing-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 32px rgba(0, 0, 0, 0.1);
}

.pricing-card-bar {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent-hover));
}

.pricing-card .card-title {
  margin: 0.5rem 0 0.625rem;
}

.pricing-card .card-bullets {
  margin: 0 0 1.5rem;
}

.pricing-quote-btn {
  width: 100%;
  background: none;
  border: 1px solid var(--accent);
  color: var(--accent);
  padding: 11px;
  border-radius: 6px;
  font-size: 0.9375rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 150ms ease;
}

.pricing-quote-btn:hover {
  background: var(--accent-tint);
}

.pricing-footer-note {
  text-align: center;
  color: var(--text2);
  margin: 2.5rem 0 0;
  font-size: 0.9375rem;
}

/* ==========================================================================
   Why Skyline
   ========================================================================== */

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

.why-card {
  padding: 28px;
  border-radius: 12px;
  background: var(--surface);
  border: 1px solid var(--border);
}

.why-icon {
  width: 48px;
  height: 48px;
  border-radius: 10px;
  background: var(--accent-tint);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
}

.why-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 0.625rem;
}

.why-body {
  color: var(--text2);
  line-height: 1.6;
  margin: 0;
}

/* ==========================================================================
   About
   ========================================================================== */

.about-layout {
  display: flex;
  flex-direction: column;
  gap: 3rem;
}

.about-col-left,
.about-col-right {
  flex: 1;
}

.about-sticky {
  position: static;
  top: 100px;
}

.about-col-right {
  max-width: 620px;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.about-paragraph {
  line-height: 1.7;
  color: var(--text2);
  margin: 0;
  font-size: 1.0625rem;
}

/* ==========================================================================
   Contact
   ========================================================================== */

.contact-layout {
  display: flex;
  flex-direction: column-reverse;
  gap: 3rem;
}

.contact-info {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.contact-label {
  color: var(--text3);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: 0.75rem;
  margin-bottom: 0.375rem;
}

.contact-value {
  color: var(--text);
  font-size: 1.0625rem;
}

.contact-form-panel {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
}

.form-success {
  background: var(--accent-tint);
  border: 1px solid var(--accent);
  border-radius: 8px;
  padding: 1.5rem;
  color: var(--text);
  font-size: 1rem;
  line-height: 1.6;
}

#contact-form {
  flex-direction: column;
  gap: 1.125rem;
}

/* Same `[hidden]` cascade concern as .mobile-nav above. */
#contact-form:not([hidden]) {
  display: flex;
}

.form-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0;
}

.form-field label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  margin-bottom: 0.375rem;
}

.form-field input,
.form-field select,
.form-field textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
  font-size: 1rem;
  font-family: inherit;
}

.form-field textarea {
  resize: vertical;
}

.form-field input:focus-visible,
.form-field select:focus-visible,
.form-field textarea:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-tint);
}

.form-field input[aria-invalid="true"],
.form-field textarea[aria-invalid="true"] {
  border-color: var(--error);
}

.form-error {
  color: var(--error);
  font-size: 0.8125rem;
  margin-top: 0.375rem;
}

.form-submit {
  width: 100%;
  padding: 13px;
  font-size: 1rem;
  border-radius: 8px;
  align-self: flex-start;
}

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
  background: #0A0A0A;
  color: #FAFAFA;
  padding: clamp(3rem, 6vw, 4.5rem) var(--container-pad-x) 2rem;
  border-top: 3px solid var(--accent);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.0625rem;
  margin-bottom: 0.75rem;
}

.footer-tagline {
  color: #A3A3A3;
  font-size: 0.9375rem;
  line-height: 1.6;
  margin: 0;
  max-width: 240px;
}

.footer-col-title {
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #737373;
  margin-bottom: 1rem;
}

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

.footer-link,
.footer-static {
  color: #D4D4D4;
  text-decoration: none;
  font-size: 0.9375rem;
}

.footer-bottom {
  border-top: 1px solid #262626;
  padding-top: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-copyright {
  color: #737373;
  font-size: 0.875rem;
}

.footer-bottom-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.footer-lang-option {
  background: none;
  border: 1px solid #262626;
  color: #D4D4D4;
  border-radius: 6px;
  padding: 5px 9px;
  font-size: 0.8125rem;
  cursor: pointer;
}

.theme-toggle {
  background: none;
  border: 1px solid #262626;
  border-radius: 6px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

/* ==========================================================================
   Responsive breakpoints — 640 / 1024 / 1280
   ========================================================================== */

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

  .grid-why {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .nav {
    display: flex;
  }

  .lang-switcher {
    display: block;
  }

  .header-cta {
    display: inline-block;
  }

  .hamburger {
    display: none;
  }

  .hero {
    min-height: calc(100vh - 72px);
  }

  .grid-3 {
    grid-template-columns: repeat(3, 1fr);
  }

  .about-layout {
    flex-direction: row;
  }

  .about-sticky {
    position: sticky;
  }

  .contact-layout {
    flex-direction: row;
  }

  .form-submit {
    width: auto;
  }

  .footer-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

@media (min-width: 1280px) {
  .grid-why {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* ==========================================================================
   Reduced motion
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
  .section {
    transition: none;
  }
  .header,
  .btn,
  .nav-link,
  .service-card,
  .pricing-card,
  .pricing-quote-btn,
  .lang-option {
    transition: none;
  }
}