/* Root Variables */
:root {
  --bg: #f8fafc;
  --bg-soft: #ffffff;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --brand: #0ea5e9;
  --brand-2: #22d3ee;
  --ring: rgba(14,165,233,.22);
  --container: 1100px;
  --radius: 16px;
  --shadow: 0 16px 40px rgba(15,23,42,.08);
  --shadow-soft: 0 8px 20px rgba(15,23,42,.06);
}

/* Base Styles */
* { 
  box-sizing: border-box; 
}

html { 
  scroll-behavior: smooth; 
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  color: var(--text);
  background:
    radial-gradient(1200px 600px at 10% -10%, rgba(14,165,233,.15), rgba(34,211,238,.12) 35%, transparent 60%),
    radial-gradient(1200px 600px at 110% 10%, rgba(34,211,238,.12), transparent 60%),
    var(--bg);
  background-attachment: fixed;
  line-height: 1.55;
  font-size: 20px;
}

/* Links and Media */
a { 
  color: inherit; 
  text-decoration: none; 
}

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

/* Container */
.container { 
  width: min(100%, var(--container)); 
  margin-inline: auto; 
  padding-inline: 1.2rem; 
}

/* Header */
header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: saturate(140%) blur(10px);
  -webkit-backdrop-filter: saturate(140%) blur(10px);
  background: rgba(255,255,255,.85);
  border-bottom: 1px solid rgba(15,23,42,.08);
}

@supports not ((backdrop-filter: blur(10px)) or (-webkit-backdrop-filter: blur(10px))) {
  header { 
    background: #ffffff; 
  }
}

nav { 
  display: flex; 
  align-items: center; 
  justify-content: space-between; 
  gap: 1rem; 
  min-height: 64px; 
}

.logo { 
  font-weight: 800;
  font-size: 1.4rem;
  letter-spacing: .2px; 
}

.logo span { 
  color: var(--brand); 
}

@supports (-webkit-background-clip: text) or (background-clip: text) {
  .logo span {
    background: linear-gradient(90deg, var(--brand), var(--brand-2));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
  }
}

.nav-links { 
  display: flex; 
  gap: .6rem; 
  list-style: none; 
  padding: 0; 
  margin: 0; 
}

.nav-links a { 
  padding: .8rem 1.2rem;
  border-radius: 12px; 
  color: var(--muted); 
  font-weight: 600; 
  font-size: 1.1rem;
}

.nav-links a:hover, 
.nav-links a.active { 
  color: var(--text); 
  background: rgba(14,165,233,.14); 
}

.menu-toggle { 
  display: none; 
  border: 1px solid rgba(14,165,233,.5); 
  border-radius: 12px; 
  padding: .6rem .8rem; 
  background: #fff; 
}

/* Sections */
.section { 
  padding-block: clamp(4rem, 8vw, 8rem);
  margin-bottom: 2rem;
}

.section-title { 
  font-size: clamp(2rem, 4vw, 2.6rem);
  margin: 0 0 1.5rem;
}

/* Hero Section */
.hero {
  display: grid;
  grid-template-columns: 1.2fr .8fr;
  gap: 13rem;
  align-items: center;
}

.hero h1 { 
  font-size: clamp(2.4rem, 6vw, 3.4rem);
  margin: 0 0 .8rem;
}

.hero h1 span { 
  color: var(--brand); 
}

.hero p { 
  font-size: clamp(1.2rem, 2.3vw, 1.3rem);
}

.actions { 
  display: flex;
  gap: .9rem;
  flex-wrap: wrap;
  margin-top: 1.2rem;
}

/* Buttons */
.btn { 
  padding: 1rem 1.1rem;
  border-radius: 14px;
  border: 1px solid var(--brand);
  font-weight: 700;
  box-shadow: var(--shadow-soft);
  min-height: 44px;
}

.btn-primary { 
  background: linear-gradient(90deg,var(--brand),var(--brand-2));
  color: #fff;
}

.btn-outline { 
  background: #fff;
  color: var(--text);
}

/* Phone Mockup */
.phone { 
  width: 340px;
  margin-left: auto;
  margin-right: auto;
  aspect-ratio: 9/19.5;
  border-radius: 28px;
  background: #0b1220;
  box-shadow: var(--shadow);
  position: relative;
  border: 6px solid #0b1220;
  overflow: hidden;
}

.phone-top,
.phone-bottom { 
  position: absolute;
  left: 0;
  right: 0;
  height: 10px;
  background: transparent;
}

.phone-top { 
  top: 0; 
}

.phone-bottom { 
  bottom: 0; 
}

.phone-screen { 
  position: absolute;
  inset: 6px;
  border-radius: 22px;
  background: #000;
  overflow: hidden;
}

/* Overview Section */
.grid-2 { 
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 4rem;
  align-items: start;
}

.muted { 
  color: var(--muted); 
}

.card { 
  background: var(--card);
  border: 1px solid rgba(14,165,233,.35);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
  padding: 1.1rem;
}

/* Features Section */
.features-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 340px;
  gap: 2rem;
  align-items: start;
}

.phone-container {
  position: sticky;
  top: 90px;
  width: 340px;
  left: 0;
  right: 0;
  margin: 0 auto;
}

.feature-item { 
  background: var(--card);
  border: 1px solid rgba(14,165,233,.35);
  border-radius: var(--radius);
  padding: .9rem 1rem;
  cursor: pointer;
  box-shadow: var(--shadow-soft);
  transition: transform .15s ease, box-shadow .15s ease, border-color .15s;
}

.feature-item:hover { 
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.feature-item.active { 
  border-color: var(--brand);
  box-shadow: var(--shadow);
}

.feature-header { 
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.feature-title { 
  margin: .1rem 0;
  font-size: 1.2rem;
  font-weight: 700;
}

.feature-description { 
  color: var(--muted);
  display: none;
  margin-top: .4rem;
}

.feature-arrow { 
  display: inline-block;
  transition: transform .25s ease;
}

.feature-item.open .feature-arrow { 
  transform: rotate(180deg);
}

/* Challenges & Experience */
.grid-4 { 
  display: grid;
  grid-template-columns: repeat(4, minmax(0,1fr));
  gap: 1rem;
}

.grid-3 { 
  display: grid;
  grid-template-columns: repeat(3, minmax(0,1fr));
  gap: 1rem;
}

.box { 
  background: var(--card);
  border: 1px solid rgba(14,165,233,.35);
  border-radius: var(--radius);
  padding: 1rem;
  box-shadow: var(--shadow-soft);
}

.box h3 { 
  font-size: 1.3rem;
  margin: .3rem 0 .5rem;
}

/* Footer */
footer { 
  margin-top: 11rem;
  border-top: 1px solid rgba(14,165,233,.35);
  padding-block: 2rem;
  text-align: center;
  background: var(--bg-soft);
}

/* Utilities */
.fade-up { 
  opacity: 0;
  transform: translateY(12px);
  transition: opacity .6s ease, transform .6s ease;
}

.fade-up.appear { 
  opacity: 1;
  transform: none;
}

/* Responsive */
@media (max-width: 960px) {
  .hero { 
    grid-template-columns: 1fr;
  }
  
  .grid-2 { 
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}