:root {
    --navy: #0b2545;
    --blue: #1663c7;
    --sky: #e8f1fc;
    --accent: #00b4d8;
    --orange: #f4772e;
    --text: #2b3445;
    --gray: #6b7688;
    --light: #f7f9fc;
    --white: #ffffff;
    --radius: 14px;
  }
  * { margin: 0; padding: 0; box-sizing: border-box; }
  html { scroll-behavior: smooth; }
  body {
    font-family: "Segoe UI", "Helvetica Neue", Arial, sans-serif;
    color: var(--text);
    background: var(--white);
    line-height: 1.65;
  }

  /* ---------- NAV ---------- */
  header {
    position: sticky; top: 0; z-index: 100;
    background: rgba(11,37,69,0.97);
    backdrop-filter: blur(6px);
    box-shadow: 0 2px 12px rgba(0,0,0,.25);
  }
  nav {
    max-width: 1160px; margin: auto;
    display: flex; align-items: center; justify-content: space-between;
    padding: 0.9rem 1.5rem;
  }
  .logo { display: flex; align-items: center; gap: .6rem; color: #fff; font-weight: 700; font-size: 1.25rem; text-decoration: none; }
  .logo-sphere {
    width: 26px; height: 26px; border-radius: 50%;
    background: radial-gradient(circle at 35% 30%, #7fd4ff, var(--accent) 55%, var(--blue));
    box-shadow: 0 0 10px rgba(0,180,216,.6);
  }
  nav ul { display: flex; list-style: none; gap: 1.4rem; flex-wrap: wrap; }
  nav a.navlink { color: #cfe0f5; text-decoration: none; font-size: .92rem; transition: color .2s; }
  nav a.navlink:hover { color: var(--accent); }

  /* ---------- HERO ---------- */
  .hero {
    background: linear-gradient(150deg, var(--navy) 0%, #123a6e 55%, #1663c7 100%);
    color: #fff;
    padding: 5.5rem 1.5rem 6rem;
    position: relative;
    overflow: hidden;
  }
  .hero::before, .hero::after {
    content: ""; position: absolute; border-radius: 50%;
    background: radial-gradient(circle at 35% 30%, rgba(127,212,255,.35), rgba(0,180,216,.12) 60%, transparent 75%);
  }
  .hero::before { width: 420px; height: 420px; right: -90px; top: -60px; }
  .hero::after  { width: 240px; height: 240px; right: 260px; bottom: -80px; opacity: .7; }
  .hero-inner { max-width: 1160px; margin: auto; position: relative; z-index: 2; }
  .hero .tagline {
    display: inline-block; background: rgba(0,180,216,.18); border: 1px solid rgba(0,180,216,.5);
    color: #9fe8ff; padding: .35rem 1rem; border-radius: 100px; font-size: .85rem; letter-spacing: .06em;
    text-transform: uppercase; margin-bottom: 1.4rem;
  }
  .hero h1 { font-size: clamp(2rem, 4.6vw, 3.4rem); line-height: 1.15; max-width: 820px; margin-bottom: 1.2rem; }
  .hero h1 span { color: var(--accent); }
  .hero p.lead { font-size: 1.15rem; max-width: 720px; color: #d7e5f7; margin-bottom: 2.2rem; }
  .btn {
    display: inline-block; padding: .85rem 1.9rem; border-radius: 100px;
    font-weight: 600; text-decoration: none; font-size: 1rem; transition: transform .15s, box-shadow .15s;
  }
  .btn-primary { background: var(--accent); color: #06283d; box-shadow: 0 6px 18px rgba(0,180,216,.4); margin-right: .8rem; }
  .btn-ghost { border: 1.5px solid #7fa8d8; color: #eaf3fd; }
  .btn:hover { transform: translateY(-2px); }

  .hero-stats {
    display: flex; gap: 2.6rem; flex-wrap: wrap; margin-top: 3.2rem;
  }
  .stat b { display: block; font-size: 1.9rem; color: var(--accent); }
  .stat span { font-size: .88rem; color: #b9cde8; }

  /* ---------- SECTIONS ---------- */
  section { padding: 4.5rem 1.5rem; }
  .container { max-width: 1160px; margin: auto; }
  .kicker { color: var(--blue); font-weight: 700; text-transform: uppercase; letter-spacing: .09em; font-size: .8rem; }
  h2.section-title { font-size: clamp(1.6rem, 3vw, 2.3rem); color: var(--navy); margin: .4rem 0 1rem; }
  p.section-intro { max-width: 760px; color: var(--gray); font-size: 1.05rem; margin-bottom: 2.5rem; }

  /* Why spheres */
  .why { background: var(--light); }
  .why-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 1.4rem; }
  .why-card {
    background: #fff; border-radius: var(--radius); padding: 1.6rem;
    border: 1px solid #e3eaf4; box-shadow: 0 3px 12px rgba(11,37,69,.05);
  }
  .why-card .icon { font-size: 1.8rem; margin-bottom: .6rem; }
  .why-card h3 { color: var(--navy); font-size: 1.05rem; margin-bottom: .4rem; }
  .why-card p { font-size: .93rem; color: var(--gray); }

  /* Challenges */
  .challenge {
    display: grid; grid-template-columns: 64px 1fr; gap: 1.4rem;
    background: #fff; border: 1px solid #e3eaf4; border-radius: var(--radius);
    padding: 1.9rem 2rem; margin-bottom: 1.6rem;
    box-shadow: 0 4px 16px rgba(11,37,69,.06);
  }
  .challenge .num {
    width: 56px; height: 56px; border-radius: 50%;
    background: linear-gradient(140deg, var(--blue), var(--accent));
    color: #fff; font-size: 1.4rem; font-weight: 700;
    display: flex; align-items: center; justify-content: center;
    box-shadow: 0 4px 12px rgba(22,99,199,.35);
  }
  .challenge h3 { color: var(--navy); font-size: 1.25rem; margin-bottom: .7rem; }
  .challenge h4 { color: var(--blue); font-size: .95rem; margin: .9rem 0 .25rem; }
  .challenge p { font-size: .97rem; color: var(--text); }
  .tag {
    display: inline-block; background: var(--sky); color: var(--blue);
    font-size: .74rem; font-weight: 700; padding: .2rem .7rem; border-radius: 100px;
    margin: .8rem .3rem 0 0; letter-spacing: .03em;
  }

  /* Roadmap / summary */
  .roadmap { background: linear-gradient(150deg, var(--navy), #143d72); color: #fff; }
  .roadmap h2 { color: #fff; }
  .roadmap .kicker { color: var(--accent); }
  .roadmap p.section-intro { color: #c6d8ef; }
  .roadmap-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.4rem; }
  .roadmap-card {
    background: rgba(255,255,255,.07); border: 1px solid rgba(255,255,255,.15);
    border-radius: var(--radius); padding: 1.8rem;
  }
  .roadmap-card .step { color: var(--accent); font-weight: 700; font-size: .82rem; letter-spacing: .08em; text-transform: uppercase; }
  .roadmap-card h3 { margin: .5rem 0 .6rem; font-size: 1.15rem; }
  .roadmap-card p { color: #cdddf2; font-size: .94rem; }

  /* CTA */
  .cta { text-align: center; background: var(--light); }
  .cta h2 { font-size: clamp(1.5rem, 3vw, 2.1rem); color: var(--navy); margin-bottom: .8rem; }
  .cta p { color: var(--gray); max-width: 640px; margin: 0 auto 1.8rem; }

  /* Footer */
  footer { background: var(--navy); color: #9db4d4; padding: 2.2rem 1.5rem; text-align: center; font-size: .87rem; }
  footer a { color: var(--accent); text-decoration: none; }

  @media (max-width: 640px) {
    nav ul { display: none; }
    .challenge { grid-template-columns: 1fr; }
    .challenge .num { width: 48px; height: 48px; font-size: 1.2rem; }
  }