:root {
    --primary: #60a5fa;
    --accent: #f1f5f9;
    --bg: #0f172a;
    --card-bg: #1e293b;
    --text: #f1f5f9;
    --text-dim: #94a3b8;
    --border: #334155;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Inter', sans-serif; background-color: var(--bg); color: var(--text); line-height: 1.6; scroll-behavior: smooth; }
.container { max-width: 1000px; margin: 0 auto; padding: 0 20px; }

header { background: rgba(15, 23, 42, 0.95); position: sticky; top: 0; z-index: 1000; border-bottom: 1px solid var(--border); backdrop-filter: blur(8px); }
nav { display: flex; justify-content: space-between; align-items: center; padding: 1rem 0; }
.logo { font-size: 1.5rem; font-weight: 800; color: var(--primary); }
nav ul { display: flex; list-style: none; gap: 20px; }
nav a { text-decoration: none; color: var(--text-dim); font-size: 0.9rem; transition: 0.3s; }
nav a:hover { color: var(--primary); }

.hero { padding: 80px 0 40px; }
h1 { font-size: 3.5rem; margin-bottom: 0.5rem; }
.objective { margin-bottom: 10px; color: var(--primary); }
.divider { border: 0; height: 1px; background: var(--border); margin: 30px 0; }
.intro-text { color: var(--text-dim); margin-bottom: 1rem; }

.video-section { background: #0f172a; padding: 40px 0; }
.video-wrapper { max-width: 750px; margin: 0 auto; padding: 0 20px; }
.video-container { position: relative; padding-bottom: 56.25%; height: 0; border-radius: 12px; overflow: hidden; box-shadow: 0 10px 30px rgba(0,0,0,0.5); }
.video-container iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }

.content-block { padding: 60px 0; border-bottom: 1px solid var(--border); }
h2 { color: var(--primary); margin-bottom: 25px; }
h3 { margin-bottom: 15px; }
ul, ol { list-style-position: inside; margin-bottom: 1rem; }
li { margin-bottom: 8px; }

.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.card { background: var(--card-bg); padding: 25px; border-radius: 12px; margin-top: 30px; border: 1px solid var(--border); }
.highlight { border-color: var(--primary); }

.feature-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 15px; margin-top: 20px; }
.feature-item { background: #192746; padding: 15px; border-radius: 8px; border: 1px solid var(--border); font-size: 0.9rem; }

.formula-card { background: var(--card-bg); padding: 30px; border-radius: 12px; margin-top: 30px; }
.formula { background: #192746; padding: 20px; border-radius: 8px; margin: 15px 0; color: var(--accent); font-family: monospace; overflow-x: auto; }

footer { text-align: center; padding: 50px 0; color: var(--text-dim); }