* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', Tahoma, sans-serif;
  background: #f4f6f8;
  color: #222;
  line-height: 1.6;
}

header {
  background: #1f2937;
  padding: 1rem 2rem;
}

nav ul {
  display: flex;
  gap: 1.5rem;
  list-style: none;
  flex-wrap: wrap;
}

nav a {
  color: #e5e7eb;
  text-decoration: none;
  font-weight: 500;
  padding: 0.4rem 0.8rem;
  border-radius: 6px;
  transition: background 0.2s;
}

nav a:hover,
nav a.active {
  background: #374151;
  color: #fff;
}

main {
  max-width: 1000px;
  margin: 2rem auto;
  padding: 0 1.5rem;
}

h1 {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: #111827;
}

h2 {
  margin: 1.5rem 0 0.8rem;
  color: #1f2937;
}

p {
  margin-bottom: 1rem;
}

.hero {
  background: #fff;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.06);
}

.btn {
  display: inline-block;
  background: #2563eb;
  color: #fff;
  padding: 0.7rem 1.4rem;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background 0.2s;
}

.btn:hover {
  background: #1d4ed8;
}

.english-btn {
  margin-top: 1.5rem;
}

.card {
  background: #fff;
  padding: 1.5rem;
  border-radius: 10px;
  margin-bottom: 1.2rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

/* Форма авторизации */
.auth-box {
  max-width: 400px;
  background: #fff;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}

.auth-box label {
  display: block;
  margin-bottom: 0.4rem;
  font-weight: 500;
}

.auth-box input {
  width: 100%;
  padding: 0.6rem;
  margin-bottom: 1rem;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  font-size: 1rem;
}

.auth-box .error {
  color: #dc2626;
  font-size: 0.9rem;
  margin-bottom: 1rem;
  display: none;
}

.hidden {
  display: none !important;
}

/* Видео */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.video-item {
  background: #fff;
  padding: 1rem;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.video-item iframe {
  width: 100%;
  aspect-ratio: 16 / 9;
  border: none;
  border-radius: 8px;
}

footer {
  text-align: center;
  padding: 2rem;
  color: #6b7280;
  font-size: 0.9rem;
}