* {
  box-sizing: border-box;
}

html {
  font-size: 100%;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  color: #1f2933;
  background: #eef4f8;
}

a {
  color: #0056b3;
  text-decoration: none;
}

a:hover,
a:focus {
  text-decoration: underline;
}

.page {
  width: min(960px, calc(100% - 24px));
  margin: 24px auto;
  overflow: hidden;
  background: #ffffff;
  border: 7px solid #2a7db8;
  border-radius: 20px;
  box-shadow: 7px 7px 12px rgba(0, 0, 0, 0.25);
}

.site-header {
  padding: 16px 20px 10px;
}

.logo {
  display: block;
  max-width: 100%;
  height: auto;
}

.top-nav,
.bottom-nav {
  margin: 0 20px;
  padding: 12px 0;
  text-align: center;
  border-top: 2px solid #0056b3;
  border-bottom: 2px solid #0056b3;
}

.top-nav span,
.top-nav strong {
  margin-left: 10px;
}

.top-nav span {
  color: #777;
}

.top-nav strong {
  color: #336666;
}

.content {
  width: min(880px, 100%);
  margin: 0 auto;
  padding: 18px 20px 28px;
}

h1 {
  margin: 8px 0 18px;
  text-align: center;
  font-size: clamp(1.35rem, 2.5vw, 2rem);
  line-height: 1.25;
  color: #174f7a;
}

.video-section {
  margin-bottom: 24px;
}

.video-wrapper {
  position: relative;
  width: min(800px, 100%);
  margin: 0 auto;
  aspect-ratio: 16 / 9;
  background: #000;
  border-radius: 12px;
  overflow: hidden;
}

.video-wrapper iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.youtube-note {
  max-width: 800px;
  margin: 12px auto 0;
  padding: 12px 14px;
  font-size: 0.9rem;
  line-height: 1.5;
  color: #333;
  background: #f4f7fb;
  border-left: 4px solid #2a7db8;
  border-radius: 8px;
}

.image-block {
  margin: 26px 0;
  text-align: center;
}

.image-block img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
}

.site-footer {
  padding: 16px 20px 18px;
  text-align: center;
  font-size: 0.9rem;
  background: #ededed;
}

.site-footer p {
  margin: 0 0 8px;
}

.credits {
  font-size: 0.78rem;
  line-height: 1.45;
}

@media (max-width: 640px) {
  .page {
    width: calc(100% - 12px);
    margin: 6px auto;
    border-width: 4px;
    border-radius: 14px;
  }

  .site-header,
  .content,
  .site-footer {
    padding-left: 14px;
    padding-right: 14px;
  }

  .top-nav,
  .bottom-nav {
    margin-left: 14px;
    margin-right: 14px;
  }

  .top-nav span,
  .top-nav strong {
    display: block;
    margin: 4px 0 0;
  }
}