:root {
  --bg: #eef3f8;
  --bg-deep: #dbe7f4;
  --card: #ffffff;
  --text: #102039;
  --text-soft: #5a6f8a;
  --line: #d9e5f3;
  --primary: #0f6bff;
  --primary-strong: #0054de;
  --max-width: 430px;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  min-height: 100%;
  font-family: "SF Pro Display", "PingFang SC", "Noto Sans SC", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 16% 2%, rgba(15, 107, 255, 0.18), transparent 42%),
    linear-gradient(160deg, var(--bg), var(--bg-deep));
}

.app {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: max(12px, env(safe-area-inset-top)) 12px max(16px, env(safe-area-inset-bottom));
  display: grid;
  gap: 12px;
}

.topbar {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  justify-content: space-between;
  flex-wrap: nowrap;
}

.topbar-actions {
  display: flex;
  gap: 8px;
  align-items: center;
  justify-content: flex-start;
  flex-wrap: wrap;
  min-width: 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 700;
  font-size: 0.9rem;
  border: 1px solid transparent;
  padding: 0 14px;
  white-space: nowrap;
}

.btn-primary {
  color: #fff;
  background: linear-gradient(135deg, var(--primary), var(--primary-strong));
  box-shadow: 0 8px 18px rgba(15, 107, 255, 0.24);
}

.btn-soft {
  color: #234a7b;
  background: #f4f8ff;
  border-color: #d6e4f8;
}

.title-card {
  background: linear-gradient(145deg, #0b1f3b, #16457f 66%, #1569b8);
  color: #f5f9ff;
  border-radius: 16px;
  padding: 14px;
  box-shadow: 0 14px 24px rgba(14, 37, 67, 0.24);
}

.title-card h1 {
  margin: 0;
  font-size: 1.2rem;
}

.title-card p {
  margin: 6px 0 0;
  font-size: 0.88rem;
  opacity: 0.92;
  line-height: 1.5;
}

.video-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 12px;
  box-shadow: 0 10px 22px rgba(23, 50, 83, 0.1);
}

.video-list {
  display: grid;
  gap: 12px;
}

.video-card h2 {
  margin: 0 0 8px;
  font-size: 0.96rem;
}

.video-card p {
  margin: 0 0 10px;
  font-size: 0.85rem;
  color: var(--text-soft);
  line-height: 1.55;
}

video {
  width: 100%;
  display: block;
  border-radius: 12px;
  border: 1px solid #d8e5f3;
  background: #000;
}

.tip {
  font-size: 0.82rem;
  color: var(--text-soft);
  text-align: center;
  line-height: 1.55;
}

@media (max-width: 420px) {
  .topbar {
    flex-wrap: wrap;
  }

  .topbar-actions {
    width: 100%;
    flex-direction: column;
    align-items: stretch;
  }
}