* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", "Microsoft Yahei", sans-serif;
  background: #f7f8ff;
  color: #253055;
}

h1,
h2,
h3,
h4 {
  margin: 0 0 8px;
}

p {
  margin: 0 0 8px;
  line-height: 1.5;
}

.app-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  padding: 24px 32px;
  background: linear-gradient(120deg, #fff4d9, #e8f5ff);
  border-bottom: 4px solid #ffe08a;
  gap: 16px;
}

.title-wrap h1 {
  font-size: 28px;
}

.subtitle {
  font-size: 16px;
  color: #5a6aa0;
}

.scoreboard {
  display: flex;
  gap: 16px;
}

.app-nav {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.nav-link {
  text-decoration: none;
  background: #ffffff;
  color: #2f56ff;
  padding: 8px 14px;
  border-radius: 14px;
  font-weight: 600;
  box-shadow: 0 4px 10px rgba(37, 48, 85, 0.12);
}

.nav-link.active {
  background: #2f56ff;
  color: #ffffff;
}

.score-item {
  background: #ffffff;
  border-radius: 16px;
  padding: 12px 18px;
  min-width: 120px;
  text-align: center;
  box-shadow: 0 6px 14px rgba(37, 48, 85, 0.12);
}

.score-label {
  font-size: 13px;
  color: #6b7bb5;
}

.score-value {
  display: block;
  font-size: 22px;
  font-weight: 700;
  color: #2f56ff;
}

.app-main {
  display: flex;
  flex-direction: column;
  gap: 24px;
  padding: 24px 32px 48px;
}

.app-footer {
  text-align: center;
  padding: 20px;
  background: #f0f2ff;
  color: #6b7bb5;
}

.primary-btn {
  border: none;
  border-radius: 14px;
  padding: 10px 18px;
  font-size: 16px;
  cursor: pointer;
  background: #ff8a3d;
  color: #fff;
  box-shadow: 0 6px 12px rgba(255, 138, 61, 0.35);
}

.primary-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.placeholder {
  padding: 18px;
  border: 2px dashed #d7dff8;
  border-radius: 16px;
  text-align: center;
  color: #8a97c8;
  background: #f9fbff;
}

@media (min-width: 960px) {
  .app-main {
    max-width: 1200px;
    margin: 0 auto;
  }
}