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

body {
  background: radial-gradient(circle at 10% 20%, #0a0f1e, #02040a);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0 1.5rem 2rem 1.5rem;
  position: relative;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  top: -15%;
  left: -5%;
  width: 70%;
  height: 70%;
  background: radial-gradient(circle, rgba(0, 180, 255, 0.25) 0%, transparent 70%);
  filter: blur(100px);
  z-index: 0;
  animation: driftBlue 12s infinite alternate;
}

body::after {
  content: "";
  position: fixed;
  bottom: -18%;
  right: -8%;
  width: 80%;
  height: 80%;
  background: radial-gradient(circle, rgba(200, 100, 255, 0.3) 0%, transparent 70%);
  filter: blur(110px);
  z-index: 0;
  animation: driftPurple 14s infinite alternate;
}

@keyframes driftBlue {
  0% { transform: translate(0, 0) scale(1); }
  100% { transform: translate(5%, 8%) scale(1.1); }
}
@keyframes driftPurple {
  0% { transform: translate(0, 0) scale(1); }
  100% { transform: translate(-6%, -5%) scale(1.15); }
}

/* ========== 顶部导航菜单 ========== */
.navbar {
  position: relative;
  z-index: 10;
  width: 100%;
  max-width: 880px;
  margin-top: 1.5rem;
  margin-bottom: 2rem;
  background: rgba(12, 18, 32, 0.55);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 3rem;
  padding: 0.8rem 1.8rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: 0 15px 35px rgba(0, 0, 0, 0.5), inset 0 0 0 1px rgba(255, 255, 255, 0.06);
  flex-wrap: wrap;
  gap: 0.8rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  font-size: 1.3rem;
  color: #ffffff;
  text-decoration: none;
  letter-spacing: -0.3px;
}

.nav-logo i {
  color: #fbbf24;
  font-size: 1.6rem;
  filter: drop-shadow(0 0 10px #fbbf24aa);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.nav-link {
  color: #cbd5e1;
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  padding: 0.5rem 1.1rem;
  border-radius: 2.5rem;
  transition: all 0.25s ease;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  white-space: nowrap;
  background: transparent;
  border: 1px solid transparent;
}

.nav-link i {
  font-size: 0.9rem;
  color: #94a3b8;
  transition: color 0.25s;
}

.nav-link:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.2);
  color: #ffffff;
  transform: translateY(-1px);
}

.nav-link:hover i {
  color: #fbbf24;
}

.nav-link.active {
  background: rgba(37, 99, 235, 0.25);
  border-color: rgba(96, 165, 250, 0.5);
  color: #ffffff;
  font-weight: 600;
}

.nav-link.active i {
  color: #60a5fa;
}

.nav-cta {
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: white !important;
  border: 1px solid rgba(255,255,255,0.25) !important;
  font-weight: 600;
  box-shadow: 0 6px 18px rgba(37, 99, 235, 0.4);
}

.nav-cta:hover {
  background: linear-gradient(135deg, #3b82f6, #8b5cf6);
  box-shadow: 0 10px 25px rgba(124, 58, 237, 0.6);
}

.nav-cta i {
  color: #fbbf24 !important;
}

/* 移动端菜单按钮 */
.menu-toggle {
  display: none;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.2);
  color: white;
  font-size: 1.4rem;
  padding: 0.4rem 0.9rem;
  border-radius: 2rem;
  cursor: pointer;
  transition: 0.2s;
}

.menu-toggle:hover {
  background: rgba(255,255,255,0.15);
}

/* ========== 主容器 ========== */
.container {
  position: relative;
  z-index: 2;
  width: 100%;
  max-width: 880px;
  background: rgba(12, 18, 32, 0.65);
  backdrop-filter: blur(22px);
  -webkit-backdrop-filter: blur(22px);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 3.5rem;
  box-shadow: 0 35px 70px rgba(0, 0, 0, 0.8), inset 0 0 0 1px rgba(255, 255, 255, 0.08);
  padding: 2.5rem 2.3rem;
  color: #eef5ff;
}

.intro-section {
  margin-bottom: 2.8rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.12);
  padding-bottom: 2rem;
}

.intro-section h1 {
  font-size: 2.5rem;
  font-weight: 700;
  background: linear-gradient(to right, #9cdbff, #6d8cff, #c792ff);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1.2rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.intro-section h1 i {
  background: none;
  -webkit-text-fill-color: #fbbf24;
  font-size: 2.2rem;
  filter: drop-shadow(0 0 12px #fbbf24);
}

.intro-text {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  align-items: center;
}

.intro-desc {
  flex: 2;
  min-width: 250px;
  line-height: 1.7;
  color: #cbd5e1;
  font-size: 1.05rem;
  background: rgba(255,255,255,0.03);
  padding: 1.2rem 1.5rem;
  border-radius: 2rem;
}

.intro-desc strong {
  color: #ffffff;
  font-weight: 600;
}

.seo-badge {
  flex: 1;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  justify-content: flex-end;
}

.seo-tag {
  background: rgba(255,255,255,0.07);
  border: 1px solid rgba(255,255,255,0.22);
  padding: 0.4rem 1.2rem;
  border-radius: 3rem;
  font-size: 0.85rem;
  color: #b9c7ff;
  backdrop-filter: blur(5px);
}

.diagnosis-section h2 {
  font-size: 1.9rem;
  font-weight: 600;
  margin-bottom: 1.8rem;
  display: flex;
  align-items: center;
  gap: 0.7rem;
  color: #dfe7ff;
}

.options-grid {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
  margin-bottom: 2.5rem;
}

.option-item {
  background: rgba(18, 26, 45, 0.7);
  backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 2rem;
  padding: 1rem 1.8rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all 0.25s;
  cursor: pointer;
  box-shadow: 0 8px 18px rgba(0,0,0,0.4);
}

.option-item:hover {
  border-color: rgba(96, 165, 250, 0.65);
  background: rgba(28, 38, 65, 0.8);
  box-shadow: 0 0 28px rgba(59, 130, 246, 0.35);
  transform: translateY(-2px);
}

.option-left {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  flex: 1;
}

.option-left i {
  font-size: 1.6rem;
  color: #94a3b8;
  width: 2.2rem;
  text-align: center;
}

.option-left span {
  font-size: 1.1rem;
  font-weight: 500;
}

.severity-select {
  background: #1e293b;
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 2.5rem;
  padding: 0.5rem 1.2rem;
  color: white;
  font-weight: 500;
  cursor: pointer;
  outline: none;
  backdrop-filter: blur(10px);
  width: 180px;
  min-width: 180px;
  text-align: left;
  appearance: auto;
}

.btn-diagnose {
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  border: none;
  padding: 1.1rem 2.5rem;
  border-radius: 3rem;
  font-weight: 700;
  font-size: 1.2rem;
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  margin: 0 auto;
  cursor: pointer;
  box-shadow: 0 12px 30px rgba(37, 99, 235, 0.5);
  transition: 0.3s;
  border: 1px solid rgba(255,255,255,0.2);
}

.btn-diagnose:hover {
  transform: scale(1.05);
  box-shadow: 0 20px 40px rgba(124, 58, 237, 0.7);
}

.modal-overlay {
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  background: rgba(0,0,0,0.75);
  backdrop-filter: blur(18px);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.modal-box {
  background: rgba(16, 22, 40, 0.9);
  backdrop-filter: blur(35px);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 3.5rem;
  padding: 2.5rem 2.2rem;
  max-width: 460px;
  width: 90%;
  text-align: center;
  box-shadow: 0 45px 80px rgba(0,0,0,0.9);
  animation: popIn 0.3s ease-out;
}

@keyframes popIn {
  0% { transform: scale(0.85); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}

.modal-icon { font-size: 4rem; margin-bottom: 0.8rem; }
.modal-title { font-size: 2rem; font-weight: 700; margin-bottom: 0.8rem; }
.modal-description { color: #ccd6f0; font-size: 1.1rem; margin-bottom: 1.8rem; }

.recommend-badge {
  background: linear-gradient(135deg, #fbbf24, #f59e0b);
  color: #0f172a;
  font-weight: 700;
  padding: 0.8rem 1.8rem;
  border-radius: 3rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.2rem;
  margin-top: 0.4rem;
  box-shadow: 0 10px 24px rgba(251,191,36,0.5);
}

.close-modal {
  margin-top: 2rem;
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.3);
  padding: 0.7rem 2rem;
  border-radius: 3rem;
  color: white;
  font-weight: 600;
  cursor: pointer;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .navbar {
    padding: 0.8rem 1.2rem;
  }

  .nav-links {
    display: none;
    width: 100%;
    flex-direction: column;
    gap: 0.3rem;
    padding-top: 0.8rem;
  }

  .nav-links.show {
    display: flex;
  }

  .nav-link {
    width: 100%;
    justify-content: center;
    padding: 0.7rem;
  }

  .menu-toggle {
    display: block;
  }
}

@media (max-width: 600px) {
  .option-item {
    flex-wrap: wrap;
    gap: 0.8rem;
  }
  .severity-select {
    width: 100%;
    min-width: auto;
  }
}