:root {
    --primary: #2c7be5;
    --primary-dark: #1a68d1;
    --secondary: #12263f;
    --bg: #f8fbff;
    --card-bg: #fff;
    --footer-bg: #19223a;
    --gray: #6c757d;
    --border-radius: 18px;
    --shadow: 0 4px 24px rgba(44,123,229,0.08);
    --shadow-card: 0 2px 12px rgba(44,123,229,0.10);
    --transition: all 0.3s cubic-bezier(.4,0,.2,1);
    --font-main: 'Source Sans Pro', 'PingFang SC', 'Microsoft YaHei', Arial, sans-serif;
  }
  
  html, body {
    margin: 0;
    padding: 0;
    background: var(--bg);
    font-family: var(--font-main);
    color: var(--secondary);
  }
  
  .container {
    width: 1200px;
    max-width: 96vw;
    margin: 0 auto;
  }
  
  .navbar {
    background: #fff;
    box-shadow: 0 2px 8px rgba(44,123,229,0.04);
    position: sticky;
    top: 0;
    z-index: 10;
  }
  
  .nav-flex {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
  }
  
  .logo {
    display: flex;
    align-items: center;
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--primary);
  }
  .logo-icon {
    font-size: 2rem;
    margin-right: 8px;
  }
  .logo-text {
    letter-spacing: 2px;
  }
  
  .nav-list {
    display: flex;
    gap: 36px;
    list-style: none;
    margin: 0;
    padding: 0;
  }
  .nav-list li a {
    color: var(--secondary);
    text-decoration: none;
    font-size: 1.1rem;
    font-weight: 500;
    transition: color .2s;
  }
  .nav-list li.active a,
  .nav-list li a:hover {
    color: var(--primary);
  }
  
  .banner {
    background: linear-gradient(120deg, #eaf3ff 0%, #f8fbff 100%);
    padding: 60px 0 40px 0;
  }
  .banner-flex {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 40px;
  }
  .banner-left {
    flex: 1.2;
  }
  .banner-tag {
    display: inline-block;
    background: #eaf3ff;
    color: var(--primary);
    border-radius: 999px;
    padding: 6px 18px;
    font-size: 1rem;
    margin-bottom: 24px;
    font-weight: 600;
  }
  .banner-left h1 {
    font-size: 2.8rem;
    font-weight: 900;
    margin: 0 0 18px 0;
    line-height: 1.2;
    color: var(--secondary);
  }
  .banner-left .highlight {
    color: var(--primary);
  }
  .banner-desc {
    font-size: 1.18rem;
    color: var(--gray);
    margin-bottom: 32px;
  }
  .banner-btns {
    display: flex;
    gap: 18px;
  }
  .btn {
    font-size: 1.1rem;
    padding: 12px 32px;
    border-radius: 999px;
    border: none;
    cursor: pointer;
    font-weight: 700;
    transition: var(--transition);
  }
  .btn-primary {
    background: var(--primary);
    color: #fff;
    box-shadow: var(--shadow);
  }
  .btn-primary:hover {
    background: var(--primary-dark);
  }
  .btn-outline {
    background: #fff;
    color: var(--primary);
    border: 2px solid var(--primary);
  }
  .btn-outline:hover {
    background: var(--primary);
    color: #fff;
  }
  
  .banner-right {
    flex: 1;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .banner-img-wrap {
    position: relative;
    width: 340px;
    height: 260px;
  }
  .banner-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-card);
  }
  .banner-card {
    position: absolute;
    background: #fff;
    box-shadow: var(--shadow-card);
    border-radius: 14px;
    padding: 18px 28px 10px 28px;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--primary);
    text-align: center;
    min-width: 90px;
  }
  .banner-card.user {
    top: 18px;
    right: -38px;
  }
  .banner-card.acc {
    left: -38px;
    bottom: 18px;
  }
  .banner-card span {
    display: block;
    font-size: 1rem;
    color: var(--gray);
    font-weight: 400;
    margin-top: 2px;
  }
  
  .features {
    padding: 70px 0 40px 0;
    background: #fff;
  }
  .section-title {
    font-size: 2rem;
    font-weight: 800;
    text-align: center;
    margin-bottom: 10px;
    color: var(--secondary);
  }
  .section-desc {
    text-align: center;
    color: var(--gray);
    font-size: 1.1rem;
    margin-bottom: 38px;
  }
  .features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
  }
  .feature-card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-card);
    padding: 38px 24px 30px 24px;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
  }
  .feature-card:hover {
    transform: translateY(-6px) scale(1.03);
    box-shadow: 0 8px 32px rgba(44,123,229,0.13);
  }
  .feature-icon {
    font-size: 2.2rem;
    margin-bottom: 18px;
  }
  .feature-title {
    font-size: 1.18rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--primary);
  }
  .feature-desc {
    color: var(--gray);
    font-size: 1rem;
    line-height: 1.7;
  }
  
  .about {
    background: var(--bg);
    padding: 70px 0 40px 0;
  }
  .about-flex {
    display: flex;
    align-items: center;
    gap: 60px;
  }
  .about-img-wrap {
    flex: 1;
    min-width: 320px;
  }
  .about-img {
    width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-card);
  }
  .about-content {
    flex: 2;
  }
  .about-content .section-title {
    text-align: left;
  }
  .about-desc {
    color: var(--gray);
    font-size: 1.1rem;
    margin-bottom: 18px;
  }
  .about-stats {
    display: flex;
    gap: 32px;
    margin: 28px 0 18px 0;
  }
  .stat-card {
    background: #fff;
    border-radius: 12px;
    box-shadow: var(--shadow-card);
    padding: 18px 28px;
    text-align: center;
    min-width: 90px;
  }
  .stat-num {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary);
  }
  .stat-label {
    font-size: 1rem;
    color: var(--gray);
    margin-top: 2px;
  }
  
  .footer {
    background: var(--footer-bg);
    color: #fff;
    padding: 60px 0 30px 0;
  }
  .footer-flex {
    display: flex;
    gap: 60px;
    justify-content: space-between;
    flex-wrap: wrap;
  }
  .footer-col {
    flex: 1;
    min-width: 200px;
    margin-bottom: 30px;
  }
  .footer-logo {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 18px;
    color: #fff;
  }
  .footer-desc {
    color: #bfc8e2;
    font-size: 1rem;
    margin-bottom: 18px;
  }
  .footer-title {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: #fff;
  }
  .footer-links,
  .footer-contact {
    list-style: none;
    padding: 0;
    margin: 0;
  }
  .footer-links li,
  .footer-contact li {
    margin-bottom: 10px;
    color: #bfc8e2;
    font-size: 1rem;
  }
  .footer-links li a {
    color: #bfc8e2;
    text-decoration: none;
    transition: color .2s;
  }
  .footer-links li a:hover {
    color: #fff;
  }
  .footer-socials {
    margin-top: 18px;
  }
  .footer-social {
    display: inline-block;
    width: 28px;
    height: 28px;
    background: #253053;
    border-radius: 50%;
    margin-right: 8px;
  }
  
  @media (max-width: 1100px) {
    .container { width: 98vw; }
    .banner-flex, .about-flex, .footer-flex { flex-direction: column; gap: 32px; }
    .features-grid { grid-template-columns: 1fr 1fr; }
    .about-img-wrap, .about-content { width: 100%; }
  }
  @media (max-width: 700px) {
    .container { width: 100vw; padding: 0 8px; }
    .banner { padding: 30px 0 20px 0; }
    .features { padding: 30px 0 20px 0; }
    .about { padding: 30px 0 20px 0; }
    .footer { padding: 30px 0 10px 0; }
    .features-grid { grid-template-columns: 1fr; }
    .about-stats { flex-direction: column; gap: 12px; }
    .footer-flex { gap: 20px; }
  }
  
  /* 弹窗样式 */
  #overlay {
    display: none;
    position: fixed;
    top: 0; left: 0; width: 100vw; height: 100vh;
    background: rgba(0,0,0,0.55);
    z-index: 1000;
  }
  #diabetes-modal, #result-modal {
    display: none;
    position: fixed;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    background: #fff;
    border-radius: 18px;
    box-shadow: 0 8px 32px rgba(44,123,229,0.18);
    z-index: 1001;
    width: 95vw;
    max-width: 800px;
    max-height: 85vh;
    overflow-y: auto;
    padding: 28px 24px 24px 24px;
    font-size: 1.1rem;
  }
  #diabetes-modal h2, #result-modal h2 {
    text-align: center;
    color: var(--primary);
    font-size: 1.8rem;
    margin-bottom: 24px;
  }
  #diabetes-modal {
    max-width: 800px;
    padding: 40px 40px 36px 40px;
  }
  #diabetesForm {
    display: flex;
    flex-direction: column;
    gap: 28px;
  }
  .form-section {
    background: #f8fbff;
    border-radius: 12px;
    padding: 22px 18px 10px 18px;
    margin-bottom: 8px;
    box-shadow: 0 2px 8px rgba(44,123,229,0.06);
  }
  .form-section-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 14px;
  }
  .form-row {
    display: flex;
    gap: 24px;
    margin-bottom: 18px;
  }
  .form-row label {
    min-width: 100px;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--secondary);
    margin-right: 6px;
    align-self: center;
  }
  .form-row input, .form-row select {
    flex: 1;
    padding: 14px 16px;
    font-size: 1.1rem;
    border-radius: 8px;
    border: 1.5px solid #e3eaf2;
    margin-right: 0;
  }
  .form-row button,
  #diabetesForm button[type=button] {
    padding: 14px 0;
    font-size: 1.1rem;
    min-width: 120px;
    margin: 0 6px;
  }
  .section-note {
    color: var(--gray);
    font-size: 0.98rem;
    margin-bottom: 6px;
  }
  .close-button {
    position: absolute;
    top: 18px; right: 22px;
    font-size: 1.6rem;
    color: var(--gray);
    cursor: pointer;
    transition: color .2s;
  }
  .close-button:hover { color: var(--primary); }
  .result-container {
    margin-top: 18px;
    text-align: center;
  }
  .probability-circle {
    margin: 0 auto 18px auto;
    position: relative;
    width: 140px; height: 140px;
  }
  .probability-circle svg {
    width: 140px; height: 140px;
    transform: rotate(-90deg);
  }
  .probability-circle .circle-bg {
    fill: none;
    stroke: #e3eaf2;
    stroke-width: 12;
  }
  .probability-circle .circle-fill {
    fill: none;
    stroke: url(#gradient);
    stroke-width: 12;
    stroke-linecap: round;
    stroke-dasharray: 440;
    stroke-dashoffset: 440;
    transition: stroke-dashoffset 1s cubic-bezier(.4,0,.2,1);
  }
  .probability-circle .circle-text {
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary);
  }
  .probability-circle .circle-label {
    position: absolute;
    bottom: -28px; left: 50%;
    transform: translateX(-50%);
    font-size: 1rem;
    color: var(--gray);
  }
  .info-cards {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-top: 18px;
    flex-wrap: wrap;
  }
  .info-card {
    background: #f8fbff;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(44,123,229,0.06);
    padding: 18px 22px;
    min-width: 120px;
    text-align: center;
  }
  .info-card .icon {
    font-size: 1.4rem;
    margin-bottom: 6px;
  }
  .info-card h4 {
    font-size: 1.1rem;
    color: var(--primary);
    margin: 8px 0 4px 0;
  }
  .info-card p {
    color: var(--secondary);
    font-size: 1rem;
    margin: 0;
  }
  .error-message {
    color: var(--primary);
    font-size: 1.1rem;
    margin-top: 18px;
  }
  @media (max-width: 600px) {
    .banner-img-wrap, .about-img-wrap { width: 100%; height: auto; }
    .banner-img, .about-img { width: 100%; height: auto; }
    #diabetes-modal, #result-modal { padding: 16px 4vw; }
  }
  .step-progress {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 24px;
    gap: 12px;
  }
  .progress-step {
    font-size: 0.95rem;
    color: var(--gray);
    padding: 6px 12px;
    border-radius: 999px;
    background: #f8fbff;
    transition: var(--transition);
  }
  .progress-step.active {
    background: var(--primary);
    color: #fff;
    box-shadow: 0 2px 8px rgba(44,123,229,0.13);
  }
  .progress-line {
    width: 48px;
    height: 4px;
    background: #eaf3ff;
    margin: 0 0px;
    border-radius: 2px;
    z-index: 0;
  }
  .progress-line.active {
    background: var(--primary);
  }
  @media (max-width: 700px) {
    #diabetes-modal { 
      padding: 24px 20px 20px 20px;
      width: 92vw;
    }
    .form-row { 
      flex-direction: column; 
      gap: 6px;
      margin-bottom: 14px;
    }
    .form-row label {
      min-width: auto;
      margin-bottom: 4px;
    }
    .form-row input, .form-row select {
      padding: 12px 14px;
    }
  }