:root {
  --color-bg: #ffffff;
  --color-surface: #f7f8fa;
  --color-text: #1f2933;
  --color-text-light: #6b7280;
  --color-primary: #5b7cfa;
  --color-primary-dark: #3f5fe0;
  --color-border: #e5e7eb;
  --shadow-sm: 0 1px 3px rgba(17, 24, 39, 0.08);
  --shadow-md: 0 4px 16px rgba(17, 24, 39, 0.1);
  --radius: 12px;
  --container: 1080px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 72px;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
  display: block;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Header / Nav ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s, box-shadow 0.3s;
}

.site-header.scrolled {
  border-bottom-color: var(--color-border);
  box-shadow: var(--shadow-sm);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-brand {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: 0.5px;
}

.nav-links {
  display: flex;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--color-text-light);
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--color-primary);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.25s, opacity 0.25s;
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---------- Hero ---------- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: linear-gradient(160deg, #f6f8ff 0%, #ffffff 45%, #f3f6ff 100%);
  padding: 120px 0 80px;
}

.hero-inner {
  text-align: center;
}

.hero-avatar {
  width: 104px;
  height: 104px;
  margin: 0 auto 28px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), #a78bfa);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 8px 24px rgba(91, 124, 250, 0.35);
  animation: float 5s ease-in-out infinite;
}

.hero-avatar-inner {
  width: 92px;
  height: 92px;
  border-radius: 50%;
  background: var(--color-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.hero-greeting {
  font-size: 1.05rem;
  color: var(--color-text-light);
}

.hero-name {
  font-size: clamp(2.6rem, 6vw, 4rem);
  font-weight: 800;
  letter-spacing: 1px;
  margin: 8px 0 12px;
  background: linear-gradient(120deg, var(--color-primary), #a78bfa);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-role {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-text);
}

.hero-desc {
  max-width: 560px;
  margin: 16px auto 32px;
  color: var(--color-text-light);
  font-size: 1.02rem;
}

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 0.98rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: transform 0.2s, box-shadow 0.2s, background 0.2s;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 4px 14px rgba(91, 124, 250, 0.35);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 6px 18px rgba(91, 124, 250, 0.45);
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 1.5px solid var(--color-border);
}

.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.hero-socials {
  display: flex;
  gap: 28px;
  justify-content: center;
  margin-top: 40px;
}

.hero-socials a {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text-light);
  transition: color 0.2s;
}

.hero-socials a:hover {
  color: var(--color-primary);
}

/* ---------- Section ---------- */
.section {
  padding: 96px 0;
}

.section-title {
  text-align: center;
  font-size: clamp(1.8rem, 3.5vw, 2.4rem);
  font-weight: 700;
}

.section-subtitle {
  text-align: center;
  color: var(--color-primary);
  font-weight: 600;
  letter-spacing: 3px;
  text-transform: uppercase;
  font-size: 0.82rem;
  margin: 6px 0 56px;
}

.about-content {
  max-width: 720px;
  margin: 0 auto;
  color: var(--color-text-light);
  font-size: 1.02rem;
}

.about-content p + p {
  margin-top: 16px;
}

.about-stats {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
  text-align: center;
}

.about-stats strong {
  display: block;
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-primary);
}

.about-stats span {
  color: var(--color-text-light);
  font-size: 0.92rem;
}

/* ---------- Skills ---------- */
.skills {
  background: var(--color-surface);
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 24px;
}

.skill-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px 24px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.25s, box-shadow 0.25s;
}

.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.skill-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: rgba(91, 124, 250, 0.12);
  color: var(--color-primary);
  font-size: 1.3rem;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}

.skill-card h3 {
  font-size: 1.05rem;
  margin-bottom: 14px;
}

.skill-bar {
  height: 8px;
  border-radius: 99px;
  background: var(--color-border);
  overflow: hidden;
  margin-bottom: 10px;
}

.skill-bar-fill {
  display: block;
  height: 100%;
  width: 0;
  border-radius: 99px;
  background: linear-gradient(90deg, var(--color-primary), #a78bfa);
  transition: width 1.2s cubic-bezier(0.22, 1, 0.36, 1);
}

.skill-level {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-top: 40px;
}

.tag {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 6px 16px;
  font-size: 0.88rem;
  color: var(--color-text-light);
  transition: color 0.2s, border-color 0.2s;
}

.tag:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
}

/* ---------- Projects ---------- */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform 0.25s, box-shadow 0.25s;
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.project-cover {
  height: 160px;
  background: linear-gradient(135deg, var(--c), color-mix(in srgb, var(--c) 60%, #fff));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  font-weight: 800;
  color: rgba(255, 255, 255, 0.9);
}

.project-body {
  padding: 24px;
}

.project-body h3 {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

.project-body p {
  color: var(--color-text-light);
  font-size: 0.94rem;
  margin-bottom: 14px;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
}

.project-tags span {
  font-size: 0.78rem;
  color: var(--color-primary);
  background: rgba(91, 124, 250, 0.1);
  padding: 4px 10px;
  border-radius: 6px;
}

.project-link {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--color-primary);
}

.project-link:hover {
  color: var(--color-primary-dark);
}

/* ---------- Contact ---------- */
.contact {
  background: var(--color-surface);
}

.contact-content {
  max-width: 640px;
  margin: 0 auto;
  text-align: center;
}

.contact-desc {
  color: var(--color-text-light);
  margin-bottom: 24px;
}

.contact-channels {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 40px;
}

.channel {
  font-size: 1rem;
  color: var(--color-text);
  transition: color 0.2s;
}

.channel:hover {
  color: var(--color-primary);
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 14px;
  text-align: left;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--color-border);
  border-radius: 10px;
  font-size: 0.95rem;
  font-family: inherit;
  background: var(--color-bg);
  color: var(--color-text);
  transition: border-color 0.2s, box-shadow 0.2s;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(91, 124, 250, 0.15);
}

.contact-form button {
  align-self: flex-start;
}

.form-success {
  margin-top: 20px;
  color: #15803d;
  font-weight: 600;
}

/* ---------- Footer ---------- */
.site-footer {
  background: var(--color-text);
  color: #cbd5e1;
  padding: 28px 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.9rem;
}

.site-footer a:hover {
  color: #fff;
}

/* ---------- Scroll reveal ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .section {
    padding: 72px 0;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  .nav-links.open {
    max-height: 260px;
  }

  .nav-links li {
    text-align: center;
  }

  .nav-links a {
    display: block;
    padding: 14px 0;
  }

  .about-stats {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .form-row {
    grid-template-columns: 1fr;
  }
}