/* ===== CSS Variables ===== */
:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-secondary: #0f172a;
  --color-accent: #06b6d4;
  --color-text: #334155;
  --color-text-light: #64748b;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-border: #e2e8f0;
  --color-card: #ffffff;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --container-max: 1200px;
}

/* ===== Reset & Base ===== */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

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

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

ul {
  list-style: none;
}

button {
  border: none;
  background: none;
  cursor: pointer;
  font-family: inherit;
}

/* ===== Layout ===== */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
}

.section__header {
  text-align: center;
  margin-bottom: 60px;
}

.section__tag {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 6px 16px;
  border-radius: 100px;
  margin-bottom: 16px;
}

.section__title {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--color-secondary);
  margin-bottom: 12px;
  line-height: 1.2;
}

.section__desc {
  font-size: 1.1rem;
  color: var(--color-text-light);
  max-width: 560px;
  margin: 0 auto;
}

/* ===== Header ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: var(--transition);
}

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

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.nav__logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-secondary);
}

.nav__list {
  display: flex;
  gap: 8px;
}

.nav__link {
  display: block;
  padding: 8px 16px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-light);
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.nav__link:hover,
.nav__link.active {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 28px;
}

.nav__toggle span {
  display: block;
  height: 2px;
  background: var(--color-secondary);
  border-radius: 2px;
  transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, var(--color-bg) 0%, var(--color-primary-light) 100%);
}

.hero__container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 60px;
  padding-top: 72px;
}

.hero__title {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.15;
  color: var(--color-secondary);
  margin-bottom: 20px;
}

.hero__subtitle {
  font-size: 1.15rem;
  color: var(--color-text-light);
  margin-bottom: 36px;
  max-width: 480px;
  line-height: 1.7;
}

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

.hero__visual {
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero__shape {
  width: 400px;
  height: 400px;
  border-radius: 30% 70% 70% 30% / 30% 30% 70% 70%;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  opacity: 0.15;
  animation: morph 8s ease-in-out infinite;
}

@keyframes morph {
  0%, 100% { border-radius: 30% 70% 70% 30% / 30% 30% 70% 70%; }
  25% { border-radius: 58% 42% 75% 25% / 76% 46% 54% 24%; }
  50% { border-radius: 50% 50% 33% 67% / 55% 27% 73% 45%; }
  75% { border-radius: 33% 67% 58% 42% / 63% 68% 32% 37%; }
}

.hero__scroll {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--color-text-light);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
}

.hero__scroll-line {
  width: 1px;
  height: 40px;
  background: var(--color-text-light);
  animation: scrollDown 2s ease-in-out infinite;
}

@keyframes scrollDown {
  0% { transform: scaleY(0); transform-origin: top; }
  50% { transform: scaleY(1); transform-origin: top; }
  51% { transform: scaleY(1); transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; }
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: var(--transition);
  cursor: pointer;
}

.btn--primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}

.btn--primary:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
  transform: translateY(-1px);
}

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

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

.btn--full {
  width: 100%;
}

/* ===== About ===== */
.about {
  background: var(--color-bg-alt);
}

.about__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-bottom: 60px;
}

.about__card {
  background: var(--color-card);
  padding: 32px 24px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  transition: var(--transition);
  text-align: center;
}

.about__card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary-light);
}

.about__icon {
  width: 56px;
  height: 56px;
  margin: 0 auto 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary-light);
  border-radius: var(--radius-md);
  color: var(--color-primary);
}

.about__icon svg {
  width: 28px;
  height: 28px;
}

.about__card-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-secondary);
  margin-bottom: 8px;
}

.about__card-desc {
  font-size: 0.9rem;
  color: var(--color-text-light);
  line-height: 1.6;
}

/* ===== Stats ===== */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  padding: 48px;
  background: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
}

.stats__item {
  text-align: center;
}

.stats__number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--color-primary);
  line-height: 1;
}

.stats__suffix {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
}

.stats__label {
  display: block;
  margin-top: 8px;
  font-size: 0.9rem;
  color: var(--color-text-light);
}

/* ===== Projects ===== */
.projects__filter {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.projects__filter-btn {
  padding: 8px 20px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-light);
  border: 1px solid var(--color-border);
  border-radius: 100px;
  transition: var(--transition);
}

.projects__filter-btn:hover,
.projects__filter-btn.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

.projects__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.project-card {
  background: var(--color-card);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  transition: var(--transition);
}

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

.project-card__image {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  background: var(--color-bg-alt);
}

.project-card__placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, #f0f9ff 100%);
}

.project-card__placeholder svg {
  width: 48px;
  height: 48px;
  color: var(--color-primary);
  opacity: 0.4;
}

.project-card__overlay {
  position: absolute;
  inset: 0;
  background: rgba(15, 23, 42, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: var(--transition);
}

.project-card:hover .project-card__overlay {
  opacity: 1;
}

.project-card__view {
  padding: 10px 24px;
  background: #fff;
  color: var(--color-secondary);
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  transform: translateY(10px);
  transition: var(--transition);
}

.project-card:hover .project-card__view {
  transform: translateY(0);
}

.project-card__body {
  padding: 24px;
}

.project-card__tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 4px 10px;
  border-radius: 100px;
  margin-bottom: 12px;
}

.project-card__title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-secondary);
  margin-bottom: 8px;
}

.project-card__desc {
  font-size: 0.875rem;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 16px;
}

.project-card__tech {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.project-card__tech span {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-light);
  background: var(--color-bg-alt);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
}

/* ===== Team ===== */
.team {
  background: var(--color-bg-alt);
}

.team__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 28px;
}

.team__card {
  background: var(--color-card);
  padding: 40px 24px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  text-align: center;
  transition: var(--transition);
}

.team__card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.team__avatar {
  width: 80px;
  height: 80px;
  margin: 0 auto 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary-light);
  border-radius: 50%;
  color: var(--color-primary);
}

.team__avatar svg {
  width: 40px;
  height: 40px;
}

.team__name {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-secondary);
  margin-bottom: 4px;
}

.team__role {
  display: block;
  font-size: 0.85rem;
  color: var(--color-primary);
  font-weight: 500;
  margin-bottom: 12px;
}

.team__desc {
  font-size: 0.85rem;
  color: var(--color-text-light);
  line-height: 1.6;
}

/* ===== Contact ===== */
.contact__wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: start;
}

.contact__text {
  font-size: 1rem;
  color: var(--color-text-light);
  line-height: 1.7;
  margin-bottom: 32px;
}

.contact__details {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.contact__detail {
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.contact__detail svg {
  width: 24px;
  height: 24px;
  color: var(--color-primary);
  flex-shrink: 0;
  margin-top: 2px;
}

.contact__detail strong {
  display: block;
  font-size: 0.9rem;
  color: var(--color-secondary);
  margin-bottom: 2px;
}

.contact__detail span {
  font-size: 0.9rem;
  color: var(--color-text-light);
}

/* ===== Form ===== */
.contact__form {
  background: var(--color-card);
  padding: 40px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
}

.form__group {
  position: relative;
  margin-bottom: 24px;
}

.form__input {
  width: 100%;
  padding: 14px 16px;
  font-size: 0.9rem;
  font-family: inherit;
  color: var(--color-text);
  background: var(--color-bg-alt);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: var(--transition);
  outline: none;
}

.form__input:focus {
  border-color: var(--color-primary);
  background: var(--color-bg);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

textarea.form__input {
  resize: vertical;
  min-height: 100px;
}

.form__label {
  position: absolute;
  top: 14px;
  left: 16px;
  font-size: 0.9rem;
  color: var(--color-text-light);
  pointer-events: none;
  transition: var(--transition);
}

.form__input:focus ~ .form__label,
.form__input:not(:placeholder-shown) ~ .form__label {
  top: -10px;
  left: 12px;
  font-size: 0.75rem;
  color: var(--color-primary);
  background: var(--color-bg);
  padding: 0 6px;
}

/* ===== Footer ===== */
.footer {
  background: var(--color-secondary);
  color: #94a3b8;
  padding: 60px 0 0;
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer__logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: #fff;
  display: block;
  margin-bottom: 12px;
}

.footer__desc {
  font-size: 0.9rem;
  line-height: 1.7;
  max-width: 280px;
}

.footer__heading {
  color: #fff;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.footer__links ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer__links a {
  font-size: 0.875rem;
  transition: var(--transition);
}

.footer__links a:hover {
  color: #fff;
}

.footer__bottom {
  padding: 20px 0;
  text-align: center;
  font-size: 0.8rem;
}

/* ===== Scroll Top ===== */
.scroll-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: var(--transition);
  z-index: 99;
}

.scroll-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.scroll-top:hover {
  background: var(--color-primary-dark);
}

.scroll-top svg {
  width: 20px;
  height: 20px;
}

/* ===== Animations ===== */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Project Detail ===== */
.project-detail__back {
  margin-bottom: 32px;
}

.project-detail__back a {
  font-size: 0.9rem;
  color: var(--color-primary);
  font-weight: 500;
  transition: var(--transition);
}

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

.project-detail__header {
  margin-bottom: 32px;
}

.project-detail__title {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--color-secondary);
  margin: 12px 0;
  line-height: 1.2;
}

.project-detail__desc {
  font-size: 1.1rem;
  color: var(--color-text-light);
  line-height: 1.7;
}

.project-detail__meta {
  display: flex;
  gap: 40px;
  padding: 24px 0;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 32px;
}

.project-detail__meta-item strong {
  display: block;
  font-size: 0.8rem;
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}

.project-detail__meta-item span {
  font-size: 0.95rem;
  color: var(--color-secondary);
  font-weight: 500;
}

.project-detail__tech {
  margin-bottom: 40px;
}

.project-detail__tech h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-secondary);
  margin-bottom: 12px;
}

.project-detail__content {
  max-width: 720px;
}

/* ===== Markdown Body ===== */
.markdown-body h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-secondary);
  margin: 40px 0 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
}

.markdown-body h3 {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-secondary);
  margin: 32px 0 12px;
}

.markdown-body p {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--color-text);
  margin-bottom: 16px;
}

.markdown-body ul,
.markdown-body ol {
  padding-left: 24px;
  margin-bottom: 16px;
}

.markdown-body li {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--color-text);
  margin-bottom: 8px;
}

.markdown-body strong {
  color: var(--color-secondary);
  font-weight: 600;
}

.markdown-body code {
  font-size: 0.875rem;
  background: var(--color-bg-alt);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  font-family: 'Fira Code', 'Consolas', monospace;
}

.markdown-body pre {
  background: var(--color-secondary);
  color: #e2e8f0;
  padding: 20px;
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin-bottom: 16px;
}

.markdown-body pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
}

.markdown-body blockquote {
  border-left: 3px solid var(--color-primary);
  padding: 12px 20px;
  margin: 16px 0;
  background: var(--color-primary-light);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text);
}

.markdown-body img {
  max-width: 100%;
  border-radius: var(--radius-md);
  margin: 16px 0;
}

.markdown-body a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.markdown-body a:hover {
  color: var(--color-primary-dark);
}

.markdown-body hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 32px 0;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .hero__title {
    font-size: 2.75rem;
  }

  .about__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .stats {
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
  }

  .projects__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .team__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer__grid {
    grid-template-columns: 1fr 1fr;
  }
}

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

  .section__title {
    font-size: 1.75rem;
  }

  .nav__toggle {
    display: flex;
  }

  .nav__menu {
    position: fixed;
    top: 72px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 24px;
    transform: translateY(-120%);
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
  }

  .nav__menu.open {
    transform: translateY(0);
  }

  .nav__list {
    flex-direction: column;
    gap: 4px;
  }

  .hero__container {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero__title {
    font-size: 2.25rem;
  }

  .hero__subtitle {
    margin: 0 auto 36px;
  }

  .hero__actions {
    justify-content: center;
  }

  .hero__visual {
    display: none;
  }

  .about__grid {
    grid-template-columns: 1fr;
  }

  .stats {
    grid-template-columns: repeat(2, 1fr);
    padding: 32px;
  }

  .projects__grid {
    grid-template-columns: 1fr;
  }

  .team__grid {
    grid-template-columns: 1fr;
  }

  .contact__wrapper {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .contact__form {
    padding: 24px;
  }

  .footer__grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }
}