/* ============================================
   MUYU WANG - Personal Professional Site
   Design System & Styles
   ============================================ */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ===== Design Tokens ===== */
:root {
  /* Colors - Warm Neutral Palette */
  --color-bg: #F7F5F2;
  --color-bg-warm: #ECE9E3;
  --color-bg-warm-deep: #E4E0D8;
  --color-text: #2C2C2C;
  --color-text-muted: #6B6B6B;
  --color-text-light: #8A8A8A;
  --color-border: rgba(0, 0, 0, 0.05);
  --color-border-medium: rgba(0, 0, 0, 0.08);
  --color-link: #2C2C2C;
  --color-link-hover: #555555;

  /* Typography - Font Families */
  --font-heading: 'Cormorant Garamond', 'Noto Serif TC', Georgia, serif;
  --font-body: 'Karla', 'Noto Sans TC', system-ui, sans-serif;

  /* Typography - Sizes (with fluid scaling) */
  --text-h1: clamp(2.5rem, 5vw, 3.25rem);       /* 40-52px */
  --text-h2: clamp(1.75rem, 3.5vw, 2.25rem);    /* 28-36px */
  --text-h3: clamp(1.25rem, 2.5vw, 1.5rem);     /* 20-24px */
  --text-lead: clamp(1.0625rem, 2vw, 1.25rem);  /* 17-20px */
  --text-body: clamp(0.9375rem, 1.5vw, 1.0625rem); /* 15-17px */
  --text-micro: 0.8125rem;                       /* 13px */

  /* Typography - Line Heights */
  --leading-tight: 1.2;
  --leading-snug: 1.4;
  --leading-relaxed: 1.7;
  --leading-loose: 1.9;

  /* Layout */
  --max-width-prose: 65ch;
  --max-width-page: 1100px;
  --max-width-wide: 1300px;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-2xl: 6rem;
  --space-section: clamp(4rem, 10vw, 7rem);

  /* Header */
  --header-height: 80px;
}

/* ===== Body & Page ===== */
body {
  font-family: var(--font-body);
  font-size: var(--text-body);
  line-height: var(--leading-relaxed);
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ===== Typography ===== */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 400;
  line-height: var(--leading-tight);
  color: var(--color-text);
}

h1 {
  font-size: var(--text-h1);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--text-h2);
  letter-spacing: -0.01em;
}

h3 {
  font-size: var(--text-h3);
}

.lead {
  font-size: var(--text-lead);
  line-height: var(--leading-loose);
  color: var(--color-text-muted);
}

.micro {
  font-size: var(--text-micro);
  color: var(--color-text-light);
}

p {
  max-width: var(--max-width-prose);
}

p + p {
  margin-top: var(--space-md);
}

a {
  color: var(--color-link);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

a:hover {
  color: var(--color-link-hover);
  text-decoration-color: var(--color-text-light);
}

/* ===== Layout Containers ===== */
.container {
  width: 100%;
  max-width: var(--max-width-page);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container--wide {
  max-width: var(--max-width-wide);
}

.container--narrow {
  max-width: 800px;
}

/* ===== Header ===== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.header__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.header__brand {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 500;
  text-decoration: none;
  color: var(--color-text);
  letter-spacing: 0.01em;
}

.header__brand:hover {
  text-decoration: none;
}

.header__right {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

/* Navigation */
.nav {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.nav__link {
  font-size: var(--text-micro);
  text-decoration: none;
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
  padding: var(--space-xs) 0;
  position: relative;
  transition: color 0.2s ease;
}

.nav__link:hover,
.nav__link.active {
  color: var(--color-text);
  text-decoration: none;
}

.nav__link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 1px;
  background-color: var(--color-text);
}

/* Language Switcher */
.lang-switch {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-micro);
  color: var(--color-text-muted);
}

.lang-switch__link {
  text-decoration: none;
  color: var(--color-text-light);
  padding: 2px 6px;
  border-radius: 3px;
  transition: color 0.2s ease, background-color 0.2s ease;
}

.lang-switch__link:hover {
  color: var(--color-text);
  text-decoration: none;
}

.lang-switch__link.active {
  color: var(--color-text);
  background-color: var(--color-bg-warm);
}

.lang-switch__divider {
  color: var(--color-border-medium);
}

/* Mobile Menu Toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-xs);
  color: var(--color-text);
}

.nav-toggle__icon {
  display: block;
  width: 20px;
  height: 2px;
  background-color: currentColor;
  position: relative;
}

.nav-toggle__icon::before,
.nav-toggle__icon::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: currentColor;
}

.nav-toggle__icon::before {
  top: -6px;
}

.nav-toggle__icon::after {
  top: 6px;
}

/* ===== Main Content ===== */
.main {
  flex: 1;
}

.page-content {
  padding-top: var(--space-section);
  padding-bottom: var(--space-section);
}

.page-content > h1 + * {
  margin-top: var(--space-lg);
}

/* ===== Hero Section ===== */
.hero {
  padding: var(--space-section) 0;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: var(--space-2xl);
  align-items: center;
}

.hero__content {
  max-width: var(--max-width-prose);
}

.hero__title {
  margin-bottom: var(--space-md);
}

.hero__lead {
  font-size: var(--text-lead);
  line-height: var(--leading-loose);
  color: var(--color-text-muted);
  max-width: 55ch;
}

.hero__cta {
  margin-top: var(--space-lg);
}

/* Hero Portrait */
.hero__portrait {
  display: flex;
  justify-content: flex-end;
  align-items: center;
}

.hero__portrait-wrapper {
  position: relative;
  width: 100%;
  max-width: 400px;
  aspect-ratio: 4 / 5;
  overflow: hidden;
  border-radius: 8px;
}

.hero__portrait-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
  filter: grayscale(15%) contrast(0.95);
  transition: filter 0.4s ease;
}

.hero__portrait-wrapper:hover .hero__portrait-img {
  filter: grayscale(0%) contrast(1);
}

/* Subtle frame effect */
.hero__portrait-wrapper::after {
  content: '';
  position: absolute;
  inset: 0;
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: 6px;
  pointer-events: none;
}

/* ===== Sections ===== */
.section {
  padding: var(--space-section) 0;
}

.section--warm {
  background-color: var(--color-bg-warm);
}

.section__header {
  margin-bottom: var(--space-lg);
}

.section__title {
  margin-bottom: var(--space-sm);
}

/* ===== Separator ===== */
.separator {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-xl) 0;
}

.separator--spaced {
  margin: var(--space-section) 0;
}

/* ===== Content Blocks ===== */
.content-block {
  margin-bottom: var(--space-xl);
}

.content-block:last-child {
  margin-bottom: 0;
}

.content-block__title {
  margin-bottom: var(--space-sm);
}

.content-block__text {
  color: var(--color-text-muted);
}

/* ===== Cards / List Items ===== */
.card-list {
  display: grid;
  gap: var(--space-lg);
}

.card {
  padding: var(--space-lg);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  transition: border-color 0.2s ease;
}

.card:hover {
  border-color: var(--color-border-medium);
}

.card__title {
  margin-bottom: var(--space-xs);
}

.card__meta {
  font-size: var(--text-micro);
  color: var(--color-text-light);
  margin-bottom: var(--space-sm);
}

.card__excerpt {
  color: var(--color-text-muted);
}

/* ===== Button ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-body);
  font-size: var(--text-micro);
  letter-spacing: 0.03em;
  text-decoration: none;
  padding: 12px 24px;
  border: 1px solid var(--color-text);
  background-color: transparent;
  color: var(--color-text);
  border-radius: 3px;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.btn:hover {
  background-color: var(--color-text);
  color: var(--color-bg);
  text-decoration: none;
}

.btn--subtle {
  border-color: var(--color-border-medium);
  color: var(--color-text-muted);
}

.btn--subtle:hover {
  border-color: var(--color-text);
  background-color: transparent;
  color: var(--color-text);
}

/* ===== Footer ===== */
.footer {
  padding: var(--space-xl) 0;
  border-top: 1px solid var(--color-border);
  margin-top: auto;
}

.footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.footer__copy {
  font-size: var(--text-micro);
  color: var(--color-text-light);
}

.footer__links {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.footer__link {
  font-size: var(--text-micro);
  color: var(--color-text-light);
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer__link:hover {
  color: var(--color-text);
  text-decoration: none;
}

/* Footer Social Icons */
.footer__social {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.footer__social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  color: var(--color-text-light);
  text-decoration: none;
  border-radius: 50%;
  transition: color 0.2s ease, background-color 0.2s ease;
}

.footer__social-link:hover {
  color: var(--color-text);
  background-color: var(--color-bg-warm);
  text-decoration: none;
}

.footer__social-link svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* ===== Contact Page ===== */
.contact-info {
  margin-top: var(--space-lg);
}

.contact-item {
  margin-bottom: var(--space-md);
}

.contact-item__label {
  font-size: var(--text-micro);
  color: var(--color-text-light);
  margin-bottom: var(--space-xs);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.contact-item__value {
  font-size: var(--text-lead);
}

.contact-item__value a {
  text-decoration: none;
}

.contact-item__value a:hover {
  text-decoration: underline;
}

/* ===== Contact Form ===== */
.contact-form {
  margin-top: var(--space-lg);
}

.form-group {
  margin-bottom: var(--space-md);
}

.form-label {
  display: block;
  font-size: var(--text-micro);
  color: var(--color-text-muted);
  margin-bottom: var(--space-xs);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.form-input,
.form-textarea {
  width: 100%;
  max-width: 500px;
  padding: 12px 16px;
  font-family: var(--font-body);
  font-size: var(--text-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border-medium);
  border-radius: 4px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-text-muted);
  box-shadow: 0 0 0 3px rgba(0, 0, 0, 0.03);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--color-text-light);
}

.form-textarea {
  min-height: 150px;
  resize: vertical;
}

/* Select Dropdown */
.form-input[type="text"],
.form-input[type="email"],
select.form-input {
  appearance: none;
  -webkit-appearance: none;
  -moz-appearance: none;
}

select.form-input {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236B6B6B' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 16px center;
  padding-right: 40px;
  cursor: pointer;
}

select.form-input:focus {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%232C2C2C' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
}

.form-submit {
  margin-top: var(--space-md);
}

.form-note {
  margin-top: var(--space-sm);
  font-size: var(--text-micro);
  color: var(--color-text-light);
}

/* Form Success/Error States */
.form-message {
  padding: var(--space-md);
  border-radius: 4px;
  margin-bottom: var(--space-md);
}

.form-message--success {
  background-color: rgba(76, 175, 80, 0.1);
  border: 1px solid rgba(76, 175, 80, 0.3);
  color: #2e7d32;
}

.form-message--error {
  background-color: rgba(244, 67, 54, 0.1);
  border: 1px solid rgba(244, 67, 54, 0.3);
  color: #c62828;
}

/* ===== Projects List ===== */
.project-list {
  margin-top: var(--space-xl);
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

/* Project Card (LinkedIn-style) */
.project-card {
  padding: var(--space-lg);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border-medium);
  border-radius: 8px;
}

.project-card__header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-sm);
}

.project-card__title {
  font-family: var(--font-heading);
  font-size: var(--text-h3);
  font-weight: 500;
  color: var(--color-text);
  margin: 0;
}

.project-card__meta {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.project-card__date {
  font-size: var(--text-micro);
  color: var(--color-text-light);
}

.project-card__description {
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
  max-width: var(--max-width-prose);
}

.project-card__details {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.project-card__detail {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.project-card__label {
  font-size: var(--text-micro);
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.project-card__value {
  font-size: var(--text-body);
  color: var(--color-text-muted);
}

/* Legacy project-item styles (kept for backwards compatibility) */
.project-item {
  padding: var(--space-lg) 0;
  border-bottom: 1px solid var(--color-border);
}

.project-item:first-child {
  border-top: 1px solid var(--color-border);
}

.project-item__link {
  text-decoration: none;
  display: block;
}

.project-item__link:hover .project-item__title {
  color: var(--color-text-muted);
}

.project-item__title {
  font-family: var(--font-heading);
  font-size: var(--text-h3);
  font-weight: 400;
  margin-bottom: var(--space-xs);
  transition: color 0.2s ease;
}

.project-item__meta {
  font-size: var(--text-micro);
  color: var(--color-text-light);
  margin-bottom: var(--space-sm);
}

.project-item__excerpt {
  color: var(--color-text-muted);
  max-width: var(--max-width-prose);
}

/* ===== Work Pages ===== */
.work-intro {
  margin-bottom: var(--space-section);
}

.work-section {
  margin-bottom: var(--space-xl);
}

.work-section__title {
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
}

.work-list {
  list-style: none;
}

.work-list__item {
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-muted);
}

.work-list__item:last-child {
  border-bottom: none;
}

/* ===== Warm Band (Visual Breathing Space) ===== */
.warm-band {
  background-color: var(--color-bg-warm);
  padding: var(--space-section) 0;
  margin-top: var(--space-section);
}

.warm-band--subtle {
  background-color: var(--color-bg-warm-deep);
}

/* ===== Portrait Placeholder ===== */
.portrait-container {
  width: 120px;
  height: 150px;
  background-color: var(--color-bg-warm);
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.portrait-container--large {
  width: 180px;
  height: 225px;
}

.portrait-placeholder {
  font-size: var(--text-micro);
  color: var(--color-text-light);
}

/* ===== Responsive Design ===== */

/* Tablet */
@media (max-width: 1024px) {
  :root {
    --header-height: 70px;
  }

  .container {
    padding: 0 var(--space-md);
  }
}

/* Mobile */
@media (max-width: 768px) {
  :root {
    --header-height: 60px;
  }

  /* Header Mobile */
  .header__right {
    gap: var(--space-sm);
  }

  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-bg);
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-lg);
    gap: var(--space-sm);
    transform: translateX(-100%);
    transition: transform 0.3s ease;
    z-index: 99;
  }

  .nav.is-open {
    transform: translateX(0);
  }

  .nav__link {
    font-size: var(--text-body);
    padding: var(--space-sm) 0;
  }

  .nav-toggle {
    display: block;
  }

  /* Page Content Mobile */
  .page-content > h1 + * {
    margin-top: 1.6rem;
  }

  /* Hero Mobile */
  .hero {
    padding: var(--space-xl) 0;
  }

  .hero__inner {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }

  .hero__portrait {
    order: -1;
    justify-content: center;
  }

  .hero__portrait-wrapper {
    max-width: 280px;
  }

  .hero__lead {
    font-size: var(--text-body);
  }

  /* Footer Mobile */
  .footer__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-md);
  }
}

/* Small Mobile */
@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-sm);
  }

  .lang-switch {
    font-size: 0.75rem;
  }
}

/* ===== Print Styles ===== */
@media print {
  .header,
  .footer,
  .nav-toggle {
    display: none;
  }

  .main {
    padding-top: 0;
  }

  a {
    text-decoration: none;
  }
}

/* ===== Accessibility ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}

/* Focus Styles */
:focus-visible {
  outline: 2px solid var(--color-text);
  outline-offset: 3px;
}

/* Skip Link */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background-color: var(--color-text);
  color: var(--color-bg);
  text-decoration: none;
  z-index: 1000;
  border-radius: 3px;
}

.skip-link:focus {
  top: var(--space-sm);
}