/* ===================================================
   星忆 Xingyi Official Website — style.css
   =================================================== */

/* ---------------------------------------------------
   1. CSS Variables (Brand Tokens)
   --------------------------------------------------- */
:root {
  /* Primary palette */
  --color-primary: #5c6bc0;
  --color-primary-dark: #3949ab;
  --color-primary-brand: #1a237e;
  --color-primary-light: #e8eaf6;
  --color-primary-surface: #f5f6ff;

  /* Gold accent */
  --color-gold: #FFD700;

  /* Backgrounds */
  --color-bg: #f8f9fa;
  --color-surface: #ffffff;

  /* Borders */
  --color-border: #e9ecef;

  /* Text */
  --color-text: #212529;
  --color-text-secondary: #495057;
  --color-text-muted: #868e96;

  /* Spacing */
  --container-max: 1200px;
  --container-px: 24px;

  /* Radius */
  --radius-card: 12px;
  --radius-btn: 10px;
  --radius-btn-sm: 8px;

  /* Shadows */
  --shadow-nav: 0 2px 8px rgba(0, 0, 0, 0.08);
  --shadow-card: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-card-hover: 0 8px 24px rgba(92, 107, 192, 0.2);
  --shadow-btn: 0 4px 12px rgba(92, 107, 192, 0.4);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.2s ease;

  /* Nav height */
  --nav-height: 64px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

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

ul {
  list-style: none;
}

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

/* ---------------------------------------------------
   3. Container
   --------------------------------------------------- */
.container {
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-px);
}

/* ---------------------------------------------------
   4. Buttons
   --------------------------------------------------- */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--color-primary);
  color: #fff;
  font-size: 1rem;
  font-weight: 600;
  padding: 14px 28px;
  border-radius: var(--radius-btn);
  border: 2px solid transparent;
  text-decoration: none;
  cursor: pointer;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  transition: background var(--transition-normal), box-shadow var(--transition-normal);
  white-space: nowrap;
}

.btn-primary:active {
  transform: scale(0.97);
  background: var(--color-primary-dark);
}

.btn-primary:focus-visible {
  outline: 2px solid #9fa8da;
  outline-offset: 2px;
}

.btn-primary:disabled,
.btn-primary[aria-disabled="true"] {
  background: #adb5bd;
  cursor: not-allowed;
  pointer-events: none;
}

@media (hover: hover) {
  .btn-primary:hover {
    background: var(--color-primary-dark);
    box-shadow: var(--shadow-btn);
  }
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: transparent;
  color: var(--color-primary);
  font-size: 1rem;
  font-weight: 600;
  padding: 14px 28px;
  border-radius: var(--radius-btn);
  border: 2px solid var(--color-primary);
  text-decoration: none;
  cursor: pointer;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  transition: background var(--transition-normal);
  white-space: nowrap;
}

.btn-secondary:active {
  transform: scale(0.97);
  background: var(--color-primary-light);
}

.btn-secondary:focus-visible {
  outline: 2px solid #9fa8da;
  outline-offset: 2px;
}

@media (hover: hover) {
  .btn-secondary:hover {
    background: var(--color-primary-light);
  }
}

.btn--sm {
  font-size: 0.875rem;
  padding: 8px 18px;
  border-radius: var(--radius-btn-sm);
}

.btn-icon {
  flex-shrink: 0;
}

/* ---------------------------------------------------
   5. Section Common
   --------------------------------------------------- */
.section-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-text);
  text-align: center;
  margin-bottom: 12px;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  text-align: center;
  margin-bottom: 48px;
}

/* ---------------------------------------------------
   6. Nav Bar
   --------------------------------------------------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  transition: box-shadow var(--transition-normal);
}

.nav.nav--scrolled {
  box-shadow: var(--shadow-nav);
}

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

.nav__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-primary-brand);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}

.nav__logo {
  border-radius: 8px;
  flex-shrink: 0;
}

.nav__name {
  color: var(--color-primary-brand);
}

.nav__name-en {
  font-style: italic;
  color: var(--color-text-secondary);
  font-size: 0.9em;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav__link {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  transition: color var(--transition-fast);
}

.nav__link:active {
  color: var(--color-primary-dark);
}

@media (hover: hover) {
  .nav__link:hover {
    color: var(--color-primary);
  }
}

/* Hamburger */
.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
  border-radius: 6px;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  cursor: pointer;
}

.nav__hamburger:active {
  transform: scale(0.9);
}

@media (hover: hover) {
  .nav__hamburger:hover {
    opacity: 0.7;
  }
}

.hamburger__bar {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

/* Open state */
.nav__hamburger.is-open .hamburger__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav__hamburger.is-open .hamburger__bar:nth-child(2) {
  opacity: 0;
}

.nav__hamburger.is-open .hamburger__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* Mobile menu */
.nav__mobile-menu {
  display: none;
  flex-direction: column;
  position: absolute;
  top: var(--nav-height);
  left: 0;
  right: 0;
  background: var(--color-surface);
  box-shadow: var(--shadow-nav);
  padding: 16px var(--container-px) 24px;
  gap: 4px;
  border-top: 1px solid var(--color-border);
}

.nav__mobile-menu.is-open {
  display: flex;
}

.nav__mobile-link {
  font-size: 1rem;
  color: var(--color-text-secondary);
  padding: 12px 0;
  border-bottom: 1px solid var(--color-border);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}

.nav__mobile-link:last-of-type {
  border-bottom: none;
}

.nav__mobile-link:active {
  color: var(--color-primary-dark);
}

@media (hover: hover) {
  .nav__mobile-link:hover {
    color: var(--color-primary);
  }
}

.nav__mobile-cta {
  margin-top: 12px;
  text-align: center;
  justify-content: center;
}

/* Responsive Nav */
@media (max-width: 767px) {
  .nav__links {
    display: none;
  }

  .nav__hamburger {
    display: flex;
  }
}

/* ---------------------------------------------------
   7. Hero Section
   --------------------------------------------------- */
.hero {
  background: linear-gradient(135deg, var(--color-primary-brand) 0%, #283593 60%, #3949ab 100%);
  color: #fff;
  padding: 80px 0 72px;
  overflow: hidden;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.hero__brand {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.hero__icon {
  border-radius: 14px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

.hero__brand-name {
  font-size: 1.3rem;
  font-weight: 600;
  color: #c5cae9;
}

.hero__brand-name em {
  font-style: italic;
  color: #fff;
}

.hero__title {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  color: #fff;
}

.hero__subtitle {
  font-size: 1.1rem;
  color: #c5cae9;
  line-height: 1.7;
  margin-bottom: 36px;
  max-width: 440px;
}

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

.hero__btn-download {
  background: var(--color-primary);
}

@media (hover: hover) {
  .hero__btn-download:hover {
    background: #4557b0;
  }
}

.hero__btn-try {
  border-color: rgba(255,255,255,0.5);
  color: #fff;
}

.hero__btn-try:active {
  background: rgba(255,255,255,0.1);
}

@media (hover: hover) {
  .hero__btn-try:hover {
    background: rgba(255,255,255,0.1);
    border-color: #fff;
  }
}

/* Hero visual */
.hero__visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero__mockup {
  width: 100%;
  max-width: 360px;
  background: rgba(255,255,255,0.08);
  border-radius: 20px;
  border: 1px solid rgba(255,255,255,0.15);
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
  overflow: hidden;
  aspect-ratio: 4 / 3;
}

.mockup__screen {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(180deg, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0.02) 100%);
}

.mockup__placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 24px;
  text-align: center;
}

.mockup__icon {
  border-radius: 18px;
  opacity: 0.85;
}

.mockup__text {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.5);
}

/* Hero responsive */
@media (max-width: 767px) {
  .hero {
    padding: 52px 0 48px;
  }

  .hero__inner {
    grid-template-columns: 1fr;
    gap: 36px;
    text-align: center;
  }

  .hero__brand {
    justify-content: center;
  }

  .hero__title {
    font-size: 2rem;
  }

  .hero__subtitle {
    font-size: 1rem;
    margin-inline: auto;
  }

  .hero__actions {
    justify-content: center;
  }

  .hero__visual {
    order: -1;
  }

  .hero__mockup {
    max-width: 280px;
  }
}

/* ---------------------------------------------------
   8. Features Section
   --------------------------------------------------- */
.features {
  padding: 80px 0;
  background: var(--color-bg);
}

.features__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 28px 24px;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}

.feature-card:active {
  background: var(--color-bg);
  transform: scale(0.98);
}

@media (hover: hover) {
  .feature-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-card);
  }
}

.feature-card__icon {
  margin-bottom: 16px;
}

.feature-card__title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 8px;
}

.feature-card__desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.65;
}

@media (max-width: 1023px) {
  .features__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 767px) {
  .features {
    padding: 60px 0;
  }

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

/* ---------------------------------------------------
   9. Download Section
   --------------------------------------------------- */
.download {
  padding: 80px 0;
  background: var(--color-surface);
}

.download__grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
  margin-bottom: 24px;
}

.download-card {
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 20px 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  transition: border-color var(--transition-normal), box-shadow var(--transition-normal), transform var(--transition-fast);
}

.download-card:active {
  transform: scale(0.97);
  background: var(--color-primary-surface);
  border-color: var(--color-primary-dark);
}

@media (hover: hover) {
  .download-card:hover {
    border-color: var(--color-primary);
    box-shadow: 0 4px 12px rgba(92, 107, 192, 0.2);
  }
}

.download-card:focus-within {
  border-color: var(--color-primary);
  outline: 2px solid #9fa8da;
  outline-offset: 2px;
}

/* Recommended card */
.download-card--recommended {
  border-color: var(--color-primary);
  background: var(--color-primary-surface);
}

/* Unavailable card */
.download-card--unavailable {
  background: var(--color-bg);
  cursor: default;
}

.download-card--unavailable:active {
  transform: none;
  background: var(--color-bg);
  border-color: var(--color-border);
}

@media (hover: hover) {
  .download-card--unavailable:hover {
    border-color: var(--color-border);
    box-shadow: none;
  }
}

.download-card__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.download-card__platform {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--color-text);
}

.download-card--unavailable .download-card__platform {
  color: var(--color-text-muted);
}

.platform-icon {
  color: var(--color-primary);
  flex-shrink: 0;
}

.download-card--unavailable .platform-icon {
  color: var(--color-text-muted);
}

.download-card__badge {
  background: var(--color-primary);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 20px;
  white-space: nowrap;
}

.download-card__version {
  font-size: 0.82rem;
  color: var(--color-text-muted);
  min-height: 1.2em;
}

.download-card__btn {
  justify-content: center;
  font-size: 0.875rem;
  padding: 10px 16px;
  border-radius: var(--radius-btn-sm);
  width: 100%;
}

.download__fallback {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  padding: 12px;
}

.download__fallback a {
  color: var(--color-primary);
  text-decoration: underline;
}

.download__web-cta {
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  margin-top: 16px;
}

.download__web-cta a {
  color: var(--color-primary);
  font-weight: 600;
}

@media (hover: hover) {
  .download__web-cta a:hover {
    text-decoration: underline;
  }
}

@media (max-width: 1023px) {
  .download__grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 767px) {
  .download {
    padding: 60px 0;
  }

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

@media (max-width: 479px) {
  .download__grid {
    grid-template-columns: 1fr;
  }

  .download-card__btn {
    padding: 12px 16px;
  }
}

/* ---------------------------------------------------
   10. Quick Start Section
   --------------------------------------------------- */
.quickstart {
  padding: 80px 0;
  background: var(--color-primary-light);
}

.quickstart__steps {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  gap: 16px;
  align-items: start;
  margin-top: 8px;
}

.quickstart__step {
  background: var(--color-surface);
  border-radius: var(--radius-card);
  padding: 32px 24px;
  text-align: center;
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.step__number {
  width: 36px;
  height: 36px;
  background: var(--color-primary);
  color: #fff;
  font-size: 1rem;
  font-weight: 700;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.step__icon {
  margin: 4px 0;
}

.step__title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-text);
}

.step__desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.65;
}

.quickstart__arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: 60px;
  color: var(--color-text-muted);
}

@media (max-width: 767px) {
  .quickstart {
    padding: 60px 0;
  }

  .quickstart__steps {
    grid-template-columns: 1fr;
    max-width: 400px;
    margin-inline: auto;
  }

  .quickstart__arrow {
    padding-top: 0;
    transform: rotate(90deg);
    justify-self: center;
  }
}

/* ---------------------------------------------------
   11. FAQ Section
   --------------------------------------------------- */
.faq {
  padding: 80px 0;
  background: var(--color-bg);
}

.faq__list {
  max-width: 720px;
  margin-inline: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  overflow: hidden;
  background: var(--color-surface);
}

.faq__item {
  border-bottom: 1px solid var(--color-border);
}

.faq__item:last-child {
  border-bottom: none;
}

.faq__header {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 18px 20px;
  font-size: 0.97rem;
  font-weight: 600;
  color: var(--color-text);
  text-align: left;
  background: var(--color-surface);
  cursor: pointer;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.faq__header:active {
  background: #f1f3f5;
}

.faq__header[aria-expanded="true"] {
  background: var(--color-bg);
  color: var(--color-primary);
}

@media (hover: hover) {
  .faq__header:hover {
    background: var(--color-bg);
  }
}

.faq__arrow {
  flex-shrink: 0;
  color: var(--color-text-muted);
  transition: transform var(--transition-normal);
}

.faq__header[aria-expanded="true"] .faq__arrow {
  transform: rotate(180deg);
  color: var(--color-primary);
}

.faq__panel {
  padding: 0 20px 20px;
  background: var(--color-bg);
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.faq__panel p {
  margin-bottom: 8px;
}

.faq__panel p:last-child {
  margin-bottom: 0;
}

.faq__panel ul {
  list-style: disc;
  padding-left: 20px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.faq__panel code {
  font-family: 'SFMono-Regular', Consolas, monospace;
  background: var(--color-border);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.85em;
  color: var(--color-primary-dark);
}

@media (max-width: 767px) {
  .faq {
    padding: 60px 0;
  }
}

/* ---------------------------------------------------
   12. Footer
   --------------------------------------------------- */
.footer {
  background: #212529;
  color: var(--color-text-muted);
  padding: 40px 0;
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px;
}

.footer__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  color: #adb5bd;
}

.footer__links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.footer__link {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  transition: color var(--transition-fast);
}

.footer__link:active {
  color: #fff;
}

@media (hover: hover) {
  .footer__link:hover {
    color: #fff;
  }
}

.footer__copy {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  width: 100%;
  text-align: center;
  padding-top: 8px;
  border-top: 1px solid #343a40;
  margin-top: 8px;
}

@media (max-width: 767px) {
  .footer__inner {
    flex-direction: column;
    text-align: center;
    align-items: center;
  }

  .footer__links {
    justify-content: center;
  }
}