/* DeepSeek visual-similarity clone theme
   Source origin: https://www.deepseek.com  (zh-CN homepage)
   Tokens derived from the live DeepSeek design system. */

@font-face {
  font-family: "DM Sans";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("assets/dm-sans-400.woff2") format("woff2");
}
@font-face {
  font-family: "DM Sans";
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url("assets/dm-sans-500.woff2") format("woff2");
}
@font-face {
  font-family: "DM Sans";
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: url("assets/dm-sans-700.woff2") format("woff2");
}

:root {
  --brand: #4d6bfe;
  --brand-deep: #3a65c2;
  --brand-medium: #4176e6;
  --brand-light: #73a3d2;
  --text: #1e232c;
  --text-bluish: #152443;
  --text-link: #234792;
  --text-secondary: rgba(0, 0, 0, 0.7);
  --text-description: rgba(0, 0, 0, 0.65);
  --placeholder: #8691a1;
  --bg-page: #f9f8f8;
  --bg-surface-1: hsla(0, 0%, 100%, 0.3);
  --bg-surface-2: hsla(0, 0%, 100%, 0.2);
  --bg-surface-raised: hsla(0, 0%, 100%, 0.45);
  --bg-input: hsla(0, 0%, 100%, 0.2);
  --border-subtle: rgba(0, 0, 0, 0.06);
  --border-default: rgba(0, 0, 0, 0.1);
  --border-secondary: rgba(9, 45, 78, 0.14);
  --border-input: hsla(0, 0%, 100%, 0.2);
  --btn-primary-bg: #1a1615;
  --btn-primary-text: #fff;
  --btn-secondary-bg: hsla(0, 0%, 100%, 0.4);
  --btn-secondary-border: rgba(9, 45, 78, 0.18);
  --radius-pill: 100px;
  --radius-card: 24px;
  --radius-panel: 16px;
  --radius-media: 12px;
  --radius-input: 10px;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 40px;
  --space-8: 56px;
  --space-9: 80px;
  --space-10: 120px;
  --blur-glass: 12px;
  --shadow-card: 0 0 0 1px #f1f5f9, 0 2px 4px rgba(0, 0, 0, 0.05), 0 12px 24px rgba(0, 0, 0, 0.05);
  --font-body: "DM Sans", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  background: var(--bg-page);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- Ambient background ---------- */
.flow-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
  background: linear-gradient(rgb(156, 193, 231) 0%, rgba(250, 250, 250, 0) 62%);
}

.flow-blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(70px);
  opacity: 0.55;
}

.flow-blob-a {
  width: 520px;
  height: 520px;
  top: -180px;
  left: 50%;
  transform: translateX(-60%);
  background: radial-gradient(circle, rgba(77, 107, 254, 0.32), rgba(77, 107, 254, 0) 70%);
}

.flow-blob-b {
  width: 420px;
  height: 420px;
  top: 40px;
  right: -120px;
  background: radial-gradient(circle, rgba(115, 163, 210, 0.35), rgba(115, 163, 210, 0) 70%);
}

.flow-blob-c {
  width: 380px;
  height: 380px;
  top: 120px;
  left: -140px;
  background: radial-gradient(circle, rgba(65, 118, 230, 0.24), rgba(65, 118, 230, 0) 70%);
}

/* ---------- Header ---------- */
.site-header {
  position: relative;
  z-index: 20;
  padding: 14px 0;
}

.header-bar {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-5);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
}

.brand {
  display: inline-flex;
  align-items: center;
  color: var(--brand-medium);
  flex-shrink: 0;
}

.brand-mark svg {
  display: block;
  height: 23px;
  width: auto;
}

.nav-desktop {
  display: flex;
  align-items: center;
  gap: var(--space-5);
}

.nav-link {
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
  opacity: 0.82;
  transition: color 0.2s ease, opacity 0.2s ease;
}

.nav-link:hover {
  color: var(--brand);
  opacity: 1;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.locale-toggle {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  padding: 2px;
  border-radius: var(--radius-pill);
  background: var(--bg-surface-2);
  border: 1px solid var(--border-subtle);
}

.locale-item {
  border: 0;
  background: transparent;
  color: var(--text-description);
  font-family: inherit;
  font-size: 13px;
  padding: 5px 12px;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease;
}

.locale-item.is-active {
  background: #fff;
  color: var(--text);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

.menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 40px;
  height: 40px;
  border: 0;
  border-radius: 50%;
  background: var(--bg-surface-2);
  cursor: pointer;
}

.menu-toggle span {
  display: block;
  width: 16px;
  height: 1.5px;
  margin: 0 auto;
  background: var(--text);
}

/* ---------- Hero ---------- */
main {
  position: relative;
  z-index: 10;
}

.hero {
  max-width: 1080px;
  margin: 0 auto;
  padding: 64px 24px 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 24px;
}

.news-banner {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  max-width: 880px;
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  background: var(--bg-surface-raised);
  border: 1px solid var(--border-secondary);
  backdrop-filter: blur(var(--blur-glass));
  -webkit-backdrop-filter: blur(var(--blur-glass));
  color: var(--text);
  font-size: 14px;
  line-height: 1.4;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.news-banner:hover {
  background: #fff;
  border-color: var(--border-default);
}

.news-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--brand);
  flex-shrink: 0;
}

.news-text {
  text-align: left;
}

.news-arrow {
  flex-shrink: 0;
  color: var(--brand);
  transition: transform 0.2s ease;
}

.news-banner:hover .news-arrow {
  transform: translateX(3px);
}

.hero-title {
  position: relative;
  margin: 24px 0 0;
  font-size: clamp(30px, 5vw, 46px);
  font-weight: 400;
  line-height: 1.55;
  letter-spacing: 0.4em;
  color: var(--text-bluish);
  text-indent: 0.4em;
}

.sparkle-wrap {
  display: inline-block;
  margin-left: 4px;
  vertical-align: baseline;
}

.sparkle-wrap img {
  width: 28px;
  height: 28px;
  opacity: 0.55;
  vertical-align: -3px;
  animation: sparkle-pulse 2.6s ease-in-out infinite;
}

.hero-title:hover .sparkle-wrap img {
  opacity: 1;
}

@keyframes sparkle-pulse {
  0%, 100% { transform: scale(1); opacity: 0.5; }
  50% { transform: scale(1.18); opacity: 0.95; }
}

.hero-tags {
  display: flex;
  gap: 12px;
  justify-content: center;
}

.hero-tag {
  font-size: 14px;
  color: var(--text-description);
  padding: 4px 14px;
  border-radius: var(--radius-pill);
  background: var(--bg-surface-3, rgba(0, 0, 0, 0.03));
  border: 1px solid var(--border-subtle);
}

/* Chat card */
.hero-card {
  width: min(880px, 100%);
  margin-top: 16px;
  padding: 16px;
  border-radius: var(--radius-card);
  background: var(--bg-surface-raised);
  border: 1px solid var(--border-secondary);
  box-shadow: var(--shadow-card);
  backdrop-filter: blur(var(--blur-glass));
  -webkit-backdrop-filter: blur(var(--blur-glass));
  display: flex;
  flex-direction: column;
  gap: 12px;
  text-align: left;
}

.hero-input {
  width: 100%;
  min-height: 80px;
  max-height: 300px;
  border: 0;
  outline: none;
  resize: none;
  background: transparent;
  color: var(--text);
  font-family: inherit;
  font-size: 16px;
  line-height: 1.4;
}

.hero-input::placeholder {
  color: var(--placeholder);
}

.hero-card-foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.hero-toggles {
  display: flex;
  gap: 8px;
}

.hero-toggle {
  height: 34px;
  padding: 0 12px;
  border-radius: 18px;
  border: 1px solid var(--border-secondary);
  background: var(--bg-surface-1);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.hero-toggle.is-active {
  background: rgba(77, 107, 254, 0.12);
  border-color: rgba(77, 107, 254, 0.4);
  color: var(--brand-deep);
}

.hero-send {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  border: 0;
  background: var(--btn-primary-bg);
  color: #fff;
  font-size: 15px;
  cursor: pointer;
  transition: transform 0.2s ease;
}

.hero-send:hover {
  transform: translateX(2px);
}

/* CTA row */
.hero-cta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-top: 12px;
}

.cta-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 12px 22px;
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 500;
  transition: all 0.2s ease;
}

.cta-chip-secondary {
  background: var(--btn-secondary-bg);
  border: 1px solid var(--btn-secondary-border);
  color: var(--text);
}

.cta-chip-secondary:hover {
  background: #fff;
  border-color: var(--border-default);
}

.cta-chip-primary {
  background: var(--btn-primary-bg);
  color: var(--btn-primary-text);
  border: 1px solid transparent;
  box-shadow: 0 10px 24px rgba(26, 22, 21, 0.22);
}

.cta-chip-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 14px 30px rgba(26, 22, 21, 0.28);
}

/* ---------- Feature cards ---------- */
.features {
  max-width: 1080px;
  margin: 48px auto 0;
  padding: 0 24px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.feature-card {
  padding: 24px;
  border-radius: var(--radius-panel);
  background: var(--bg-surface-raised);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-card);
  backdrop-filter: blur(var(--blur-glass));
  -webkit-backdrop-filter: blur(var(--blur-glass));
}

.feature-title {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 500;
  color: var(--text-bluish);
}

.feature-desc {
  margin: 0;
  font-size: 14px;
  color: var(--text-description);
}

/* ---------- Guide ---------- */
.guide,
.faq {
  max-width: 880px;
  margin: 72px auto 0;
  padding: 0 24px;
}

.section-heading {
  margin: 0 0 24px;
  text-align: center;
  font-size: 28px;
  font-weight: 500;
  color: var(--text-bluish);
  letter-spacing: 0.02em;
}

.guide-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.guide-item {
  display: flex;
  gap: 16px;
  padding: 20px;
  border-radius: var(--radius-panel);
  background: #fff;
  border: 1px solid var(--border-subtle);
}

.guide-index {
  font-size: 14px;
  font-weight: 700;
  color: var(--brand);
  letter-spacing: 0.08em;
}

.guide-item h4 {
  margin: 0 0 4px;
  font-size: 16px;
  font-weight: 500;
  color: var(--text);
}

.guide-item p {
  margin: 0;
  font-size: 14px;
  color: var(--text-description);
}

/* ---------- FAQ ---------- */
.faq-list {
  display: grid;
  gap: 10px;
}

.faq-item {
  padding: 16px 20px;
  border-radius: var(--radius-panel);
  background: #fff;
  border: 1px solid var(--border-subtle);
}

.faq-item summary {
  cursor: pointer;
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  float: right;
  color: var(--brand);
}

.faq-item[open] summary::after {
  content: "–";
}

.faq-item p {
  margin: 12px 0 0;
  font-size: 14px;
  color: var(--text-description);
}

/* ---------- Footer ---------- */
.site-footer {
  margin-top: 96px;
  padding: 56px 0 32px;
  background: linear-gradient(rgba(250, 250, 250, 0), rgba(238, 240, 245, 0.9));
  border-top: 1px solid var(--border-subtle);
}

.footer-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
}

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

.footer-title {
  margin: 0 0 14px;
  font-size: 14px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.02em;
}

.footer-col {
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-link {
  font-size: 14px;
  color: var(--text-description);
  transition: color 0.2s ease;
  width: fit-content;
}

.footer-link:hover {
  color: var(--brand);
}

.footer-qr {
  margin-top: 6px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 6px;
}

.footer-qr img {
  width: 84px;
  height: 84px;
  border-radius: var(--radius-media);
  border: 1px solid var(--border-subtle);
  background: #fff;
}

.footer-qr span {
  font-size: 12px;
  color: var(--text-description);
}

.footer-bottom {
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-brand {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-bluish);
}

.footer-legal {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

.footer-legal .footer-link {
  font-size: 12px;
}

.footer-copy {
  font-size: 12px;
  color: var(--text-description);
}

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .features {
    grid-template-columns: 1fr;
  }
  .footer-columns {
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
  }
}

@media (max-width: 768px) {
  .nav-desktop {
    display: none;
  }
  .menu-toggle {
    display: flex;
  }
  .hero {
    padding-top: 40px;
  }
  .hero-title {
    letter-spacing: 0.24em;
    text-indent: 0.24em;
  }
  .news-banner {
    align-items: flex-start;
  }
  .news-text {
    font-size: 13px;
  }
  .site-header.menu-open .nav-desktop {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    position: absolute;
    top: 64px;
    left: 16px;
    right: 16px;
    padding: 16px;
    gap: 14px;
    border-radius: var(--radius-panel);
    background: #fff;
    box-shadow: var(--shadow-card);
  }
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}