/* ============================================================
   DeepTweet landing page styles
   Design language adapted from immersivetranslate.com
   (see docs/research/immersive-translate/DESIGN_TOKENS.md)
   ============================================================ */

:root {
  /* Colors — immersive-translate palette */
  --c-navy: #0b354d;          /* big headings */
  --c-ink: #333333;           /* headings / body-strong */
  --c-gray: #545454;          /* secondary text */
  --c-pink: #ea4c89;          /* accent words */
  --c-blue: #30a1e1;          /* brand bright blue */
  --c-link: #1677ff;          /* text links */
  --c-blue-tint: #cee7ff;
  --c-line: #e5e7eb;          /* hairline borders */
  --c-panel: #f7f8fa;         /* light panel bg */
  --c-bg: #ffffff;
  --c-footer-bg: #111111;
  --c-footer-text: #d6d9db;
  --c-footer-muted: #8b98a5;

  /* Pastel blobs */
  --blob-blue: rgba(196, 231, 255, 0.9);
  --blob-lavender: rgba(207, 205, 255, 0.55);
  --blob-pink: rgba(255, 194, 218, 0.55);
  --blob-mint: rgba(203, 246, 214, 0.55);

  /* Gradients */
  --grad-hero: radial-gradient(circle at 50% 28%, #e2f5fe 0%, #9ac9e4 100%);
  --grad-cta: linear-gradient(180deg, #edfafF 0%, #9fd5ff 100%);
  --grad-glow: linear-gradient(100deg, #7c6cff 0%, #30a1e1 45%, #ea4c89 100%);

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2.5rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;

  /* Shape */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 24px;

  /* Layout */
  --container-max: 1120px;
  --container-narrow-max: 760px;

  /* Type */
  --font-stack: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI",
    Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Noto Sans CJK SC", sans-serif,
    "Apple Color Emoji", "Segoe UI Emoji";

  --shadow-card: 0 1px 2px rgba(11, 53, 77, 0.04), 0 8px 24px rgba(11, 53, 77, 0.06);
  --shadow-card-hover: 0 2px 4px rgba(11, 53, 77, 0.05), 0 16px 36px rgba(11, 53, 77, 0.1);
  --shadow-frame: 0 12px 40px rgba(11, 53, 77, 0.16);
  --shadow-btn-white: 0 4px 14px rgba(11, 53, 77, 0.12);
}

/* ---------- Reset & base ---------- */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-stack);
  font-size: 16px;
  line-height: 1.5;
  color: var(--c-ink);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: var(--c-link);
  text-decoration: none;
  transition: color 0.15s ease;
}

a:hover {
  text-decoration: underline;
}

h1,
h2,
h3 {
  line-height: 1.2;
  margin: 0 0 var(--space-md);
  font-weight: 600;
  color: var(--c-navy);
}

p {
  margin: 0 0 var(--space-md);
}

/* Pink accent words inside headings */
.accent {
  color: var(--c-pink);
}

/* ---------- i18n language switch ---------- */

html[data-lang="zh"] .i18n-en {
  display: none;
}

html[data-lang="en"] .i18n-zh {
  display: none;
}

/* ---------- Layout helpers ---------- */

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

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

.section {
  padding: var(--space-3xl) 0;
}

.section-alt {
  background: var(--c-panel);
}

.section-title {
  font-size: clamp(1.5rem, 3.2vw, 2.25rem);
  font-weight: 500;
  color: var(--c-ink);
  text-align: center;
}

.section-subtitle {
  text-align: center;
  color: var(--c-gray);
  max-width: 42rem;
  margin: 0 auto var(--space-2xl);
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-md);
  font-weight: 500;
  font-size: 1rem;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease,
    border-color 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease;
  white-space: nowrap;
}

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

/* Black pill — the signature primary action */
.btn-primary {
  background: linear-gradient(#1a1a1c, #000);
  color: #fff;
  border-radius: 999px;
  font-weight: 600;
  letter-spacing: 0.01em;
}

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

/* Gradient border ring + soft colored shadow (crisp, not a blurred blob) */
.glow-btn {
  background: linear-gradient(#1a1a1c, #000) padding-box,
    var(--grad-glow) border-box;
  border: 2px solid transparent;
  box-shadow: 0 8px 24px rgba(48, 161, 225, 0.35),
    0 2px 8px rgba(124, 108, 255, 0.25);
}

.glow-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(48, 161, 225, 0.45),
    0 4px 12px rgba(234, 76, 137, 0.3);
}

/* Chrome logo inside primary buttons */
.chrome-ic {
  flex-shrink: 0;
  display: block;
}

/* White pill secondary */
.btn-outline {
  background: #fff;
  color: var(--c-navy);
  border-color: var(--c-line);
  border-radius: 999px;
  box-shadow: var(--shadow-btn-white);
}

.btn-outline:hover {
  border-color: var(--c-blue);
  color: var(--c-blue);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(11, 53, 77, 0.16);
}

.btn-ghost {
  background: transparent;
  border-color: var(--c-line);
  color: var(--c-gray);
  padding: 0.4rem 0.9rem;
  font-size: 0.9rem;
}

.btn-ghost:hover {
  border-color: var(--c-blue);
  color: var(--c-blue);
}

.btn-light {
  background: linear-gradient(#1a1a1c, #000);
  color: #fff;
  border-radius: 999px;
  font-weight: 600;
  letter-spacing: 0.01em;
}

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

.btn-lg {
  padding: 0.95rem 2.1rem;
  font-size: 1.05rem;
  border-radius: 999px;
}

/* ---------- Header / nav ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(229, 231, 235, 0.8);
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  height: 60px;
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  color: var(--c-ink);
  font-weight: 700;
  font-size: 1rem;
}

.nav-brand:hover {
  text-decoration: none;
}

.nav-brand img {
  border-radius: var(--radius-sm);
}

.nav-links {
  display: flex;
  gap: var(--space-xs);
  margin-left: auto;
}

.nav-links a {
  color: var(--c-ink);
  font-size: 1rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: 10px;
  transition: color 0.15s ease, background-color 0.15s ease;
}

.nav-links a:hover {
  color: var(--c-blue);
  background: rgba(48, 161, 225, 0.08);
  text-decoration: none;
}

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

/* ---------- Hero ---------- */

.hero {
  position: relative;
  padding: var(--space-3xl) 0 0;
  background: var(--grad-hero);
  overflow: hidden;
}

/* fade the gradient into white at the bottom, like the reference */
.hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 120px;
  background: linear-gradient(to top, #fff 0%, rgba(237, 250, 255, 0) 100%);
  pointer-events: none;
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero-grid {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.hero-copy {
  max-width: 800px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.hero-badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.55);
  border: 1px solid rgba(255, 255, 255, 0.8);
  color: var(--c-navy);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 0.3rem 1rem;
  border-radius: 999px;
  margin-bottom: var(--space-lg);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}

.hero-title {
  font-size: clamp(1.5rem, 4.2vw, 3rem);
  font-weight: 600;
  color: var(--c-navy);
  letter-spacing: -0.01em;
  margin-bottom: var(--space-lg);
}

.hero-subtitle {
  font-size: 1rem;
  color: var(--c-ink);
  max-width: 640px;
  margin-bottom: var(--space-xl);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.hero-note {
  color: var(--c-navy);
  font-size: 0.9rem;
  opacity: 0.75;
  margin: 0;
}

/* Glass strip under the hero CTAs */
.glass-strip {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-lg) var(--space-2xl);
  margin-top: var(--space-2xl);
  background: rgba(255, 255, 255, 0.4);
  border: 1px solid rgba(255, 255, 255, 0.55);
  border-radius: var(--radius-xl);
  padding: 1rem 2.5rem;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.glass-strip .glass-item {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  color: var(--c-navy);
  font-size: 0.95rem;
  font-weight: 500;
}

.hero-media {
  margin-top: var(--space-2xl);
  width: 100%;
  max-width: 920px;
  padding-bottom: var(--space-2xl);
}

/* Pastel blob glow behind media */
.blob {
  position: relative;
  z-index: 0;
}

.blob::before {
  content: "";
  position: absolute;
  inset: -10% -14%;
  background:
    radial-gradient(closest-side, var(--blob-blue), transparent 72%),
    radial-gradient(closest-side, var(--blob-lavender), transparent 70%);
  background-position:
    30% 40%,
    75% 65%;
  background-size: 85% 85%, 60% 60%;
  background-repeat: no-repeat;
  filter: blur(48px);
  border-radius: 48px;
  z-index: -1;
}

.blob-pink::before {
  background:
    radial-gradient(closest-side, var(--blob-pink), transparent 72%),
    radial-gradient(closest-side, var(--blob-blue), transparent 70%);
  background-position:
    65% 35%,
    30% 70%;
  background-size: 85% 85%, 60% 60%;
  background-repeat: no-repeat;
}

.blob-mint::before {
  background:
    radial-gradient(closest-side, var(--blob-mint), transparent 72%),
    radial-gradient(closest-side, var(--blob-blue), transparent 70%);
  background-position:
    35% 60%,
    70% 30%;
  background-size: 85% 85%, 60% 60%;
  background-repeat: no-repeat;
}

/* Browser-frame decoration */
.browser-frame {
  position: relative;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-frame);
  background: #fff;
}

.browser-chrome {
  display: flex;
  gap: 6px;
  padding: 10px 12px;
  background: var(--c-panel);
  border-bottom: 1px solid var(--c-line);
}

.browser-dot {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--c-line);
}

.browser-dot:nth-child(1) {
  background: #ff5f57;
}

.browser-dot:nth-child(2) {
  background: #febc2e;
}

.browser-dot:nth-child(3) {
  background: #28c840;
}

/* ---------- Providers marquee ---------- */

.providers {
  padding: var(--space-xl) 0;
  background: #fff;
  overflow: hidden;
}

.providers-label {
  text-align: center;
  color: var(--c-gray);
  font-size: 0.85rem;
  margin-bottom: var(--space-lg);
}

.marquee {
  overflow: hidden;
  -webkit-mask-image: linear-gradient(
    to right,
    transparent,
    #000 12%,
    #000 88%,
    transparent
  );
  mask-image: linear-gradient(
    to right,
    transparent,
    #000 12%,
    #000 88%,
    transparent
  );
}

.marquee-track {
  display: flex;
  align-items: center;
  gap: 3.5rem;
  width: max-content;
  animation: marquee 32s linear infinite;
}

.marquee-track span {
  color: #9ca3af;
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  white-space: nowrap;
}

@keyframes marquee {
  from {
    transform: translateX(0);
  }
  to {
    transform: translateX(-50%);
  }
}

/* ---------- Cards ---------- */

.card-grid {
  display: grid;
  gap: var(--space-lg);
}

.card-grid-5 {
  grid-template-columns: repeat(6, 1fr);
}

.card-grid-5 .card {
  grid-column: span 2;
}

/* 5 cards: 3 on first row, 2 centered on second row */
.card-grid-5 .card:nth-child(4) {
  grid-column: 2 / span 2;
}

.card-grid-5 .card:nth-child(5) {
  grid-column: 4 / span 2;
}

.card-grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.card {
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-card);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

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

/* Pastel icon chip, cycling through the blob palette */
.card-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 14px;
  background: var(--blob-blue);
  color: var(--c-navy);
  margin-bottom: var(--space-md);
}

/* Inline stroke icons (feather-style, platform-independent) */
.ic {
  display: block;
  width: 22px;
  height: 22px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex-shrink: 0;
}

.glass-strip .ic {
  width: 18px;
  height: 18px;
}

.card:nth-child(3n + 2) .card-icon {
  background: var(--blob-pink);
}

.card:nth-child(3n + 3) .card-icon {
  background: var(--blob-mint);
}

.card:nth-child(4n + 4) .card-icon {
  background: var(--blob-lavender);
}

.card h3 {
  font-size: 1.15rem;
  color: var(--c-navy);
}

.card p {
  color: var(--c-gray);
  font-size: 0.95rem;
  margin: 0;
}

.section-alt .card {
  background: var(--c-bg);
}

/* ---------- Showcase ---------- */

.showcase-row {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: var(--space-2xl);
  align-items: center;
  padding: var(--space-2xl) 0;
}

.showcase-row + .showcase-row {
  border-top: 1px solid var(--c-line);
}

.showcase-row-reverse .showcase-text {
  order: 2;
}

.showcase-row-reverse .showcase-media {
  order: 1;
}

.showcase-text h3 {
  font-size: clamp(1.35rem, 2.4vw, 1.875rem);
  font-weight: 600;
  color: var(--c-navy);
}

.showcase-text p {
  color: var(--c-gray);
  margin: 0;
}

.showcase-media img {
  position: relative;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-frame);
}

.showcase-media-pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

/* ---------- Quick start steps ---------- */

.steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
  counter-reset: step;
}

.step {
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-card);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

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

.step-number {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--c-navy);
  color: #fff;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
}

.step h3 {
  font-size: 1.1rem;
  color: var(--c-navy);
}

.step p {
  color: var(--c-gray);
  font-size: 0.95rem;
  margin: 0;
}

/* ---------- Privacy strip ---------- */

.privacy-strip {
  background: linear-gradient(180deg, #edfafF 0%, #d6efff 100%);
}

.privacy-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
}

.privacy-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  background: rgba(255, 255, 255, 0.65);
  border: 1px solid rgba(255, 255, 255, 0.8);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.privacy-icon {
  color: var(--c-navy);
  display: flex;
  padding-top: 2px;
}

.privacy-item p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--c-navy);
}

.privacy-more {
  text-align: center;
  margin: var(--space-xl) 0 0;
  font-weight: 600;
}

.privacy-more a {
  color: var(--c-navy);
}

/* ---------- FAQ ---------- */

.faq-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.faq-item {
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-md);
  padding: 0;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.faq-item:hover {
  border-color: var(--c-blue-tint);
}

.faq-item[open] {
  box-shadow: var(--shadow-card);
}

.faq-item summary {
  cursor: pointer;
  list-style: none;
  padding: var(--space-lg);
  font-weight: 600;
  color: var(--c-navy);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.faq-item summary::after {
  content: "+";
  color: var(--c-pink);
  font-size: 1.3rem;
  font-weight: 400;
  margin-left: var(--space-md);
  flex-shrink: 0;
}

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

.faq-answer {
  padding: 0 var(--space-lg) var(--space-lg);
  color: var(--c-gray);
}

.faq-answer p {
  margin: 0;
}

/* ---------- Bottom CTA ---------- */

.cta-section {
  background: var(--grad-cta);
  padding: var(--space-3xl) 0;
}

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

.cta-inner h2 {
  font-size: clamp(1.6rem, 3.4vw, 2.5rem);
  color: var(--c-navy);
}

.cta-inner p {
  color: rgba(11, 53, 77, 0.75);
  margin-bottom: var(--space-xl);
}

/* ---------- Footer ---------- */

.site-footer {
  background: var(--c-footer-bg);
  color: var(--c-footer-text);
  padding: var(--space-2xl) 0;
}

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

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-weight: 700;
}

.footer-brand img {
  border-radius: var(--radius-sm);
}

.footer-links {
  display: flex;
  gap: var(--space-lg);
  margin-left: auto;
}

.footer-links a {
  color: var(--c-footer-text);
  font-size: 0.95rem;
}

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

.footer-legal {
  width: 100%;
  margin: 0;
  color: var(--c-footer-muted);
  font-size: 0.85rem;
}

/* ---------- Scroll reveal ---------- */

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

.reveal.is-visible {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .marquee-track {
    animation: none;
  }
}

/* ---------- Responsive ---------- */

@media (max-width: 900px) {
  .hero-title {
    font-size: clamp(1.5rem, 5.5vw, 2.1rem);
  }

  .card-grid-5,
  .card-grid-3,
  .steps,
  .privacy-grid {
    grid-template-columns: 1fr 1fr;
  }

  .card-grid-5 .card,
  .card-grid-5 .card:nth-child(4),
  .card-grid-5 .card:nth-child(5) {
    grid-column: auto;
  }

  .card-grid-5 .card:nth-child(5) {
    grid-column: 1 / -1;
  }

  .showcase-row,
  .showcase-row-reverse {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }

  .showcase-row-reverse .showcase-text {
    order: 0;
  }

  .showcase-row-reverse .showcase-media {
    order: 1;
  }
}

@media (max-width: 620px) {
  .section {
    padding: var(--space-2xl) 0;
  }

  .section-title {
    font-size: 1.6rem;
  }

  .nav {
    height: auto;
    flex-wrap: wrap;
    padding-top: var(--space-sm);
    padding-bottom: var(--space-sm);
    gap: var(--space-sm);
  }

  .nav-links {
    order: 3;
    width: 100%;
    margin-left: 0;
    justify-content: center;
  }

  .nav-actions {
    margin-left: auto;
  }

  .nav-actions .btn-primary {
    padding: 0.45rem 0.9rem;
    font-size: 0.85rem;
  }

  .hero {
    padding-top: var(--space-2xl);
  }

  .hero-actions .btn {
    flex: 1 1 auto;
    justify-content: center;
  }

  .glass-strip {
    padding: 1rem 1.25rem;
    gap: var(--space-sm) var(--space-lg);
  }

  .card-grid-5,
  .card-grid-3,
  .steps,
  .privacy-grid,
  .showcase-media-pair {
    grid-template-columns: 1fr;
  }

  .card-grid-5 .card:nth-child(5) {
    grid-column: auto;
  }

  .footer-links {
    margin-left: 0;
    width: 100%;
  }
}