/* ── RESET & TOKENS ───────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --_colors---dark:   #1c1c1e;
  --_colors---white:  #ffffff;
  --_colors---7d7d7d: #7d7d7d;
  --_colors---blue:   #4d65ff;

  /* aliases */
  --color-dark:     var(--_colors---dark);
  --color-white:    var(--_colors---white);
  --color-mid:      var(--_colors---7d7d7d);
  --color-mid-inv:  rgba(255,255,255,0.5);
  --color-blue:     var(--_colors---blue);
  --color-bg:       #f0f0f0;
  --color-border:   rgba(0,0,0,0.09);

  --radius: 0.5rem;
  --container: 87.5rem;
  --padding-global: 5%;
}

html { scroll-behavior: smooth; scroll-padding-top: 5rem; }

body {
  background-color: var(--color-bg);
  color: var(--color-dark);
  font-family: Inter, Arial, sans-serif;
  font-size: 1rem;
  font-weight: 400;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ── UTILITY ─────────────────────────────────────────────────────────────── */
.container      { width: var(--container); max-width: 100%; margin: 0 auto; }
.padding-global { padding-left: var(--padding-global); padding-right: var(--padding-global); }
.font-mono      { font-family: 'IBM Plex Mono', monospace; }
.color-mid      { color: var(--color-mid); }
.color-mid-inv  { color: var(--color-mid-inv); }

.spacer-16  { width: 100%; padding-top: 1rem; }
.spacer-24  { width: 100%; padding-top: 1.5rem; }
.spacer-48  { width: 100%; padding-top: 3rem; }
.spacer-fill { flex: 1; }

.section-inner-white {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 3.5rem 2.5rem;
  position: relative;
  overflow: hidden;
}
.section-inner-dark {
  background-color: var(--color-dark);
  color: var(--color-white);
  border-radius: var(--radius);
  padding: 3.5rem 2.5rem;
}

.section-label {
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-mid);
}

/* ── TYPOGRAPHY ──────────────────────────────────────────────────────────── */
.t-heading-display {
  font-family: Inter, Arial, sans-serif;
  font-size: clamp(2.5rem, 6vw, 5rem);
  font-weight: 600;
  line-height: 1.05;
  letter-spacing: -0.03em;
  color: var(--color-white);
}
.t-heading-48 {
  font-size: clamp(1.75rem, 3.5vw, 2.75rem);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
}
.t-paragraph-18 { font-size: 1.125rem; line-height: 1.65; }
.t-paragraph-16 { font-size: 1rem;     line-height: 1.65; }

kbd {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.85em;
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 0.2rem;
  padding: 0.1em 0.45em;
}

/* ── BUTTON ──────────────────────────────────────────────────────────────── */
.c-button {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  border: 1px solid var(--color-dark);
  background-color: var(--color-dark);
  color: var(--color-white);
  letter-spacing: 0em;
  text-transform: uppercase;
  border-radius: var(--radius);
  padding: 0.875rem 1.5rem;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.75rem;
  font-weight: 400;
  text-decoration: none;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color 0.16s, color 0.16s, border-color 0.16s;
}
.c-button:hover {
  background-color: var(--color-white);
  color: var(--color-dark);
  border-color: var(--color-dark);
}

/* Blue primary */
.c-button--blue {
  background-color: var(--color-blue);
  border-color: var(--color-blue);
  color: var(--color-white);
}
.c-button--blue:hover {
  background-color: #3a51e8;
  border-color: #3a51e8;
  color: var(--color-white);
}

/* White (on dark bg) */
.c-button.white {
  border-color: var(--color-white);
  background-color: var(--color-white);
  color: var(--color-dark);
}
.c-button.white:hover {
  background-color: transparent;
  color: var(--color-white);
}

/* Ghost white */
.c-button.outline-white {
  border-color: rgba(255,255,255,0.35);
  background-color: transparent;
  color: rgba(255,255,255,0.75);
}
.c-button.outline-white:hover {
  background-color: rgba(255,255,255,0.08);
  color: var(--color-white);
  border-color: rgba(255,255,255,0.6);
}

/* ── NAV ─────────────────────────────────────────────────────────────────── */
.navbar_component {
  background-color: var(--color-bg);
  padding: 1.125rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--color-border);
}
.navbar_inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.navbar_logo {
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-dark);
  text-decoration: none;
  letter-spacing: -0.02em;
}
.navbar_links {
  display: flex;
  align-items: center;
  gap: 2rem;
}
.navbar_link {
  font-size: 0.8125rem;
  color: var(--color-mid);
  text-decoration: none;
  transition: color 0.15s;
}
.navbar_link:hover { color: var(--color-dark); }

.navbar_mobile-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.navbar_mobile-btn span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--color-dark);
  border-radius: 2px;
}
.navbar_mobile-menu {
  display: none;
  flex-direction: column;
  background: var(--color-bg);
  padding: 1rem var(--padding-global) 1.5rem;
  border-bottom: 1px solid var(--color-border);
}
.navbar_mobile-menu.open { display: flex; }
.navbar_mobile-link {
  font-size: 0.875rem;
  color: var(--color-dark);
  text-decoration: none;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--color-border);
}

/* ── HERO ────────────────────────────────────────────────────────────────── */
.section_hero {
  padding-top: 1.5rem;
  padding-bottom: 1.5rem;
  min-height: calc(100dvh - 3.5rem);
  display: flex;
  flex-direction: column;
}
.section_hero .container {
  flex: 1;
  display: flex;
  flex-direction: column;
}
.hero-wrapper {
  background-color: var(--color-dark);
  border-radius: var(--radius);
  padding: 3.5rem 3rem;
  flex: 1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
  min-height: calc(100dvh - 7rem);
}
.hero-content {
  display: flex;
  flex-direction: column;
  height: 100%;
}
.hero-tag {
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-mid-inv);
}
.hero-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  align-items: center;
}
.hero-footnote {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.3);
  letter-spacing: 0.04em;
}

/* ── App window mock ──────────────────────────────────────────────────────── */
.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}
.app-window {
  background: #28282a;
  border-radius: 0.75rem;
  overflow: hidden;
  width: 100%;
  max-width: 40em;
  border: 1px solid rgba(255,255,255,0.08);
  box-shadow: 0 24px 64px rgba(0,0,0,0.5);
}
.app-window__chrome {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.875rem 1rem;
  background: #222224;
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.chrome-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}
.chrome-dot--close { background: #ff5f57; }
.chrome-dot--min   { background: #febc2e; }
.chrome-dot--max   { background: #28c840; }
.chrome-title {
  font-size: 0.7rem;
  color: rgba(255,255,255,0.35);
  letter-spacing: 0.06em;
  margin-left: auto;
  margin-right: auto;
  padding-right: 3rem; /* optical center */
}
.app-window__body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.app-search {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 0.375rem;
  padding: 0.625rem 0.875rem;
  font-size: 0.875rem;
  color: rgba(255,255,255,0.85);
}
.app-search__icon { color: rgba(255,255,255,0.3); font-size: 1rem; }
.app-search__cursor {
  display: inline-block;
  width: 1px;
  height: 1em;
  background: var(--color-blue);
  animation: blink 1s step-end infinite;
  margin-left: 2px;
}
@keyframes blink { 0%,100% { opacity: 1; } 50% { opacity: 0; } }

.app-result { display: flex; flex-direction: column; gap: 0.5rem; }
.app-result__word {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-white);
  letter-spacing: -0.02em;
}
.app-result__phonetics {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.phonetic-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 0.375rem;
  padding: 0.35rem 0.65rem;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
}
.phonetic-badge:hover {
  background: rgba(77,101,255,0.12);
  border-color: rgba(77,101,255,0.4);
}
.phonetic-badge__label {
  font-size: 0.625rem;
  text-transform: uppercase;
  color: rgba(255,255,255,0.35);
  letter-spacing: 0.06em;
}
.phonetic-badge__ipa {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.6);
}
.phonetic-badge__icon {
  font-size: 0.6rem;
  color: var(--color-blue);
  opacity: 0;
  transition: opacity 0.15s;
}
.phonetic-badge:hover .phonetic-badge__icon {
  opacity: 1;
}
.app-result__divider {
  height: 1px;
  background: rgba(255,255,255,0.08);
  margin: 0.25rem 0;
}
.app-def { display: flex; flex-direction: column; gap: 0.5rem; }
.app-def__meta {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.app-def__pos {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-blue);
  background: rgba(77,101,255,0.12);
  border-radius: 0.25rem;
  padding: 0.15em 0.5em;
}
.app-def__level {
  font-size: 0.65rem;
  letter-spacing: 0.04em;
  color: #ff453a;
  background: rgba(255,69,58,0.12);
  border-radius: 0.25rem;
  padding: 0.15em 0.5em;
}
.app-def__en {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.8);
  line-height: 1.55;
}
.app-def__zh {
  font-size: 0.8125rem;
  color: rgba(255,255,255,0.45);
  line-height: 1.5;
}
.app-def__example {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 0.5rem 0.75rem;
  border-left: 2px solid rgba(255,255,255,0.08);
  margin-top: 0.25rem;
}
.app-def__example-text {
  font-size: 0.8rem;
  color: rgba(255,255,255,0.4);
  font-style: italic;
}
.app-def__example-zh {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.25);
}
.app-shortcut {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 0.75rem;
  border-top: 1px solid rgba(255,255,255,0.06);
  font-size: 0.75rem;
  color: rgba(255,255,255,0.25);
  letter-spacing: 0.04em;
}
.app-shortcut kbd {
  background: rgba(255,255,255,0.06);
  border-color: rgba(255,255,255,0.1);
  color: rgba(255,255,255,0.4);
}

/* ── PROBLEMS ────────────────────────────────────────────────────────────── */
.section_problems { padding-top: 1.5rem; padding-bottom: 0; }
.problems-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}
.problem-card { display: flex; flex-direction: column; }
.problem-num {
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  color: var(--color-mid);
}
.problem-title {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

/* ── TICKER ──────────────────────────────────────────────────────────────── */
.section_ticker { padding-top: 1.5rem; padding-bottom: 0; }
.ticker-wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
  overflow: hidden;
}
.ticker-label h2 { color: var(--color-white); }
.ticker-track-wrapper {
  height: 14rem;
  overflow: hidden;
  mask-image: linear-gradient(to bottom, transparent, black 20%, black 80%, transparent);
  -webkit-mask-image: linear-gradient(to bottom, transparent, black 20%, black 80%, transparent);
  position: relative;
}
.ticker-track {
  list-style: none;
  display: flex;
  flex-direction: column;
  animation: ticker-scroll 8s linear infinite;
}
.ticker-track:hover { animation-play-state: paused; }
@keyframes ticker-scroll {
  0%   { transform: translateY(0); }
  100% { transform: translateY(-50%); }
}
.ticker-item {
  font-size: 1.375rem;
  font-weight: 400;
  color: rgba(255,255,255,0.55);
  padding: 0.875rem 0;
  border-bottom: 1px solid rgba(255,255,255,0.08);
  letter-spacing: -0.01em;
  transition: color 0.2s;
  cursor: default;
  white-space: nowrap;
}
.ticker-item:hover { color: var(--color-white); }

/* ── FEATURES ────────────────────────────────────────────────────────────── */
.section_features { padding-top: 1.5rem; padding-bottom: 0; }

/* Horizontal tabs */
.features-tab-btns {
  display: flex;
  gap: 0.375rem;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0;
}
.features-tab-btn {
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--color-mid);
  font-size: 0.8125rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  padding: 0.75rem 1.125rem;
  cursor: pointer;
  margin-bottom: -1px;
  transition: color 0.15s, border-color 0.15s;
  border-radius: 0;
}
.features-tab-btn:hover { color: var(--color-dark); }
.features-tab-btn.active {
  color: var(--color-dark);
  border-bottom-color: var(--color-dark);
}

.features-tab-panels { }
.features-tab-panel { display: none; }
.features-tab-panel.active { display: block; }
.feature-panel-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
  padding-top: 2.5rem;
}
.feature-title {
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}
.feature-tag {
  display: inline-block;
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-mid);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.3rem 0.7rem;
}

/* Feature mock */
.feature-visual { display: flex; justify-content: flex-end; }
.feature-mock {
  background: var(--color-dark);
  border-radius: var(--radius);
  padding: 1.75rem;
  width: 100%;
  max-width: 22rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.mock-bar {
  font-size: 0.7rem;
  color: rgba(255,255,255,0.3);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.mock-word {
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--color-white);
  letter-spacing: -0.02em;
}
.mock-sep {
  height: 1px;
  background: rgba(255,255,255,0.08);
}
.mock-def {
  font-size: 0.8125rem;
  line-height: 1.6;
  color: rgba(255,255,255,0.65);
}
.mock-phonetics {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}
.mock-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.7rem;
  color: rgba(255,255,255,0.55);
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 0.3rem;
  padding: 0.25rem 0.55rem;
}
.mock-badge--highlight {
  background: rgba(77,101,255,0.12);
  border-color: rgba(77,101,255,0.35);
}
.mock-badge__label {
  font-size: 0.6rem;
  color: rgba(255,255,255,0.3);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.mock-badge__play {
  font-size: 0.55rem;
  color: var(--color-blue);
}
.mock-tags {
  display: flex;
  gap: 0.3rem;
}
.mock-pos {
  font-size: 0.6rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-blue);
  background: rgba(77,101,255,0.12);
  border-radius: 0.2rem;
  padding: 0.15em 0.45em;
}
.mock-level {
  font-size: 0.6rem;
  letter-spacing: 0.04em;
  color: #ff453a;
  background: rgba(255,69,58,0.12);
  border-radius: 0.2rem;
  padding: 0.15em 0.45em;
}
.mock-example {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  padding: 0.4rem 0.6rem;
  border-left: 2px solid rgba(255,255,255,0.08);
  margin-top: 0.25rem;
}
.mock-example__text {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.35);
  font-style: italic;
}
.mock-example__zh {
  font-size: 0.7rem;
  color: rgba(255,255,255,0.2);
}
.mock-play {
  margin-top: 0.25rem;
  font-size: 0.7rem;
  color: var(--color-blue);
  background: rgba(77,101,255,0.12);
  border: 1px solid rgba(77,101,255,0.3);
  border-radius: 0.3rem;
  padding: 0.4em 0.8em;
  cursor: pointer;
  letter-spacing: 0.04em;
  align-self: flex-start;
}
.mock-setting {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
  color: rgba(255,255,255,0.75);
}
.mock-setting__value {
  color: var(--color-blue);
}

/* ── FAQ ─────────────────────────────────────────────────────────────────── */
.section_faq { padding-top: 1.5rem; padding-bottom: 0; }
.faq-layout {
  display: grid;
  grid-template-columns: 1fr 1.8fr;
  gap: 5rem;
  align-items: start;
}
.faq-contact-link {
  font-size: 0.8125rem;
  color: var(--color-dark);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.faq-item {
  border-bottom: 1px solid var(--color-border);
}
.faq-item:first-child { border-top: 1px solid var(--color-border); }
.faq-q {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 0;
  cursor: pointer;
  font-size: 0.875rem;
  letter-spacing: 0.01em;
  list-style: none;
  color: var(--color-dark);
  user-select: none;
}
.faq-q::-webkit-details-marker { display: none; }
.faq-q::after {
  content: '+';
  font-size: 1.25rem;
  font-weight: 300;
  flex-shrink: 0;
  color: var(--color-mid);
  transition: transform 0.2s;
  font-family: Inter, sans-serif;
}
.faq-item[open] .faq-q::after { transform: rotate(45deg); }
.faq-a {
  font-size: 0.9375rem;
  line-height: 1.7;
  padding-bottom: 1.25rem;
  color: var(--color-mid);
}

/* ── CTA ─────────────────────────────────────────────────────────────────── */
.section_cta { padding-top: 1.5rem; padding-bottom: 0; }
.cta-inner { max-width: 48rem; }
.cta-form-inner {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  align-items: center;
}
.form-input {
  border: 1px solid rgba(255,255,255,0.15);
  background: rgba(255,255,255,0.07);
  color: var(--color-white);
  border-radius: var(--radius);
  height: 3rem;
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  font-family: 'IBM Plex Mono', monospace;
  min-width: 18rem;
  outline: none;
  transition: border-color 0.15s, background 0.15s;
}
.form-input::placeholder { color: rgba(255,255,255,0.3); }
.form-input:focus {
  border-color: rgba(255,255,255,0.4);
  background: rgba(255,255,255,0.1);
}
.form-note {
  font-size: 0.75rem;
  letter-spacing: 0.02em;
}
.form-success {
  display: none;
  padding: 2rem 0;
}
.form-success.show { display: block; }
.success-mark {
  font-size: 1.75rem;
  color: var(--color-white);
  opacity: 0.6;
}

/* ── FOOTER ──────────────────────────────────────────────────────────────── */
.footer {
  padding-top: 3rem;
  padding-bottom: 3rem;
  margin-top: 1.5rem;
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}
.footer-brand {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-dark);
}
.footer-links { display: flex; gap: 1.5rem; }
.footer-link {
  font-size: 0.75rem;
  color: var(--color-mid);
  text-decoration: none;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  transition: color 0.15s;
}
.footer-link:hover { color: var(--color-dark); }
.footer-copy {
  font-size: 0.75rem;
  color: var(--color-mid);
}

/* ── SCROLL REVEAL ───────────────────────────────────────────────────────── */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.in {
  opacity: 1;
  transform: none;
}

/* ── RESPONSIVE ──────────────────────────────────────────────────────────── */
@media (max-width: 1024px) {
  .hero-wrapper { grid-template-columns: 1fr; }
  .hero-visual { display: none; }
  .hero-content { height: auto; }

  .ticker-wrapper { grid-template-columns: 1fr; }
  .ticker-track-wrapper { height: 8rem; }

  .problems-grid { grid-template-columns: 1fr 1fr; }
  .feature-panel-inner { grid-template-columns: 1fr; }
  .feature-visual { display: none; }
  .faq-layout { grid-template-columns: 1fr; gap: 2.5rem; }
}

@media (max-width: 768px) {
  :root { --padding-global: 1.25rem; }

  .navbar_links { display: none; }
  .navbar_mobile-btn { display: flex; }

  .hero-wrapper { padding: 2rem 1.5rem; min-height: 80dvh; }
  .t-heading-display { font-size: 2.5rem; }
  .t-heading-48 { font-size: 1.75rem; }

  .problems-grid { grid-template-columns: 1fr; }
  .features-tab-btns { gap: 0; overflow-x: auto; }
  .features-tab-btn { padding: 0.75rem 0.875rem; font-size: 0.75rem; flex-shrink: 0; }

  .section-inner-white,
  .section-inner-dark { padding: 2rem 1.5rem; }

  .cta-form-inner { flex-direction: column; align-items: stretch; }
  .form-input { min-width: unset; }

  .footer-inner { flex-direction: column; align-items: flex-start; gap: 1rem; }
}