/* ============================================================
   BIDEO Intro Page — YouTube Creators 스타일 재현
   ============================================================ */

/* ----- Variables ----- */
:root,
[data-theme="light"] {
  --color-bg: #ffffff;
  --color-bg-alt: #f8f8f8;
  --color-surface: #ffffff;
  --color-text: #0d0d0d;
  --color-text-secondary: #606060;
  --color-text-muted: #909090;
  --color-link: #065fd4;
  --color-link-hover: #0249a8;
  --color-highlight-bg: #1a73e8;
  --color-highlight-text: #ffffff;
  --color-border: rgba(0, 0, 0, 0.1);
  --color-card-hover: rgba(0, 0, 0, 0.04);
  --color-footer-bg: #282828;
  --color-footer-text: #aaaaaa;
  --color-footer-heading: #ffffff;
  --header-height: 64px;
  --max-width: 1280px;
  --font-family: 'Roboto', sans-serif;
}

[data-theme="dark"] {
  --color-bg: #0f0f0f;
  --color-bg-alt: #1a1a1a;
  --color-surface: #1a1a1a;
  --color-text: #f1f1f1;
  --color-text-secondary: #aaaaaa;
  --color-text-muted: #717171;
  --color-link: #3ea6ff;
  --color-link-hover: #6dbfff;
  --color-highlight-bg: #1a73e8;
  --color-highlight-text: #ffffff;
  --color-border: rgba(255, 255, 255, 0.1);
  --color-card-hover: rgba(255, 255, 255, 0.06);
  --color-footer-bg: #0f0f0f;
  --color-footer-text: #717171;
  --color-footer-heading: #f1f1f1;
}

/* ----- Reset ----- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: var(--header-height); }
body {
  font-family: var(--font-family);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
img { max-width: 100%; height: auto; display: block; }
button { cursor: pointer; border: none; background: none; font: inherit; color: inherit; }

/* ----- Grid System (12-column) ----- */
.grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 24px;
  max-width: var(--max-width);
  margin: 0 auto;
}
.grid__cell--4  { grid-column: span 4; }
.grid__cell--5  { grid-column: span 5; }
.grid__cell--6  { grid-column: span 6; }
.grid__cell--12 { grid-column: span 12; }
.grid__cell--offset5-7 { grid-column: 6 / span 7; }

/* ============================================================
   Header (fixed, 64px)
   ============================================================ */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-height);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
}
.site-header__row {
  max-width: var(--max-width);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  padding: 0 24px;
}
.site-header__left {
  display: flex;
  align-items: center;
  gap: 16px;
  flex: 1;
  min-width: 0;
}
.site-header__right {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

/* Logo */
.site-header__logo-wrap {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}
.site-header__logo {
  height: 24px;
  width: auto;
}

/* Skip link */
.site-header__skip {
  position: absolute;
  left: -9999px;
  opacity: 0;
}
.site-header__skip:focus {
  position: static;
  opacity: 1;
  padding: 4px 8px;
  font-size: 0.85rem;
}

/* Main nav */
.site-header__nav-wrapper {
  display: flex;
  align-items: center;
  margin-left: 8px;
}
.site-header__nav-items {
  display: flex;
  align-items: center;
  gap: 4px;
}
.site-header__nav-item {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 8px 12px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  border-radius: 8px;
  transition: background 0.15s, color 0.15s;
  white-space: nowrap;
}
.site-header__nav-item:hover {
  background: var(--color-card-hover);
  color: var(--color-text);
}
.site-header__nav-item.is-active {
  color: var(--color-text);
  font-weight: 600;
}

/* Dropdown */
.site-header__nav-dropdown {
  position: relative;
}
.site-header__nav-item--has-sub svg {
  transition: transform 0.2s;
}
.site-header__nav-item--has-sub[aria-expanded="true"] svg {
  transform: rotate(180deg);
}
.site-header__subnav {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 8px 0;
  min-width: 200px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.12);
  z-index: 100;
}
.site-header__subnav[hidden] { display: none; }
.site-header__subnav-item {
  display: block;
  padding: 10px 20px;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  transition: background 0.15s, color 0.15s;
}
.site-header__subnav-item:hover {
  background: var(--color-card-hover);
  color: var(--color-text);
}

/* Auth button */
.site-header__auth-btn {
  padding: 8px 20px;
  border-radius: 999px;
  background: #6800EA;
  color: #fff;
  font-size: 0.85rem;
  font-weight: 600;
  white-space: nowrap;
  transition: background 0.2s;
}
.site-header__auth-btn:hover { background: #5600c4; }

/* Search */
.site-header__search {
  position: relative;
}
.site-header__search-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  color: var(--color-text-secondary);
  transition: background 0.15s;
}
.site-header__search-toggle:hover {
  background: var(--color-card-hover);
}
.site-header__search-inner {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 8px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.12);
  z-index: 100;
}
.site-header__search-inner[hidden] { display: none; }
.site-header__search-input {
  width: min(280px, calc(100vw - 80px));
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: inherit;
  font-size: 0.875rem;
  outline: none;
}
.site-header__search-input:focus {
  border-color: var(--color-link);
}

/* Mobile menu button */
.site-header__menu-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
}
.site-header__menu-icon {
  display: flex;
  flex-direction: column;
  gap: 5px;
  width: 20px;
}
.site-header__menu-icon span,
.site-header__menu-icon::before,
.site-header__menu-icon::after {
  content: '';
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-text);
  border-radius: 1px;
  transition: transform 0.25s, opacity 0.25s;
}
/* Hamburger open state */
.site-header__menu-btn[aria-expanded="true"] .site-header__menu-icon::before {
  transform: translateY(7px) rotate(45deg);
}
.site-header__menu-btn[aria-expanded="true"] .site-header__menu-icon span {
  opacity: 0;
}
.site-header__menu-btn[aria-expanded="true"] .site-header__menu-icon::after {
  transform: translateY(-7px) rotate(-45deg);
}

/* ============================================================
   Main
   ============================================================ */
.site-main {
  padding-top: var(--header-height);
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  padding: 80px 24px 60px;
}
.hero .grid {
  align-items: center;
}
.hero__text-col {
  display: flex;
  align-items: center;
}
.hero__heading {
  font-size: clamp(2rem, 4vw, 3.5rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}
.hero__desc {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  max-width: 420px;
}
.hero__video-col {
  display: flex;
  align-items: center;
}
.hero__video-container {
  position: relative;
  width: 100%;
  border-radius: 16px;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: #000;
}
.hero__video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.hero__mute-btn {
  position: absolute;
  bottom: 16px;
  right: 16px;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.6);
  border-radius: 50%;
  color: #fff;
  transition: background 0.2s;
}
.hero__mute-btn:hover { background: rgba(0, 0, 0, 0.8); }
.hero__mute-icon { width: 20px; height: 20px; fill: currentColor; }

/* ============================================================
   Highlight (blue card)
   ============================================================ */
.highlight {
  padding: 0 24px;
  margin-bottom: 64px;
}
.highlight--blue .grid {
  background: var(--color-highlight-bg);
  border-radius: 16px;
  padding: 40px;
  align-items: center;
  color: var(--color-highlight-text);
}
.highlight__image-wrap {
  display: block;
  border-radius: 12px;
  overflow: hidden;
}
.highlight__image-wrap img {
  width: 100%;
  display: block;
}
.highlight__content {
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.highlight__top-line {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  opacity: 0.85;
  margin-bottom: 12px;
}
.highlight__heading {
  font-size: clamp(1.25rem, 2.5vw, 2rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 16px;
}
.highlight__desc {
  font-size: 0.95rem;
  opacity: 0.9;
  line-height: 1.7;
  margin-bottom: 24px;
}
.highlight .arrow-link {
  color: var(--color-highlight-text);
}

/* ============================================================
   Arrow Link (reusable)
   ============================================================ */
.arrow-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-link);
  transition: gap 0.2s;
}
.arrow-link:hover { gap: 10px; }
.arrow-link svg { fill: currentColor; flex-shrink: 0; }

/* ============================================================
   Related (6 cards — 2-column grid)
   ============================================================ */
.related {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px 80px;
}
.related__heading {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  margin-bottom: 32px;
}
.related__grid {
  gap: 24px;
}
.related__item {
  display: flex;
  flex-direction: column;
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  transition: box-shadow 0.25s, transform 0.25s;
  height: 100%;
}
.related__item:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  transform: translateY(-2px);
}
.related__media {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--color-bg-alt);
}
.related__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.related__text {
  padding: 24px;
  flex: 1;
  display: flex;
  flex-direction: column;
}
.related__title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}
.related__desc {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
  line-height: 1.5;
  flex: 1;
}
.related__text .arrow-link {
  margin-top: auto;
}

/* ============================================================
   FAQ — Tab-based (numbered tabs left, content right)
   ============================================================ */
.faq-section {
  background: var(--color-bg-alt);
  padding: 80px 24px;
}
.faq-tabular {
  max-width: var(--max-width);
  margin: 0 auto;
}
.faq-tabular__heading {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  margin-bottom: 12px;
}
.faq-tabular__description {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  max-width: 700px;
  margin-bottom: 40px;
}
.faq-tabular__body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}

/* Tabs (left column) */
.tablist {
  display: flex;
  flex-direction: column;
}
.tablist__tab {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 20px 16px;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
  transition: background 0.15s;
  cursor: pointer;
}
.tablist__tab:first-child {
  border-top: 1px solid var(--color-border);
}
.tablist__tab:hover {
  background: var(--color-card-hover);
}
.tablist__tab--active {
  background: var(--color-card-hover);
}
.tablist__number {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text-muted);
  flex-shrink: 0;
  min-width: 36px;
}
.tablist__tab--active .tablist__number {
  color: var(--color-link);
}
.tablist__title {
  font-size: 0.95rem;
  font-weight: 500;
  line-height: 1.4;
}

/* Panels (right column) */
.tabpanel-group {
  padding-top: 20px;
}
.tabpanel {
  display: none;
}
.tabpanel--active {
  display: block;
}
.tabpanel h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
}
.tabpanel p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 16px;
}
.tabpanel p:last-child { margin-bottom: 0; }

/* More link */
.faq-tabular__more {
  margin-top: 32px;
}

/* ============================================================
   Resources (3-column)
   ============================================================ */
.resources {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 80px 24px;
}
.resources__heading {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  margin-bottom: 40px;
}
.resources__icon-wrap {
  margin-bottom: 16px;
}
.resources__icon-wrap img {
  width: 48px;
  height: 48px;
  border-radius: 8px;
}
.resources__title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
}
.resources__desc {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
}
.resources__links {
  font-size: 0.875rem;
}
.resources__links hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 16px 0;
}
.resources__links p {
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  line-height: 1.5;
  margin-bottom: 6px;
}
.resources__links .arrow-link {
  font-size: 0.875rem;
  margin-bottom: 4px;
}

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  background: var(--color-footer-bg);
  color: var(--color-footer-text);
}
.site-footer__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 24px;
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 48px;
}

/* Social */
.site-footer__social-headline {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-footer-heading);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 20px;
}
.site-footer__social-links {
  display: flex;
  gap: 20px;
}
.site-footer__social-links a {
  color: var(--color-footer-text);
  transition: color 0.2s;
}
.site-footer__social-links a:hover { color: #fff; }
.site-footer__social-links svg { display: block; }

/* Link columns */
.site-footer__links {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 24px;
}
.site-footer__col h4 {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-footer-heading);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 16px;
}
.site-footer__col a {
  display: block;
  font-size: 0.85rem;
  color: var(--color-footer-text);
  padding: 3px 0;
  transition: color 0.2s;
}
.site-footer__col a:hover { color: #fff; }

/* Bottom bar */
.site-footer__bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}
.site-footer__bottom-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.site-footer__policies {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}
.site-footer__policies a {
  font-size: 0.8rem;
  color: var(--color-footer-text);
  transition: color 0.2s;
}
.site-footer__policies a:hover { color: #fff; }
.site-footer__bottom-right {
  display: flex;
  align-items: center;
  gap: 16px;
}
.site-footer__logo {
  height: 18px;
  width: auto;
}
.site-footer__bottom-right a {
  font-size: 0.8rem;
  color: var(--color-footer-text);
  transition: color 0.2s;
}
.site-footer__bottom-right a:hover { color: #fff; }

/* ============================================================
   Scroll Animation
   ============================================================ */
.scroll-fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.scroll-fade-up.show {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 1024px) {
  .hero .grid {
    grid-template-columns: 1fr;
  }
  .hero .grid__cell--4,
  .hero .grid__cell--offset5-7 {
    grid-column: span 12;
  }
  .highlight--blue .grid {
    grid-template-columns: 1fr;
  }
  .highlight .grid__cell--5 {
    grid-column: span 12;
  }
  .faq-tabular__body {
    grid-template-columns: 1fr;
  }
  .site-footer__inner {
    grid-template-columns: 1fr;
    gap: 32px;
  }
  .site-footer__links {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 768px) {
  /* Header mobile */
  .site-header__nav-wrapper {
    display: none;
    position: fixed;
    top: var(--header-height);
    left: 0; right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 16px 24px 24px;
    z-index: 999;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  }
  .site-header__nav-wrapper.is-open {
    display: block;
  }
  .site-header__nav-items {
    flex-direction: column;
    gap: 0;
  }
  .site-header__nav-item {
    width: 100%;
    padding: 12px 0;
  }
  .site-header__subnav {
    position: static;
    box-shadow: none;
    border: none;
    padding: 0 0 0 16px;
  }
  .site-header__menu-btn {
    display: flex;
  }

  /* Grid collapses */
  .grid { grid-template-columns: 1fr; }
  .grid__cell--4,
  .grid__cell--5,
  .grid__cell--6,
  .grid__cell--12,
  .grid__cell--md-12,
  .grid__cell--offset5-7 {
    grid-column: span 1;
  }

  /* Hero */
  .hero { padding: 40px 16px 40px; }
  .hero__heading { font-size: 2rem; }

  /* Highlight */
  .highlight { padding: 0 16px; }
  .highlight--blue .grid { padding: 24px; }

  /* Related */
  .related { padding: 0 16px 48px; }
  .related__grid { gap: 16px; }

  /* FAQ */
  .faq-section { padding: 48px 16px; }
  .faq-tabular__body { gap: 24px; }

  /* Resources */
  .resources { padding: 48px 16px; }

  /* Footer */
  .site-footer__inner { padding: 32px 16px; }
  .site-footer__links {
    grid-template-columns: repeat(2, 1fr);
  }
  .site-footer__bottom-inner {
    flex-direction: column;
    gap: 12px;
    text-align: center;
    padding: 16px;
  }
  .site-footer__policies { justify-content: center; }
}

@media (max-width: 480px) {
  .hero { padding: 24px 12px; }
  .hero__heading { font-size: 1.6rem; }
  .hero__desc { font-size: 0.95rem; }

  .highlight--blue .grid { padding: 16px; }

  .related__text { padding: 16px; }
  .related__title { font-size: 0.9rem; }

  .faq-section { padding: 32px 12px; }
  .tablist__tab { padding: 14px 12px; gap: 12px; }
  .tablist__number { font-size: 1.2rem; }

  .resources { padding: 32px 12px; }

  .site-footer__links { grid-template-columns: 1fr; }
  .site-footer__inner { padding: 24px 12px; }
  .site-footer__bottom-inner { padding: 12px; }
}