/* ============================================
   Digital PB School 2.0 - Common Styles
   ============================================ */

/* ── Layout ── */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--content-padding);
}

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

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

.section {
  padding: var(--space-section) 0;
  position: relative;
}

.section--dark {
  background-color: var(--color-primary);
  color: var(--color-gray-200);
}

.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark h4 {
  color: var(--color-white);
}

.section--light {
  background-color: var(--bg-section-light);
}

.section--accent-line::before {
  content: '';
  display: block;
  width: 48px;
  height: 2px;
  background-color: var(--color-accent);
  margin-bottom: var(--space-lg);
}

/* ── Header / Navigation ── */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-header);
  height: var(--header-height);
  display: flex;
  align-items: center;
  transition: all var(--duration-normal) var(--ease-default);
}

.header--transparent {
  background-color: transparent;
}

.header--scrolled {
  height: var(--header-height-scroll);
  background-color: rgba(255, 255, 255, 0.97);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.06);
}

.header--scrolled .header__logo-text {
  color: var(--color-primary);
}

.header--scrolled .nav__link {
  color: var(--color-gray-700);
}

.header--scrolled .nav__link:hover,
.header--scrolled .nav__link--active {
  color: var(--color-primary);
}

.header--dark-page.header--scrolled {
  background-color: rgba(27, 31, 59, 0.97);
}

.header--dark-page.header--scrolled .header__logo-text {
  color: var(--color-white);
}

.header--dark-page.header--scrolled .nav__link {
  color: var(--color-gray-300);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: 0 var(--content-padding);
}

.header__logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  flex-shrink: 0;
}

.header__logo-icon {
  width: 36px;
  height: 36px;
}

.header__logo-text {
  font-family: var(--font-body);
  font-size: 1.15rem;
  font-weight: var(--fw-bold);
  color: var(--color-white);
  letter-spacing: var(--ls-tight);
  transition: color var(--duration-normal) var(--ease-default);
}

.header__logo-text span {
  color: var(--color-accent);
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--space-2xl);
}

.nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.nav__link {
  font-size: var(--fs-body-sm);
  font-weight: var(--fw-medium);
  color: rgba(255, 255, 255, 0.85);
  letter-spacing: var(--ls-wide);
  position: relative;
  padding: var(--space-xs) 0;
  transition: color var(--duration-fast) var(--ease-default);
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1.5px;
  background-color: var(--color-accent);
  transition: width var(--duration-normal) var(--ease-out);
}

.nav__link:hover,
.nav__link--active {
  color: var(--color-white);
}

.nav__link:hover::after,
.nav__link--active::after {
  width: 100%;
}

.nav__cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
}

/* Mobile Menu Toggle */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 28px;
  height: 28px;
  cursor: pointer;
  z-index: var(--z-modal);
}

.nav-toggle__bar {
  display: block;
  width: 100%;
  height: 1.5px;
  background-color: var(--color-white);
  transition: all var(--duration-normal) var(--ease-default);
  transform-origin: center;
}

.header--scrolled .nav-toggle__bar {
  background-color: var(--color-primary);
}

.nav-toggle--active .nav-toggle__bar:nth-child(1) {
  transform: translateY(6.5px) rotate(45deg);
}

.nav-toggle--active .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle--active .nav-toggle__bar:nth-child(3) {
  transform: translateY(-6.5px) rotate(-45deg);
}

/* ── Section Titles ── */
.section-label {
  font-family: var(--font-en-display);
  font-size: var(--fs-caption);
  font-weight: var(--fw-regular);
  letter-spacing: var(--ls-widest);
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.section-label::before {
  content: '';
  display: inline-block;
  width: 32px;
  height: 1px;
  background-color: var(--color-accent);
}

.section-title {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  font-weight: var(--fw-bold);
  line-height: var(--lh-tight);
  color: var(--color-black);
  margin-bottom: var(--space-lg);
  letter-spacing: var(--ls-tight);
}

.section-title--light {
  color: var(--color-white);
}

.section-title--center {
  text-align: center;
}

.section-subtitle {
  font-size: var(--fs-body-lg);
  font-weight: var(--fw-regular);
  color: var(--color-gray-500);
  line-height: var(--lh-relaxed);
  max-width: 640px;
}

.section-subtitle--center {
  text-align: center;
  margin-left: auto;
  margin-right: auto;
}

.section-header {
  margin-bottom: var(--space-3xl);
}

.section-header--center {
  text-align: center;
}

.section-header--center .section-label {
  justify-content: center;
}

.section-header--center .section-label::before {
  display: none;
}

/* ── Divider ── */
.divider {
  width: 48px;
  height: 1.5px;
  background-color: var(--color-accent);
  margin: var(--space-xl) 0;
}

.divider--center {
  margin-left: auto;
  margin-right: auto;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  font-family: var(--font-body);
  font-size: var(--fs-body-sm);
  font-weight: var(--fw-semibold);
  letter-spacing: var(--ls-wide);
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  transition: all var(--duration-normal) var(--ease-default);
  position: relative;
  overflow: hidden;
  white-space: nowrap;
  cursor: pointer;
}

.btn--primary {
  background-color: var(--color-accent);
  color: var(--color-white);
}

.btn--primary:hover {
  background-color: var(--color-accent-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn--outline {
  border: 1px solid var(--color-accent);
  color: var(--color-accent);
  background-color: transparent;
}

.btn--outline:hover {
  background-color: var(--color-accent);
  color: var(--color-white);
}

.btn--outline-white {
  border: 1px solid rgba(255, 255, 255, 0.4);
  color: var(--color-white);
  background-color: transparent;
}

.btn--outline-white:hover {
  border-color: var(--color-white);
  background-color: rgba(255, 255, 255, 0.1);
}

.btn--dark {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.btn--dark:hover {
  background-color: var(--color-primary-light);
  transform: translateY(-1px);
}

.btn--ghost {
  color: var(--color-gray-600);
  padding: 10px 16px;
}

.btn--ghost:hover {
  color: var(--color-accent);
}

.btn--lg {
  padding: 18px 44px;
  font-size: var(--fs-body);
}

.btn--sm {
  padding: 10px 22px;
  font-size: var(--fs-caption);
}

.btn__arrow {
  display: inline-block;
  transition: transform var(--duration-fast) var(--ease-default);
}

.btn:hover .btn__arrow {
  transform: translateX(3px);
}

/* ── Cards ── */
.card {
  background-color: var(--bg-card);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--duration-normal) var(--ease-default);
}

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

.card--bordered {
  border: 1px solid var(--color-gray-200);
}

.card--bordered:hover {
  border-color: var(--color-accent);
}

.card__image {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.card__body {
  padding: var(--space-xl);
}

.card__tag {
  font-size: var(--fs-label);
  font-weight: var(--fw-semibold);
  letter-spacing: var(--ls-wider);
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-sm);
}

.card__title {
  font-family: var(--font-display);
  font-size: var(--fs-h4);
  font-weight: var(--fw-bold);
  color: var(--color-black);
  margin-bottom: var(--space-sm);
  line-height: var(--lh-tight);
}

.card__desc {
  font-size: var(--fs-body-sm);
  color: var(--color-gray-500);
  line-height: var(--lh-relaxed);
}

/* Icon Card - 아이콘 + 텍스트 카드 */
.icon-card {
  padding: var(--space-2xl);
  text-align: left;
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-md);
  background-color: var(--color-white);
  transition: all var(--duration-normal) var(--ease-default);
}

.icon-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-3px);
}

.icon-card__icon {
  width: 48px;
  height: 48px;
  margin-bottom: var(--space-lg);
  color: var(--color-accent);
}

.icon-card__number {
  font-family: var(--font-en-display);
  font-size: var(--fs-h1);
  font-weight: var(--fw-light);
  color: var(--color-accent);
  opacity: 0.35;
  margin-bottom: var(--space-md);
  line-height: 1;
}

.icon-card__title {
  font-family: var(--font-display);
  font-size: var(--fs-h4);
  font-weight: var(--fw-bold);
  color: var(--color-black);
  margin-bottom: var(--space-sm);
}

.icon-card__desc {
  font-size: var(--fs-body-sm);
  color: var(--color-gray-500);
  line-height: var(--lh-relaxed);
}

/* ── Grid Layouts ── */
.grid {
  display: grid;
  gap: var(--space-xl);
}

.grid--2 {
  grid-template-columns: repeat(2, 1fr);
}

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

.grid--4 {
  grid-template-columns: repeat(4, 1fr);
}

.grid--2-1 {
  grid-template-columns: 2fr 1fr;
}

.grid--1-2 {
  grid-template-columns: 1fr 2fr;
}

/* ── Feature Row (Image + Text Side-by-Side) ── */
.feature-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4xl);
  align-items: center;
}

.feature-row--reverse {
  direction: rtl;
}

.feature-row--reverse > * {
  direction: ltr;
}

.feature-row__media {
  position: relative;
  border-radius: var(--radius-md);
  overflow: hidden;
}

.feature-row__media img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.feature-row__media::after {
  content: '';
  position: absolute;
  inset: 0;
  border: 1px solid rgba(184, 148, 95, 0.2);
  border-radius: var(--radius-md);
  pointer-events: none;
}

.feature-row__content {
  padding: var(--space-xl) 0;
}

/* ── Stats / Numbers ── */
.stat {
  text-align: center;
  padding: var(--space-xl);
}

.stat__number {
  font-family: var(--font-en-display);
  font-size: var(--fs-hero);
  font-weight: var(--fw-light);
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: var(--space-xs);
}

.stat__label {
  font-size: var(--fs-body-sm);
  color: var(--color-gray-400);
  letter-spacing: var(--ls-wide);
}

/* ── Footer ── */
.footer {
  background-color: var(--color-primary-dark);
  color: var(--color-gray-400);
  padding: var(--space-4xl) 0 var(--space-2xl);
}

.footer__inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-3xl);
}

.footer__brand {
  padding-right: var(--space-2xl);
}

.footer__logo {
  font-family: var(--font-body);
  font-size: 1.15rem;
  font-weight: var(--fw-bold);
  color: var(--color-white);
  margin-bottom: var(--space-lg);
  display: inline-block;
}

.footer__logo span {
  color: var(--color-accent);
}

.footer__desc {
  font-size: var(--fs-body-sm);
  line-height: var(--lh-relaxed);
  color: var(--color-gray-400);
  margin-bottom: var(--space-lg);
}

.footer__nav-title {
  font-size: var(--fs-body-sm);
  font-weight: var(--fw-semibold);
  color: var(--color-white);
  letter-spacing: var(--ls-wide);
  margin-bottom: var(--space-lg);
}

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

.footer__nav-link {
  font-size: var(--fs-body-sm);
  color: var(--color-gray-400);
  transition: color var(--duration-fast) var(--ease-default);
}

.footer__nav-link:hover {
  color: var(--color-accent-light);
}

.footer__bottom {
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer__copyright {
  font-size: var(--fs-caption);
  color: var(--color-gray-500);
}

.footer__legal {
  display: flex;
  gap: var(--space-lg);
}

.footer__legal a {
  font-size: var(--fs-caption);
  color: var(--color-gray-500);
}

.footer__legal a:hover {
  color: var(--color-accent-light);
}

/* ── Back to Top ── */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  background-color: var(--color-primary);
  color: var(--color-white);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: var(--z-sticky);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all var(--duration-normal) var(--ease-default);
  box-shadow: var(--shadow-md);
  cursor: pointer;
}

.back-to-top--visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background-color: var(--color-accent);
  transform: translateY(-2px);
}

.back-to-top svg {
  width: 18px;
  height: 18px;
}

/* ── Loading / Preloader ── */
.preloader {
  position: fixed;
  inset: 0;
  background-color: var(--color-primary-dark);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity var(--duration-slow) var(--ease-default);
}

.preloader--hidden {
  opacity: 0;
  pointer-events: none;
}

.preloader__spinner {
  width: 40px;
  height: 40px;
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ── Utility Classes ── */
.text-accent { color: var(--color-accent); }
.text-white { color: var(--color-white); }
.text-muted { color: var(--color-gray-400); }
.text-center { text-align: center; }
.text-left { text-align: left; }

.mt-0 { margin-top: 0; }
.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mt-2xl { margin-top: var(--space-2xl); }
.mt-3xl { margin-top: var(--space-3xl); }

.mb-0 { margin-bottom: 0; }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }
.mb-2xl { margin-bottom: var(--space-2xl); }

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