/* =========================================
   LAYOUT — Grid & Bento System
   ========================================= */

/* --- 12-Column Grid --- */
.grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--grid-gap);
}

/* --- Section Wrapper --- */
.section-inner {
  display: grid;
  grid-template-rows: auto 1fr;
}

/* --- Bento Grid Items --- */
.bento-item {
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-border);
  padding: var(--space-8);
  position: relative;
  overflow: hidden;
  transition:
    transform var(--duration-normal) var(--ease-out-quart),
    box-shadow var(--duration-normal) var(--ease-out-quart),
    border-color var(--duration-normal) var(--ease-out-quart);
}

.bento-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
  border-color: var(--color-accent);
  z-index: 1;
}

/* --- Bento Sizes --- */
.bento-large  { grid-column: span 8; }
.bento-medium { grid-column: span 6; }
.bento-small  { grid-column: span 4; }
.bento-half   { grid-column: span 5; }
.bento-third  { grid-column: span 3; }
.bento-full   { grid-column: span 12; }

/* --- Two-Column Split --- */
.split-60-40 {
  display: grid;
  grid-template-columns: 3fr 2fr;
  gap: clamp(1.5rem, 4vw, 3.5rem);
  align-items: center;
}

.split-50-50 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--grid-gap);
}

.split-40-60 {
  display: grid;
  grid-template-columns: 2fr 3fr;
  gap: var(--grid-gap);
  align-items: start;
}

/* --- Flex Utilities --- */
.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.items-center {
  align-items: center;
}

.items-start {
  align-items: flex-start;
}

.justify-between {
  justify-content: space-between;
}

.justify-center {
  justify-content: center;
}

.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

/* --- Sticky Header --- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-height);
  display: flex;
  align-items: center;
  background: rgba(18, 18, 18, 0.88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-border);
  transition: background var(--duration-normal) var(--ease-out-quart);
}

.header.is-scrolled {
  background: rgba(12, 12, 12, 0.96);
}

.header__inner {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  column-gap: var(--space-5);
}

.header__logo {
  grid-column: 1;
  justify-self: start;
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-primary);
  white-space: nowrap;
  line-height: 1;
}

.header__logo::after {
  content: '.';
  color: var(--color-accent);
}

html[lang="zh"] .header__logo {
  font-size: 1.05rem;
  letter-spacing: 0.16em;
  text-transform: none;
}

.header__actions {
  grid-column: 3;
  justify-self: end;
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* --- Main offset for fixed header --- */
main {
  padding-top: var(--header-height);
}

/* --- Responsive --- */
@media (max-width: 1024px) {
  .bento-large  { grid-column: span 12; }
  .bento-medium { grid-column: span 6; }
  .bento-small  { grid-column: span 6; }
  .bento-half   { grid-column: span 6; }
  .bento-third  { grid-column: span 4; }
  .split-60-40  { grid-template-columns: 1fr; }
  .split-40-60  { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .bento-large,
  .bento-medium,
  .bento-small,
  .bento-half,
  .bento-third,
  .bento-full   { grid-column: span 12; }

  .split-50-50 { grid-template-columns: 1fr; }
  .grid { grid-template-columns: 1fr; }
}