/* ============================================================================
   YUEQIAN LABS DESIGN SYSTEM
   月前实验室 设计系统
   ============================================================================
   Strict token-based design system. No ad-hoc values.
   All spacing, typography, and color must reference tokens.
   ============================================================================ */

/* --- Reset ---------------------------------------------------------------- */

*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  font-feature-settings: 'tnum' 1;
}

body {
  font-family: var(--font-en);
  font-size: 1rem;
  font-weight: 400;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  overflow-x: hidden;
  min-height: 100vh;
}

img, picture, video, canvas, svg {
  display: block;
  max-width: 100%;
}

input, button, textarea, select {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

a {
  color: inherit;
  text-decoration: none;
}

ul, ol {
  list-style: none;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 500;
  line-height: 1.05;
  letter-spacing: -0.01em;
}

table {
  border-collapse: collapse;
  width: 100%;
}

/* --- Custom Properties ---------------------------------------------------- */

:root {
  /* Palette */
  --bg:            #0a0a0c;
  --bg-raised:     #101014;
  --bg-sunken:     #060608;
  --bg-header:     rgba(10, 10, 12, 0.94);
  --text:          #d4d4d8;
  --text-dim:      #71717a;
  --text-faint:    #3f3f46;
  --white:         #e4e4e7;
  --accent:        #818cf8;
  --accent-dim:    rgba(129, 140, 248, 0.14);
  --accent-border: rgba(129, 140, 248, 0.3);
  --accent-text:   rgba(129, 140, 248, 0.8);
  --accent-glow:   rgba(129, 140, 248, 0.12);
  --accent-warm:   #c4b5fd;
  --surface:       rgba(228, 228, 231, 0.03);
  --rule:          rgba(228, 228, 231, 0.07);
  --rule-strong:   rgba(228, 228, 231, 0.14);

  /* Typography */
  --font-en:   'Inter', 'Helvetica Neue', Arial, sans-serif;
  --font-cn:   'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Consolas', monospace;

  /* Type Scale (strict) */
  --t0: 0.75rem;     /* 12px */
  --t1: 0.875rem;    /* 14px */
  --t2: 1rem;        /* 16px */
  --t3: 1.25rem;     /* 20px */
  --t4: 1.5rem;      /* 24px */
  --t5: 2rem;        /* 32px */
  --t6: 3rem;        /* 48px */
  --t7: 4.5rem;      /* 72px */
  --t8: 6rem;        /* 96px */
  --t9: 8rem;        /* 128px */

  /* Spacing Scale (strict) */
  --s0: 0.25rem;     /* 4px */
  --s1: 0.5rem;      /* 8px */
  --s2: 0.75rem;     /* 12px */
  --s3: 1rem;        /* 16px */
  --s4: 1.5rem;      /* 24px */
  --s5: 2rem;        /* 32px */
  --s6: 3rem;        /* 48px */
  --s7: 4rem;        /* 64px */
  --s8: 6rem;        /* 96px */
  --s9: 8rem;        /* 128px */

  /* Motion */
  --ease:        cubic-bezier(0.16, 1, 0.3, 1);
  --dur-micro:   120ms;
  --dur-panel:   240ms;
  --dur-section: 360ms;

  /* Z-Index */
  --z-texture:     -1;
  --z-content:      1;
  --z-overlay:     10;
  --z-nav:        100;
  --z-mobile-menu: 500;

  /* Layout */
  --grid-max:  1280px;
  --grid-cols: 12;
  --grid-gap:  var(--s4);

  /* Header */
  --header-h:  72px;
  --header-h-mobile: 64px;
}

/* --- Type Scale Classes --------------------------------------------------- */

.t0 { font-size: var(--t0); }
.t1 { font-size: var(--t1); }
.t2 { font-size: var(--t2); }
.t3 { font-size: var(--t3); }
.t4 { font-size: var(--t4); }
.t5 { font-size: var(--t5); }
.t6 { font-size: clamp(2rem, 4vw, var(--t6)); }
.t7 { font-size: clamp(2.5rem, 6vw, var(--t7)); }
.t8 { font-size: clamp(3rem, 8vw, var(--t8)); }
.t9 { font-size: clamp(4rem, 10vw, var(--t9)); }

.mono {
  font-family: var(--font-mono);
  letter-spacing: 0.05em;
  font-feature-settings: 'tnum' 1;
}

.cn {
  font-family: var(--font-cn);
  letter-spacing: 0;
}

.label {
  font-family: var(--font-mono);
  font-size: var(--t0);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-dim);
  font-weight: 500;
}

.label-sm {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-faint);
}

/* --- Layout System -------------------------------------------------------- */

.container {
  width: 100%;
  max-width: var(--grid-max);
  margin: 0 auto;
  padding-left: var(--s4);
  padding-right: var(--s4);
}

.grid {
  display: grid;
  grid-template-columns: repeat(var(--grid-cols), 1fr);
  gap: var(--grid-gap);
}

.col-1  { grid-column: span 1; }
.col-2  { grid-column: span 2; }
.col-3  { grid-column: span 3; }
.col-4  { grid-column: span 4; }
.col-5  { grid-column: span 5; }
.col-6  { grid-column: span 6; }
.col-7  { grid-column: span 7; }
.col-8  { grid-column: span 8; }
.col-9  { grid-column: span 9; }
.col-10 { grid-column: span 10; }
.col-11 { grid-column: span 11; }
.col-12 { grid-column: span 12; }

/* --- Rules & Dividers ----------------------------------------------------- */

.rule {
  width: 100%;
  height: 1px;
  background: var(--rule);
}

.rule-strong {
  background: var(--rule-strong);
}

.rule-accent {
  background: var(--accent-dim);
}

/* Accent square marker */
.rule-marker {
  position: relative;
}

.rule-marker::after {
  content: '';
  position: absolute;
  right: 0;
  top: -2px;
  width: 5px;
  height: 5px;
  background: var(--accent);
}

/* --- Scroll Reveal -------------------------------------------------------- */

.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 500ms var(--ease),
              transform 500ms var(--ease);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Ambient Textures ----------------------------------------------------- */

/* Scanlines */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 9998;
  pointer-events: none;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 2px,
    rgba(0, 0, 0, 0.06) 2px,
    rgba(0, 0, 0, 0.06) 4px
  );
  opacity: 0.7;
}

/* Noise */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 9997;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  opacity: 0.06;
}

/* Faint grid overlay */
.yl-grid {
  position: fixed;
  inset: 0;
  z-index: var(--z-texture);
  pointer-events: none;
  opacity: 0.07;
  background-image:
    linear-gradient(rgba(228, 228, 231, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(228, 228, 231, 0.04) 1px, transparent 1px);
  background-size: calc(var(--grid-max) / 12) calc(var(--grid-max) / 12);
  background-position: center;
}

/* --- Bilingual Language Mode ---------------------------------------------- */

/* Default: English primary */
[data-lang-mode="en-first"] .bilingual-en {
  display: block;
}

[data-lang-mode="en-first"] .bilingual-cn {
  display: block;
  font-family: var(--font-cn);
  font-size: 0.65em;
  color: var(--text-dim);
  margin-top: var(--s1);
}

/* Chinese-first mode */
[data-lang-mode="cn-first"] .bilingual-cn {
  display: block;
  font-family: var(--font-cn);
}

[data-lang-mode="cn-first"] .bilingual-en {
  display: block;
  font-size: 0.65em;
  color: var(--text-dim);
  margin-top: var(--s1);
}

/* Inline bilingual pairs (side by side) */
.bilingual-inline {
  display: flex;
  align-items: baseline;
  gap: var(--s2);
}

[data-lang-mode="cn-first"] .bilingual-inline {
  flex-direction: row-reverse;
}

/* --- Selection & Focus ---------------------------------------------------- */

::selection {
  background: var(--accent);
  color: var(--bg);
}

:focus-visible {
  outline: 1px solid var(--accent);
  outline-offset: 2px;
}

/* --- Scrollbar ------------------------------------------------------------ */

::-webkit-scrollbar {
  width: 3px;
}

::-webkit-scrollbar-track {
  background: var(--bg);
}

::-webkit-scrollbar-thumb {
  background: var(--text-faint);
}

/* --- Reduced Motion ------------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }

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

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

@media (max-width: 1023px) {
  :root {
    --grid-cols: 6;
    --header-h: 64px;
  }

  .col-7, .col-8, .col-9, .col-10, .col-11, .col-12 {
    grid-column: span 6;
  }

  .col-4, .col-5 {
    grid-column: span 3;
  }

  .col-3 {
    grid-column: span 3;
  }
}

@media (max-width: 639px) {
  :root {
    --grid-cols: 4;
  }

  .col-1, .col-2, .col-3, .col-4, .col-5, .col-6 {
    grid-column: span 4;
  }

  .container {
    padding-left: var(--s3);
    padding-right: var(--s3);
  }
}