/* ============================================================
   DS MIDTERM — base layer: tokens, reset, layout, typography
   ============================================================ */
@import url("../fonts/fonts.css");

:root {
  --bg:            #070a12;
  --bg-2:          #0b1020;
  --bg-3:          #101731;
  --panel:         rgba(20, 28, 51, 0.62);
  --panel-solid:   #121a30;
  --line:          rgba(140, 165, 220, 0.16);
  --line-strong:   rgba(140, 165, 220, 0.34);

  --ink:           #e9eefb;
  --ink-2:         #b9c4de;
  --ink-3:         #8492b4;
  --ink-4:         #5d6a8a;

  --cyan:          #4fd8e8;
  --cyan-deep:     #1f9fb5;
  --violet:        #9b7bf6;
  --amber:         #ffb454;
  --rose:          #ff6f91;
  --green:         #5ce1a6;
  --blue:          #5b8cff;

  --c1: #4fd8e8;
  --c2: #9b7bf6;
  --c3: #ffb454;
  --c4: #ff6f91;
  --c5: #5ce1a6;
  --c6: #5b8cff;

  --radius: 18px;
  --radius-sm: 11px;
  --shadow: 0 24px 70px -30px rgba(0, 0, 0, 0.9);
  --maxw: 1180px;

  --font-sans: "Inter", "Segoe UI", system-ui, sans-serif;
  --font-disp: "Space Grotesk", "Inter", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "Cascadia Code", ui-monospace, Consolas, monospace;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16.5px;
  line-height: 1.72;
  letter-spacing: 0.002em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* aurora backdrop */
body::before {
  content: "";
  position: fixed;
  inset: -20vh -10vw;
  z-index: -2;
  background:
    radial-gradient(48vw 48vw at 12% -6%, rgba(79, 216, 232, 0.16), transparent 62%),
    radial-gradient(46vw 46vw at 88% 8%, rgba(155, 123, 246, 0.17), transparent 60%),
    radial-gradient(52vw 40vw at 50% 106%, rgba(91, 140, 255, 0.13), transparent 66%);
  filter: blur(6px);
  pointer-events: none;
}

body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(rgba(140, 165, 220, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(140, 165, 220, 0.045) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(circle at 50% 24%, #000 0%, transparent 82%);
  -webkit-mask-image: radial-gradient(circle at 50% 24%, #000 0%, transparent 82%);
  pointer-events: none;
}

img { max-width: 100%; display: block; }

a { color: var(--cyan); text-decoration: none; }
a:hover { color: #9deef8; }

::selection { background: rgba(79, 216, 232, 0.28); color: #fff; }

/* ---------- scrollbar ---------- */
::-webkit-scrollbar { width: 11px; height: 11px; }
::-webkit-scrollbar-track { background: #080c16; }
::-webkit-scrollbar-thumb {
  background: linear-gradient(#2b3a5e, #1b2440);
  border-radius: 99px;
  border: 2px solid #080c16;
}
::-webkit-scrollbar-thumb:hover { background: linear-gradient(#3a4d78, #232e50); }

/* ============================================================
   TYPOGRAPHY
   ============================================================ */
h1, h2, h3, h4, h5 {
  font-family: var(--font-disp);
  font-weight: 600;
  line-height: 1.14;
  letter-spacing: -0.022em;
  margin: 0 0 0.5em;
  color: #fff;
}

h2 { font-size: clamp(1.9rem, 3.4vw, 2.9rem); }
h3 { font-size: clamp(1.28rem, 1.9vw, 1.62rem); }
h4 { font-size: 1.06rem; letter-spacing: -0.01em; }

p { margin: 0 0 1.05em; color: var(--ink-2); }
p strong, li strong { color: #fff; font-weight: 600; }
em { color: var(--ink); font-style: italic; }

.lead {
  font-size: 1.1rem;
  line-height: 1.78;
  color: var(--ink-2);
}

.muted { color: var(--ink-3); }
.small { font-size: 0.875rem; line-height: 1.62; }
.tiny  { font-size: 0.78rem; line-height: 1.55; }
.mono  { font-family: var(--font-mono); font-size: 0.86em; letter-spacing: -0.01em; }

.grad-text {
  background: linear-gradient(96deg, #7ff0ff 0%, #b39bff 46%, #ffc07a 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* ============================================================
   LAYOUT
   ============================================================ */
.wrap {
  width: min(100% - 3rem, var(--maxw));
  margin-inline: auto;
}

section.unit {
  position: relative;
  padding: clamp(4.5rem, 9vw, 8rem) 0 clamp(4rem, 7vw, 7rem);
  border-top: 1px solid var(--line);
  scroll-margin-top: 76px;
}

section.unit:first-of-type { border-top: 0; }

.grid { display: grid; gap: 1.15rem; }
.g2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.g3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.g4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.g-2-1 { grid-template-columns: 1.45fr 1fr; }
.g-1-2 { grid-template-columns: 1fr 1.45fr; }

.stack-sm > * + * { margin-top: 0.55rem; }
.stack > * + * { margin-top: 1.1rem; }
.stack-lg > * + * { margin-top: 1.9rem; }

.center { text-align: center; }

@media (max-width: 940px) {
  .g2, .g3, .g4, .g-2-1, .g-1-2 { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 620px) {
  body { font-size: 15.6px; }
  .wrap { width: min(100% - 1.7rem, var(--maxw)); }
}