/* =============================================================
   StudyNect — Base Stylesheet
   Tokens · Typography · Reset · Motion primitives
   ============================================================= */

/* Slimmed: only the weights we actually render. Cut 300/700/800/900 + the
   Instrument Serif regular face (we only use the italic). Saves ~5 font
   files / ~120 KB on first load. */
@import url("https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600&family=Instrument+Serif:ital@1&display=swap");

:root {
  /* Brand — hero, grounded white */
  --bg: #ffffff;
  --bg-soft: #f5f5f5;
  --bg-ink: #0a0a0a;
  --ink: #111111;
  --ink-soft: #666666;
  --ink-hairline: rgba(17, 17, 17, 0.08);
  --ink-hairline-strong: rgba(17, 17, 17, 0.14);

  /* Four figures in orbit — pink, blue, orange, green */
  --pink: #ff1fa9;
  --blue: #38b6ff;
  --orange: #fea51f;
  --green: #74cc00;

  /* Gentle tinted backgrounds (~6% of each hue) for chapter moments */
  --pink-wash: #fff2fa;
  --blue-wash: #ebf8ff;
  --orange-wash: #fff7e8;
  --green-wash: #f3fbe0;

  /* Glows used behind the orbit hero */
  --pink-glow: rgba(255, 31, 169, 0.35);
  --blue-glow: rgba(56, 182, 255, 0.35);
  --orange-glow: rgba(254, 165, 31, 0.35);
  --green-glow: rgba(116, 204, 0, 0.35);

  /* Fluid type — based on viewport width, but bounded */
  --step--1: clamp(0.9rem, 0.85rem + 0.25vw, 1rem);
  --step-0: clamp(1rem, 0.95rem + 0.3vw, 1.125rem);
  --step-1: clamp(1.125rem, 1rem + 0.6vw, 1.35rem);
  --step-2: clamp(1.35rem, 1.15rem + 1vw, 1.75rem);
  --step-3: clamp(1.75rem, 1.4rem + 1.6vw, 2.5rem);
  --step-4: clamp(2.25rem, 1.6rem + 3vw, 3.75rem);
  --step-5: clamp(3rem, 2rem + 5vw, 6rem);
  --step-6: clamp(4rem, 2.2rem + 9vw, 10rem);
  --step-7: clamp(5rem, 2.5rem + 13vw, 14rem);

  /* Rhythm */
  --space-1: clamp(0.25rem, 0.2rem + 0.2vw, 0.375rem);
  --space-2: clamp(0.5rem, 0.4rem + 0.3vw, 0.75rem);
  --space-3: clamp(0.75rem, 0.6rem + 0.5vw, 1.125rem);
  --space-4: clamp(1rem, 0.8rem + 0.7vw, 1.5rem);
  --space-5: clamp(1.5rem, 1.1rem + 1.2vw, 2.5rem);
  --space-6: clamp(2rem, 1.4rem + 2vw, 4rem);
  --space-7: clamp(3rem, 2rem + 3.5vw, 6rem);
  --space-8: clamp(4rem, 2.5rem + 5vw, 8rem);
  --space-9: clamp(6rem, 3rem + 8vw, 12rem);

  /* Layout */
  --max: 1440px;
  --gutter: clamp(1.25rem, 1rem + 1.5vw, 2.5rem);
  --radius-s: 10px;
  --radius-m: 18px;
  --radius-l: 28px;
  --radius-xl: 40px;

  /* Motion */
  --ease-out: cubic-bezier(0.2, 0.7, 0.2, 1);
  --ease-in-out: cubic-bezier(0.65, 0.05, 0.35, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  --t-fast: 160ms;
  --t-med: 320ms;
  --t-slow: 640ms;
  --t-cinematic: 1200ms;

  /* Header shell */
  --nav-h: 72px;
}

/* Respect system preference */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* --------- Reset --------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

html {
  font-size: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  background: var(--bg);
  color: var(--ink);
}

body {
  font-family: "Poppins", system-ui, -apple-system, "Segoe UI", sans-serif;
  font-weight: 400;
  font-size: var(--step-0);
  line-height: 1.55;
  color: var(--ink);
  background: var(--bg);
  overflow-x: clip;
  min-height: 100vh;
}

img,
svg,
video {
  display: block;
  max-width: 100%;
  height: auto;
}

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

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

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 0;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.02;
}

p {
  margin: 0;
}

::selection {
  background: var(--pink);
  color: #fff;
}

/* --------- Typography scale --------- */
.eyebrow {
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink-soft);
  display: inline-flex;
  align-items: center;
  gap: 0.6em;
}
.eyebrow::before {
  content: "";
  width: 20px;
  height: 1px;
  background: currentColor;
  opacity: 0.5;
  display: inline-block;
}

.display {
  font-family: "Poppins", sans-serif;
  font-weight: 600;
  font-size: clamp(2.5rem, 1.6rem + 4vw, 5.5rem);
  line-height: 0.98;
  letter-spacing: -0.035em;
}

.display--xl {
  font-size: var(--step-7);
  font-weight: 700;
  line-height: 0.88;
  letter-spacing: -0.04em;
}

.serif {
  font-family: "Instrument Serif", "Times New Roman", serif;
  font-style: italic;
  font-weight: 400;
  letter-spacing: -0.01em;
}

.h1 {
  font-size: var(--step-5);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 0.98;
}

.h2 {
  font-size: var(--step-4);
  font-weight: 600;
  letter-spacing: -0.025em;
  line-height: 1.02;
}

.h3 {
  font-size: var(--step-3);
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.08;
}

.lead {
  font-size: var(--step-2);
  color: var(--ink-soft);
  font-weight: 400;
  line-height: 1.35;
  max-width: 52ch;
}

.body {
  font-size: var(--step-0);
  color: var(--ink-soft);
  line-height: 1.6;
  max-width: 62ch;
}

.muted {
  color: var(--ink-soft);
}

.mono {
  font-family: ui-monospace, "SFMono-Regular", Menlo, Monaco, Consolas, monospace;
  font-size: 0.78rem;
  letter-spacing: 0.04em;
}

/* Highlighting words in display copy (brand colors) */
.hl {
  position: relative;
  display: inline-block;
  color: var(--ink);
}
.hl[data-hl="pink"] {
  color: var(--pink);
}
.hl[data-hl="blue"] {
  color: var(--blue);
}
.hl[data-hl="orange"] {
  color: var(--orange);
}
.hl[data-hl="green"] {
  color: var(--green);
}

/* Underline swash — used on hero verbs */
.swash {
  position: relative;
  white-space: nowrap;
}
.swash::after {
  content: "";
  position: absolute;
  left: -0.04em;
  right: -0.04em;
  bottom: 0.02em;
  height: 0.12em;
  background: currentColor;
  opacity: 0.18;
  border-radius: 999px;
  transform-origin: left center;
  transform: scaleX(0);
  animation: swashIn 900ms var(--ease-out) 600ms forwards;
}
@keyframes swashIn {
  to {
    transform: scaleX(1);
  }
}

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

.section {
  padding: var(--space-9) 0;
  position: relative;
}

.section--tight {
  padding: var(--space-7) 0;
}

.grid {
  display: grid;
  gap: var(--space-5);
}
.grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}
.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}
.grid-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}
@media (max-width: 880px) {
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }
}

.flex {
  display: flex;
}
.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}
.stack {
  display: flex;
  flex-direction: column;
}
.stack > * + * {
  margin-top: var(--gap, var(--space-4));
}

/* Hairline divider like a thin-film */
.hr {
  height: 1px;
  background: var(--ink-hairline);
  border: 0;
  margin: 0;
}

/* Noise / film grain — subtle paper warmth */
.grain::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.045;
  z-index: 9998;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.8 0'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
  mix-blend-mode: multiply;
}

/* --------- Buttons & pill ctas --------- */
.btn {
  --btn-bg: var(--ink);
  --btn-fg: #fff;
  --btn-border: transparent;
  display: inline-flex;
  align-items: center;
  gap: 0.6em;
  padding: 0.95em 1.4em;
  background: var(--btn-bg);
  color: var(--btn-fg);
  border: 1px solid var(--btn-border);
  border-radius: 999px;
  font-weight: 500;
  font-size: 0.98rem;
  letter-spacing: -0.005em;
  transition:
    transform var(--t-fast) var(--ease-out),
    background var(--t-med) var(--ease-out),
    color var(--t-med) var(--ease-out),
    box-shadow var(--t-med) var(--ease-out);
  will-change: transform;
}
.btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 30px -12px rgba(0, 0, 0, 0.3);
}
.btn:active {
  transform: translateY(0);
}
.btn .arrow {
  width: 1em;
  height: 1em;
  transition: transform var(--t-med) var(--ease-out);
}
.btn:hover .arrow {
  transform: translateX(3px);
}

.btn--pink {
  --btn-bg: var(--pink);
}
.btn--blue {
  --btn-bg: var(--blue);
}
.btn--orange {
  --btn-bg: var(--orange);
}
.btn--green {
  --btn-bg: var(--green);
}
.btn--ghost {
  --btn-bg: transparent;
  --btn-fg: var(--ink);
  --btn-border: var(--ink-hairline-strong);
}
.btn--ghost:hover {
  --btn-bg: var(--ink);
  --btn-fg: #fff;
  --btn-border: var(--ink);
}

/* Oversized rallying-call CTA */
.rally {
  display: inline-flex;
  align-items: baseline;
  gap: 0.4em;
  font-size: var(--step-3);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: 1;
  padding: 0.7em 1em;
  border: 1px solid var(--ink-hairline-strong);
  border-radius: 999px;
  color: var(--ink);
  background: #fff;
  transition:
    background var(--t-med) var(--ease-out),
    color var(--t-med) var(--ease-out),
    border-color var(--t-med) var(--ease-out);
}
.rally:hover {
  background: var(--ink);
  color: #fff;
  border-color: var(--ink);
}

/* --------- Reveal on scroll --------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition:
    opacity 900ms var(--ease-out),
    transform 900ms var(--ease-out);
}
[data-reveal].is-in {
  opacity: 1;
  transform: none;
}
[data-reveal="stagger"] > * {
  opacity: 0;
  transform: translateY(18px);
  transition:
    opacity 800ms var(--ease-out),
    transform 800ms var(--ease-out);
  transition-delay: calc(var(--i, 0) * 70ms);
}
[data-reveal="stagger"].is-in > * {
  opacity: 1;
  transform: none;
}

/* Split text — letter-by-letter reveal */
.split .ch {
  display: inline-block;
  transform: translateY(110%);
  transition: transform 900ms var(--ease-out);
  transition-delay: calc(var(--i, 0) * 18ms);
}
.split .word {
  display: inline-block;
  overflow: hidden;
  line-height: 1.05;
  padding-bottom: 0.05em;
}
.split.is-in .ch {
  transform: none;
}

/* =============================================================
   Mobile refinements (≤640px / ≤480px)
   Token overrides + global tweaks for phone-class viewports.
   ============================================================= */

@media (max-width: 640px) {
  :root {
    /* Tighten vertical rhythm on phones — sections feel less endless */
    --space-7: clamp(2rem, 1.5rem + 2vw, 3.5rem);
    --space-8: clamp(2.5rem, 1.8rem + 2.5vw, 4.5rem);
    --space-9: clamp(3rem, 2rem + 3vw, 5rem);
    /* Slightly tighter side padding on small phones */
    --gutter: clamp(1rem, 0.8rem + 1vw, 1.5rem);
    /* Slimmer header so hero gets more room */
    --nav-h: 64px;
  }

  /* Cap the largest display step so hero/CTA titles don't dominate */
  body {
    line-height: 1.5;
  }

  .h1 {
    line-height: 1.02;
  }
  .h2,
  .h3 {
    line-height: 1.08;
  }
  .lead {
    line-height: 1.4;
  }

  /* Buttons keep a comfortable 44px touch target on phones */
  .btn {
    padding: 0.85em 1.2em;
    font-size: 0.96rem;
    min-height: 44px;
  }
  .rally {
    font-size: var(--step-2);
    padding: 0.6em 0.9em;
  }

  /* Section spacing: keep top/bottom equal but trimmer */
  .section {
    padding: var(--space-8) 0;
  }
  .section--tight {
    padding: var(--space-6) 0;
  }
}

@media (max-width: 480px) {
  :root {
    --space-7: clamp(1.75rem, 1.2rem + 2vw, 3rem);
    --space-8: clamp(2rem, 1.4rem + 2.5vw, 4rem);
    --space-9: clamp(2.5rem, 1.6rem + 3vw, 4.5rem);
    --gutter: 1rem;
  }

  /* Reduce expensive split-letter staggers on tiny screens */
  .split .ch {
    transition-duration: 600ms;
  }
}