/* One Bell — Website
   Monochrome. Dark only. No bold. No hue.
   Hierarchy through brightness, size, and space. */

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

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

/* ------------------------------------------------
   Tokens
   ------------------------------------------------ */

:root {
  --bg: #0C0C0C;
  --bg-surface: #131313;
  --text-1: #E0E0E0;
  --text-2: #9A9A9A;
  --text-3: #777777;
  --border-1: #2A2A2A;
  --border-2: #1C1C1C;

  --font: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --measure: 34rem;
  --measure-narrow: 28rem;
  --space-xs: 0.5rem;
  --space-s: 1rem;
  --space-m: 2rem;
  --space-l: 4rem;
  --space-xl: 8rem;
  --space-2xl: 12rem;
}

/* ------------------------------------------------
   Base
   ------------------------------------------------ */

html {
  background: var(--bg);
  color: var(--text-1);
  font-family: var(--font);
  font-weight: 400;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  min-height: 100dvh;
  overflow-x: hidden;
}

/* No bold — ever */
h1, h2, h3, h4, strong, b, th {
  font-weight: 400;
}

a {
  color: var(--text-2);
  text-decoration-line: underline;
  text-decoration-color: var(--border-1);
  text-underline-offset: 0.2em;
  transition: color 0.3s, text-decoration-color 0.3s;
}

a:hover {
  color: var(--text-1);
  text-decoration-color: var(--text-2);
}

/* Focus — visible for keyboard, hidden for mouse */
:focus-visible {
  outline: 1px solid var(--text-2);
  outline-offset: 3px;
}

::selection {
  background: rgba(255, 255, 255, 0.12);
}

/* Skip link — hidden until focused */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-m);
  padding: var(--space-xs) var(--space-s);
  background: var(--text-1);
  color: var(--bg);
  font-size: 0.8125rem;
  text-decoration: none;
  z-index: 100;
  border-radius: 0.25rem;
}

.skip-link:focus {
  top: var(--space-s);
}

/* ------------------------------------------------
   Scroll-reveal system
   Elements with [data-reveal] fade up on enter.
   ------------------------------------------------ */

[data-reveal] {
  opacity: 0;
  transform: translateY(1.5rem);
  transition:
    opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1),
    transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

[data-reveal].is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* ------------------------------------------------
   Layout primitives
   ------------------------------------------------ */

.page {
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* ------------------------------------------------
   Hero (landing page)
   ------------------------------------------------ */

.hero {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-l) var(--space-m);
  position: relative;
  overflow: hidden;
}

.hero-ring {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: min(70vw, 480px);
  height: min(70vw, 480px);
  pointer-events: none;
  opacity: 0;
  transition: opacity 1.2s ease;
}

.hero-ring.is-visible {
  opacity: 1;
}

.hero-ring circle {
  fill: none;
  stroke-linecap: round;
}

.hero-name {
  font-size: 0.75rem;
  color: var(--text-3);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: var(--space-m);
  position: relative;
  z-index: 1;
}

.hero-headline {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  line-height: 1.4;
  color: var(--text-1);
  letter-spacing: -0.025em;
  max-width: 20ch;
  margin-inline: auto;
  text-wrap: balance;
  position: relative;
  z-index: 1;
}

.hero-scroll-hint {
  position: absolute;
  bottom: var(--space-m);
  left: 50%;
  transform: translateX(-50%);
  width: 1px;
  height: 2.5rem;
  background: linear-gradient(to bottom, var(--text-3), transparent);
  opacity: 0;
  animation: scroll-hint 2s ease-in-out 1.5s infinite;
}

@keyframes scroll-hint {
  0%, 100% { opacity: 0; transform: translateX(-50%) translateY(0); }
  50% { opacity: 0.5; transform: translateX(-50%) translateY(0.5rem); }
}

@media (prefers-reduced-motion: reduce) {
  .hero-scroll-hint {
    animation: none;
    opacity: 0.3;
  }
}

/* ------------------------------------------------
   Statement (short copy blocks between sections)
   ------------------------------------------------ */

.statement {
  padding: var(--space-xl) var(--space-m);
  display: flex;
  justify-content: center;
}

.statement p {
  font-size: clamp(1.0625rem, 2.5vw, 1.1875rem);
  line-height: 1.85;
  color: var(--text-2);
  max-width: var(--measure-narrow);
  text-wrap: pretty;
}

/* ------------------------------------------------
   Screenshot
   ------------------------------------------------ */

.screenshot-band {
  padding: var(--space-xl) var(--space-m) var(--space-l);
  display: flex;
  justify-content: center;
}

.screenshot {
  position: relative;
  cursor: pointer;
}

.screenshot img {
  display: block;
  width: 560px;
  max-width: 100%;
  height: auto;
}

.screenshot-active {
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
  transition: opacity 0.8s ease;
}

.screenshot:hover .screenshot-active,
.screenshot.is-tapped .screenshot-active {
  opacity: 1;
}

/* Soft glow behind screenshot */
.screenshot::after {
  content: "";
  position: absolute;
  inset: 10% 5%;
  background: radial-gradient(ellipse, rgba(255, 255, 255, 0.03) 0%, transparent 70%);
  z-index: -1;
  filter: blur(40px);
}

@media (prefers-reduced-motion: reduce) {
  .screenshot-active {
    transition: none;
  }
}

/* ------------------------------------------------
   What's in. What's out.
   ------------------------------------------------ */

.inout {
  padding: var(--space-xl) var(--space-m);
  width: 100%;
}

.inout-inner {
  max-width: 44rem;
  margin-inline: auto;
}

.inout-heading {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  color: var(--text-1);
  letter-spacing: -0.025em;
  margin-bottom: var(--space-l);
  text-align: center;
}

/* Two columns side by side */
.inout-columns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-l);
  align-items: start;
}

/* Group spacing */
.inout-group {
  margin-bottom: 0;
}

@media (max-width: 600px) {
  .inout-columns {
    grid-template-columns: 1fr;
    gap: var(--space-l);
  }
}

/* Labels */
.inout-label {
  font-size: 0.6875rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-3);
  padding-bottom: var(--space-s);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.inout-label::before {
  content: "";
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: currentColor;
}

/* Flowing text blocks */
.inout-flow {
  font-size: 0.875rem;
  line-height: 1.75;
  text-wrap: pretty;
}

.inout-flow--in {
  color: var(--text-2);
}

.inout-flow--out {
  color: var(--text-3);
}

/* ------------------------------------------------
   Guides (card links to sub-pages)
   ------------------------------------------------ */

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

.guides-inner {
  max-width: var(--measure);
  margin-inline: auto;
}

.guides-label {
  font-size: 0.75rem;
  color: var(--text-3);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: var(--space-m);
}

.guides-list {
  list-style: none;
  display: flex;
  flex-direction: column;
}

.guides-list li + li {
  border-top: 1px solid var(--border-2);
}

.guide-link {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-s);
  padding: var(--space-s) 0;
  text-decoration: none;
  transition: opacity 0.2s;
}

.guide-link:hover {
  text-decoration: none;
}

.guide-link-title {
  font-size: 0.9375rem;
  color: var(--text-2);
  transition: color 0.3s;
}

.guide-link:hover .guide-link-title {
  color: var(--text-1);
}

.guide-link-desc {
  font-size: 0.8125rem;
  color: var(--text-3);
  text-align: right;
  transition: color 0.3s;
}

.guide-link:hover .guide-link-desc {
  color: var(--text-2);
}

@media (max-width: 540px) {
  .guide-link {
    flex-direction: column;
    gap: 0.125rem;
  }

  .guide-link-desc {
    text-align: left;
  }
}

/* ------------------------------------------------
   Download link
   ------------------------------------------------ */

.download {
  padding: var(--space-l) var(--space-m);
  text-align: center;
}

.download a {
  font-size: 0.875rem;
  color: var(--text-2);
  text-decoration: none;
  letter-spacing: 0.02em;
  padding: 0.625rem 1.5rem;
  border: 1px solid var(--border-1);
  border-radius: 2rem;
  display: inline-block;
  transition: color 0.3s, border-color 0.3s;
}

.download a:hover {
  color: var(--text-1);
  border-color: var(--text-3);
  text-decoration: none;
}

/* ------------------------------------------------
   Footer
   ------------------------------------------------ */

.footer {
  padding: var(--space-m);
  text-align: center;
  font-size: 0.6875rem;
  color: var(--text-3);
  letter-spacing: 0.05em;
}

/* ------------------------------------------------
   Sub-page layout
   ------------------------------------------------ */

.sub-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100dvh;
  padding: var(--space-l) var(--space-m) var(--space-2xl);
}

.sub-content {
  width: 100%;
  max-width: var(--measure);
}

.back-link {
  display: inline-block;
  font-size: 0.8125rem;
  color: var(--text-3);
  text-decoration: none;
  margin-bottom: var(--space-l);
  transition: color 0.3s;
}

.back-link:hover {
  color: var(--text-2);
  text-decoration: none;
}

/* ------------------------------------------------
   Section (sub-pages)
   ------------------------------------------------ */

.sub-title {
  font-size: clamp(1.25rem, 3vw, 1.625rem);
  color: var(--text-1);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-l);
  text-wrap: balance;
}

.sub-intro {
  font-size: 1.0625rem;
  color: var(--text-2);
  line-height: 1.85;
  margin-bottom: var(--space-l);
  max-width: var(--measure-narrow);
  text-wrap: pretty;
}

.section {
  margin-bottom: var(--space-l);
}

.section + .section {
  padding-top: var(--space-l);
  border-top: 1px solid var(--border-2);
}

.section-heading {
  font-size: 0.75rem;
  color: var(--text-3);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: var(--space-m);
}

.section p {
  font-size: 0.9375rem;
  color: var(--text-2);
  line-height: 1.8;
  max-width: var(--measure-narrow);
  text-wrap: pretty;
}

.section p + p {
  margin-top: var(--space-s);
}

/* ------------------------------------------------
   Steps
   ------------------------------------------------ */

.steps {
  list-style: none;
  counter-reset: step;
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

.steps li {
  counter-increment: step;
  font-size: 0.9375rem;
  color: var(--text-2);
  line-height: 1.7;
  padding-left: 2.25rem;
  position: relative;
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  color: var(--text-3);
  font-size: 0.75rem;
  font-variant-numeric: tabular-nums;
  line-height: 1.7;
  top: 0.15em;
}

/* ------------------------------------------------
   Aside (callout text)
   ------------------------------------------------ */

.aside {
  font-size: 0.9375rem;
  color: var(--text-3);
  line-height: 1.8;
  margin-top: var(--space-m);
  padding-left: var(--space-m);
  border-left: 1px solid var(--border-2);
  max-width: var(--measure-narrow);
}

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

@media (max-width: 480px) {
  :root {
    --space-xl: 5rem;
    --space-2xl: 7rem;
  }

  .hero {
    padding: var(--space-m);
  }

  .hero-name {
    margin-bottom: var(--space-m);
  }
}