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

:root {
  --ink: #111;
  --paper: #fff;
  --tracked: #3700de;
  --cell-size: clamp(4px, 0.85vw, 9px);
  --cell-gap: 1px;
  --group-gap: 3px;
  --label-size: clamp(0.55rem, 1.1vw, 0.72rem);
}

html {
  background: var(--paper);
}

body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: clamp(1rem, 3vw, 2.5rem);
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--paper);
}

.poster {
  width: min(100%, 980px);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: clamp(0.75rem, 2vw, 1.25rem);
}

.title {
  font-size: clamp(1.1rem, 2.8vw, 1.65rem);
  font-weight: 500;
  letter-spacing: 0.28em;
  text-align: center;
}

.subtitle {
  font-size: clamp(0.65rem, 1.5vw, 0.85rem);
  letter-spacing: 0.22em;
  text-align: center;
}

.stats {
  font-size: var(--label-size);
  letter-spacing: 0.08em;
  color: #444;
  text-align: center;
}

.calendar {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: start;
  gap: clamp(0.35rem, 1vw, 0.75rem);
  width: 100%;
}

.age-labels {
  display: flex;
  flex-direction: column;
  gap: var(--cell-gap);
  padding-top: calc(var(--label-size) + 0.45rem);
  font-size: var(--label-size);
  line-height: 1;
  text-align: right;
  padding-right: 0.35rem;
}

.age-label-row {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  height: var(--cell-size);
}

.age-label-row.group-end {
  margin-bottom: var(--group-gap);
}

.grid-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 0;
  overflow: visible;
}

.week-labels {
  display: flex;
  gap: var(--cell-gap);
  width: fit-content;
  max-width: 100%;
  margin-bottom: 0.35rem;
  font-size: var(--label-size);
  line-height: 1;
}

.week-label {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--cell-size);
  height: var(--label-size);
}

.week-label.group-end {
  margin-right: var(--group-gap);
}

.grid {
  display: flex;
  flex-direction: column;
  gap: var(--cell-gap);
  width: fit-content;
  max-width: 100%;
  overflow: visible;
}

.row {
  display: flex;
  gap: var(--cell-gap);
  overflow: visible;
}

.row.group-end {
  margin-bottom: var(--group-gap);
}

.cell {
  width: var(--cell-size);
  height: var(--cell-size);
  border: 1px solid var(--ink);
  background: var(--paper);
}

.cell.filled {
  background: var(--ink);
}

.cell.tracked {
  background: var(--tracked);
  border-color: var(--tracked);
}

.cell.milestone {
  position: relative;
  cursor: pointer;
  z-index: 1;
}

.cell.milestone::after {
  content: attr(data-tooltip);
  position: absolute;
  left: 50%;
  bottom: calc(100% + 8px);
  transform: translateX(-50%) translateY(4px);
  width: max-content;
  max-width: min(220px, 70vw);
  padding: 0.55rem 0.7rem;
  background: var(--ink);
  color: var(--paper);
  font-size: 0.7rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  line-height: 1.35;
  text-align: left;
  white-space: normal;
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.15s ease, transform 0.15s ease, visibility 0.15s ease;
  z-index: 20;
}

.cell.milestone::before {
  content: "";
  position: absolute;
  left: 50%;
  bottom: calc(100% + 2px);
  transform: translateX(-50%);
  border: 5px solid transparent;
  border-top-color: var(--ink);
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.15s ease, visibility 0.15s ease;
  z-index: 20;
}

.cell.milestone:hover,
.cell.milestone:focus-visible {
  z-index: 30;
  outline: 1px solid var(--tracked);
  outline-offset: 1px;
}

.cell.milestone:hover::after,
.cell.milestone:focus-visible::after {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.cell.milestone:hover::before,
.cell.milestone:focus-visible::before {
  opacity: 1;
  visibility: visible;
}

.cell.group-end-col {
  margin-right: var(--group-gap);
}

.weeks-caption {
  margin-top: 0.45rem;
  font-size: var(--label-size);
  letter-spacing: 0.18em;
}

.age-axis {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15rem;
  padding-top: calc(var(--label-size) + 0.45rem);
  font-size: var(--label-size);
  letter-spacing: 0.12em;
}

.age-arrow {
  font-size: calc(var(--label-size) * 1.1);
  line-height: 1;
}

.age-text {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  transform: rotate(180deg);
}

@media (max-width: 640px) {
  body {
    align-items: flex-start;
  }

  .calendar {
    overflow-x: auto;
    padding-bottom: 0.5rem;
  }
}