:root {
  color-scheme: light;
  --ink: #1f2937;
  --muted: #687385;
  --paper: #ffffff;
  --line: #d8dee8;
  --field: #f8fafc;
  --shadow: 0 18px 50px rgba(30, 41, 59, 0.12);
  --teal: #0f9f9a;
  --coral: #f45d48;
  --blue: #2563eb;
  --gold: #d99416;
  --plum: #7c3aed;
  --manual-primary: #0f766e;
  --manual-primary-dark: #115e59;
  --manual-secondary: #e85d4f;
  --manual-tertiary: #2563eb;
  --manual-warm: #d99416;
  --manual-bg-start: #fbfefd;
  --manual-bg-mid: #e9f6f4;
  --manual-bg-end: #f5faf9;
  --manual-header: rgba(248, 252, 251, 0.94);
  --manual-ring: rgba(15, 118, 110, 0.22);
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  background: var(--manual-bg-mid);
}

body {
  min-height: 100%;
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(180deg, var(--manual-bg-start) 0, var(--manual-bg-mid) 310px, var(--manual-bg-end) 100%);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  letter-spacing: 0;
}

button,
input {
  font: inherit;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid rgba(15, 118, 110, 0.24);
  background: var(--manual-header);
  backdrop-filter: blur(16px);
}

.header-inner {
  width: min(1120px, calc(100% - 32px));
  min-height: 118px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(180px, 0.45fr) minmax(320px, 0.9fr);
  gap: 28px;
  align-items: center;
}

.brand-block {
  display: grid;
  gap: 2px;
}

.eyebrow {
  margin: 0;
  color: var(--manual-secondary);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  color: var(--manual-primary-dark);
  font-size: clamp(2.1rem, 4vw, 4rem);
  line-height: 0.94;
  letter-spacing: 0;
}

.hash-form {
  display: grid;
  gap: 9px;
}

.hash-form label {
  color: var(--muted);
  font-size: 0.83rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.control-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
}

.control-row input {
  width: 100%;
  min-width: 0;
  min-height: 50px;
  border: 1px solid #cbd5e1;
  border-radius: 8px;
  padding: 0 16px;
  color: var(--ink);
  background: var(--paper);
  box-shadow: inset 0 1px 0 rgba(148, 163, 184, 0.16);
}

.control-row input:focus {
  outline: 3px solid var(--manual-ring);
  border-color: var(--manual-primary);
}

.control-row button {
  min-width: 120px;
  min-height: 50px;
  border: 0;
  border-radius: 8px;
  padding: 0 20px;
  color: #ffffff;
  background: var(--manual-primary-dark);
  font-weight: 800;
  cursor: pointer;
  transition: transform 160ms ease, background 160ms ease;
}

.control-row button:hover {
  transform: translateY(-1px);
  background: var(--manual-primary);
}

.page-shell {
  width: min(1020px, calc(100% - 28px));
  margin: 34px auto 76px;
}

.status-panel {
  display: none;
  margin-bottom: 24px;
  border: 1px solid #cbd5e1;
  border-left: 6px solid var(--manual-primary);
  border-radius: 8px;
  padding: 18px 20px;
  background: var(--paper);
  box-shadow: 0 8px 28px rgba(15, 23, 42, 0.08);
}

.status-panel.is-visible {
  display: block;
}

.status-panel strong {
  display: block;
  margin-bottom: 4px;
  color: #111827;
  font-size: 1rem;
}

.status-panel p {
  margin: 0;
  color: var(--muted);
}

.exercise-stack {
  display: grid;
  gap: 0;
}

.exercise-card {
  --accent: var(--manual-primary);
  overflow: hidden;
  border: 1px solid rgba(148, 163, 184, 0.42);
  border-radius: 8px;
  background: var(--paper);
  box-shadow: var(--shadow);
}

.exercise-card:nth-of-type(8n + 1) {
  --accent: var(--manual-primary);
}

.exercise-card:nth-of-type(8n + 3) {
  --accent: var(--manual-secondary);
}

.exercise-card:nth-of-type(8n + 5) {
  --accent: var(--manual-tertiary);
}

.exercise-card:nth-of-type(8n + 7) {
  --accent: var(--manual-warm);
}

.exercise-heading {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  align-items: center;
  border-bottom: 1px solid rgba(148, 163, 184, 0.35);
  padding: 15px 18px;
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--accent) 12%, #ffffff), #ffffff 70%);
}

.exercise-kicker {
  min-width: 36px;
  border: 2px solid var(--accent);
  border-radius: 8px;
  padding: 5px 9px 6px;
  color: var(--accent);
  background: #ffffff;
  font-size: 0.84rem;
  font-weight: 900;
  line-height: 1;
  text-align: center;
}

.exercise-heading h2 {
  margin: 0;
  color: #111827;
  font-size: clamp(1.16rem, 2.2vw, 1.65rem);
  line-height: 1.12;
  letter-spacing: 0;
}

.image-frame {
  padding: clamp(14px, 3vw, 28px);
  background: #ffffff;
}

.image-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
}

.exercise-card.is-error {
  border-color: rgba(244, 93, 72, 0.45);
}

.exercise-card.is-error .exercise-heading {
  background: #fff4f2;
}

.missing-box {
  min-height: 130px;
  display: grid;
  place-items: center;
  border: 1px dashed #f19a8d;
  border-radius: 8px;
  color: #9f2f22;
  background: #fff8f6;
  font-weight: 800;
  text-align: center;
}

.exercise-separator {
  width: 100%;
  height: 30px;
  margin: 28px 0;
  position: relative;
}

.exercise-separator::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 2px;
  background: linear-gradient(90deg, transparent, #94a3b8 12%, #94a3b8 88%, transparent);
}

.exercise-separator::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  width: 90px;
  height: 8px;
  border-radius: 8px;
  background: linear-gradient(90deg, var(--manual-primary), var(--manual-secondary), var(--manual-tertiary));
  transform: translate(-50%, -50%);
}

@media (max-width: 720px) {
  .header-inner {
    min-height: 150px;
    grid-template-columns: 1fr;
    gap: 16px;
    padding: 18px 0;
  }

  .control-row {
    grid-template-columns: 1fr;
  }

  .control-row button {
    width: 100%;
  }

  .page-shell {
    width: min(100% - 18px, 1020px);
    margin-top: 18px;
  }

  .exercise-heading {
    align-items: flex-start;
  }

  .image-frame {
    padding: 10px;
  }
}

@media print {
  body {
    background: #ffffff;
  }

  .app-header,
  .status-panel,
  .exercise-separator {
    display: none;
  }

  .page-shell {
    width: 100%;
    margin: 0;
  }

  .exercise-card {
    break-inside: avoid;
    box-shadow: none;
    border-color: #a8b0bd;
    margin-bottom: 18px;
  }
}