:root {
  color-scheme: dark;
  --accent: #93c5fd;
  --accent-soft: #192d48;
  --accent-solid: #2563eb;
  --bg: #0b1120;
  --card: #131e30;
  --text: #e5edf8;
  --muted: #a4b3c8;
  --border: #334155;
  --shadow: 0 18px 50px rgba(0, 0, 0, .24);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--text);
  background: var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
.page { width: min(1180px, calc(100% - 32px)); margin: 0 auto; padding: 24px 0 48px; }
.hero { margin-bottom: 18px; }
.hero h1 { margin: 0; font-size: clamp(26px, 4vw, 42px); line-height: 1.1; letter-spacing: -.03em; }
.hero p { margin: 8px 0 0; color: var(--muted); font-size: 15px; }
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  position: sticky;
  top: 0;
  z-index: 10;
  padding: 12px 0;
  margin-bottom: 18px;
  background: rgba(11, 17, 32, .94);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.tab-btn {
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 9px 15px;
  color: var(--text);
  background: var(--card);
  font-size: 14px;
  font-weight: 650;
  cursor: pointer;
}
.tab-btn:hover { border-color: var(--accent); }
.tab-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.tab-btn[aria-selected="true"] { color: #fff; background: var(--accent-solid); border-color: var(--accent-solid); }
.panel { display: none; }
.panel.active { display: block; }
.overview-card, .day-card {
  border: 1px solid var(--border);
  border-radius: 22px;
  padding: clamp(18px, 3vw, 32px);
  background: var(--card);
  box-shadow: var(--shadow);
}
.overview-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.overview-top strong { display: block; font-size: 18px; }
.meta { margin-top: 4px; color: var(--muted); font-size: 13px; }
.docx-text { font-size: 15px; line-height: 1.65; }
.docx-text h2 { margin: 12px 0 18px; font-size: 23px; line-height: 1.25; }
.docx-text h3 { margin: 24px 0 8px; font-size: 18px; line-height: 1.35; }
.docx-text p { margin: 10px 0; }
.callout { padding: 11px 13px; border-left: 4px solid var(--accent); border-radius: 10px; background: var(--accent-soft); font-weight: 800; }
.day-card h2 { margin: 0 0 18px; font-size: 28px; }
.set-title { max-width: 880px; margin: 32px auto 14px; padding: 12px 16px; border-radius: 14px; background: #24364f; color: var(--text); font-size: 19px; line-height: 1.35; }
.exercise-text { margin: 14px auto; max-width: 880px; font-size: 17px; line-height: 1.55; }
.exercise-title { margin-top: 20px; padding: 14px 16px; border-radius: 14px; background: var(--accent-soft); font-weight: 800; }
.alternative-title { width: fit-content; margin-top: 20px; padding: 6px 10px; border-radius: 999px; color: var(--accent); background: var(--accent-soft); font-weight: 800; }
.exercise-media { margin: 16px auto 22px; max-width: 760px; text-align: center; }
/* Preserve the original illustration colors, including transparent GIF backgrounds. */
.exercise-media img { display: block; max-width: 100%; height: auto; margin: 0 auto; border-radius: 14px; border: 1px solid var(--border); background: #fff; }
hr { max-width: 880px; margin: 24px auto; border: 0; border-top: 1px solid var(--border); }

@media (max-width: 720px) {
  .page { width: min(100% - 20px, 1180px); padding-top: 16px; }
  .overview-top { display: block; }
  .exercise-text { font-size: 16px; }
}

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