:root {
  --teal-900: #0b3b36;
  --teal-800: #10504a;
  --teal-700: #14675f;
  --teal-600: #1b7f74;
  --teal-100: #dbf2ed;
  --teal-050: #edf9f6;
  --surface: #ffffff;
  --text-main: #12312c;
  --text-soft: #487069;
  --shadow: 0 10px 25px rgba(11, 59, 54, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Outfit", sans-serif;
  color: var(--text-main);
  background:
    radial-gradient(circle at 10% 20%, rgba(27, 127, 116, 0.2), transparent 30%),
    radial-gradient(circle at 90% 15%, rgba(20, 103, 95, 0.15), transparent 35%),
    linear-gradient(160deg, var(--teal-050), #f7fffc 45%, #f0fbf8 100%);
  display: grid;
  grid-template-rows: 1fr auto;
}

.page-shell {
  width: min(1080px, 92vw);
  margin: 2.5rem auto;
}

.hero {
  background: linear-gradient(135deg, var(--teal-900), var(--teal-700));
  color: #f7fffd;
  border-radius: 1.1rem;
  padding: 2rem;
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 0.76rem;
  opacity: 0.85;
}

.hero h1 {
  margin: 0.4rem 0 0.35rem;
  font-size: clamp(1.8rem, 3.3vw, 2.7rem);
}

.subtitle {
  margin: 0;
  color: rgba(247, 255, 253, 0.92);
}

.content {
  margin-top: 1.25rem;
  display: grid;
  grid-template-columns: minmax(200px, 290px) 1fr;
  gap: 1rem;
}

.panel {
  background: var(--surface);
  border: 1px solid #d2ebe5;
  border-radius: 1rem;
  padding: 1rem;
  box-shadow: 0 4px 12px rgba(9, 59, 54, 0.06);
}

.panel h2 {
  margin: 0 0 0.8rem;
  font-size: 1.1rem;
}

.panel-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.6rem;
}

.panel-header h2 {
  margin: 0;
}

.sheet-count {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.92rem;
}

.subject-list {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.subject-btn {
  border: 1px solid #bfddd6;
  background: #f9fffd;
  color: var(--teal-900);
  border-radius: 0.75rem;
  padding: 0.68rem 0.75rem;
  text-align: left;
  font: inherit;
  cursor: pointer;
  transition: background-color 0.2s ease, border-color 0.2s ease;
}

.subject-btn:hover {
  border-color: #94cbbf;
  background: var(--teal-050);
}

.subject-btn.active {
  background: var(--teal-100);
  border-color: var(--teal-600);
}

.sheet-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 0.7rem;
}

.sheet-card {
  border: 1px solid #d0e7e1;
  border-radius: 0.82rem;
  padding: 0.8rem;
  background: #ffffff;
  animation: fade-in 0.24s ease;
}

.sheet-name {
  margin: 0;
  font-size: 1rem;
}

.sheet-meta {
  margin: 0.35rem 0 0.8rem;
  color: var(--text-soft);
  font-size: 0.9rem;
}

.download-btn {
  display: inline-block;
  background: var(--teal-700);
  color: #ffffff;
  text-decoration: none;
  border-radius: 0.62rem;
  padding: 0.45rem 0.7rem;
  font-weight: 500;
  transition: background-color 0.2s ease;
}

.download-btn:hover {
  background: var(--teal-800);
}

.empty {
  margin: 0;
  color: var(--text-soft);
}

.site-footer {
  text-align: center;
  padding: 1.2rem;
  color: #2f5e56;
  font-size: 0.94rem;
}

@keyframes fade-in {
  from {
    opacity: 0;
    transform: translateY(4px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 760px) {
  .page-shell {
    margin: 1.25rem auto;
  }

  .hero {
    padding: 1.25rem;
  }

  .content {
    grid-template-columns: 1fr;
  }
}