:root {
  --color-bg: #0f1724;
  /* escuro de apoio */
  --color-surface: #111827;
  --color-primary: #1E3A8A;
  --color-accent: #34D399;
  --color-text: #D1D5DB;
  --container-max: 1100px;
  --radius: 12px;
  --gap: 1rem;
}

/* light theme overrides */
:root.light {
  --color-bg: #ffffff;
  --color-surface: #f9fafb;
  --color-text: #0f1724;
}

* {
  box-sizing: border-box
}

html,
body {
  height: 100%
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background-color: var(--color-bg);
  color: var(--color-text);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.5;
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 1rem;
}

.site-header {
  background: transparent;
  padding: 0.5rem 0
}

.nav {
  display: flex;
  align-items: center;
  gap: 1rem;
  justify-content: space-between
}

.nav__brand {
  font-weight: 700;
  color: var(--color-accent);
  text-decoration: none
}

.nav__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 0.75rem
}

.nav__list a {
  color: var(--color-text);
  text-decoration: none;
  padding: 0.25rem 0.5rem;
  border-radius: 6px
}

.btn {
  background: var(--color-primary);
  color: white;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  border: none;
  cursor: pointer;
}

.btn--outline {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.08);
  color: var(--color-text)
}

.btn--ghost {
  background: transparent;
  border: none;
  color: var(--color-text)
}

.btn--accent {
  background: var(--color-accent);
  color: #01220b
}

.music {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  align-items: center;
  padding: 2rem 0;
}

.music__media img {
  width: 100%;
  max-width: 800px;
  height: 450px;
  border-radius: 12px;
  display: block;

}

.music__title {
  font-size: clamp(1.6rem, 2.5vw, 2.2rem);
  margin: 0 0 0.5rem;
}

.music__desc {
  margin: 0 0 1rem;
  color: var(--color-text);
  opacity: 0.9;
  padding-bottom: 20px;
}

.exercise {
  background: var(--color-surface);
  padding: 1rem;
  border-radius: 8px;
  margin-bottom: 1rem
}

.exercise h2 {
  margin: 0 0 0.5rem
}

.exercise__form label {
  display: block;
  margin: 0.35rem 0;
  padding-left: 0.25rem
}

.exercise__actions {
  display: flex;
  gap: 1rem;
  align-items: center;
  margin-top: 0.75rem
}

.exercise__meta {
  margin-left: auto;
  color: var(--color-text);
  opacity: 0.9
}

.exercise__feedback {
  margin-top: 0.5rem;
  padding: 0.5rem;
  border-radius: 6px;
  min-height: 1.2rem
}

.exercise__form select {
  width: 100%;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  border: 1px solid rgba(255,255,255,0.2);
  background-color: var(--color-surface);
  color: var(--color-text);
  font-size: 1rem;
  cursor: pointer;
  transition: border 0.3s, box-shadow 0.3s;

  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;

  background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20width%3D'10'%20height%3D'5'%20viewBox%3D'0%200%2010%205'%20xmlns%3D'http://www.w3.org/2000/svg'%3E%3Cpath%20d%3D'M0%200l5%205%205-5z'%20fill%3D'%23D1D5DB'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  background-size: 10px 5px;
}

.exercise__form select:hover,
.exercise__form select:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 2px rgba(52,211,153,0.3);
  outline: none;
}

.sr-only {
  position: absolute !important;
  height: 1px;
  width: 1px;
  overflow: hidden;
  clip: rect(1px, 1px, 1px, 1px);
  white-space: nowrap
}

.score__box {
  display: flex;
  gap: 1rem;
  align-items: center;
  margin-top: 2rem
}

footer.site-footer {
  padding: 2rem 0;
  text-align: center;
  color: var(--color-text);
  opacity: 0.7
}

/* feedback colors */
.feedback-correct {
  background: linear-gradient(90deg, var(--color-accent), rgba(0, 0, 0, 0));
  color: #042007;
  padding: 0.5rem
}

.feedback-wrong {
  background: rgba(255, 0, 0, 0.06);
  color: #ffb3b3;
  padding: 0.5rem
}

/* responsive */
@media (max-width:900px) {
  .music {
    grid-template-columns: 1fr;
    padding: 1rem 0
  }

  .nav__list {
    display: none
  }

  .container {
    padding: 0.75rem
  }
}