/* ===== Base ===== */
:root {
  --brazil-a: #00a859;
  --brazil-b: #ffcb05;
  --usa-a: #b22234;
  --usa-b: #3c3b6e;
  --canada-a: #d52b1e;
  --canada-b: #ffffff;

  --card-bg: rgba(255, 255, 255, 0.8);
  --card-brd: rgba(0, 0, 0, 0.08);
  --text: #1a1a1a;
  --muted: #6b7280;
  --error: #b22234;
  --focus: #4b0082;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body { margin: 0; font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif; color: var(--text); }

/* ===== App (block) ===== */
.app {
  display: grid;
  place-items: center;
  min-height: 100%;
  padding: 1rem;
}

.app--bg { background: linear-gradient(135deg, var(--brazil-a), var(--brazil-b)); transition: background .25s ease; }
.app--bg--usa    { background: linear-gradient(135deg, var(--usa-a), var(--usa-b)); }
.app--bg--canada { background: linear-gradient(135deg, var(--canada-a), var(--canada-b)); }
.app--bg--brazil { background: linear-gradient(135deg, var(--brazil-a), var(--brazil-b)); }

.app__card {
  width: 100%;
  max-width: 640px;
  background: var(--card-bg);
  backdrop-filter: blur(8px);
  border: 1px solid var(--card-brd);
  border-radius: 12px;
  padding: 1.25rem;
  box-shadow: 0 6px 28px rgba(0,0,0,.12);
}

.app__title { margin: 0 0 .25rem; font-size: 1.5rem; font-weight: 700; text-align: center; }
.app__subtitle { margin: 0 0 1rem; text-align: center; color: var(--muted); }

/* ===== Form (block) ===== */
.form { display: grid; gap: .75rem; }

/* ===== Field (block) ===== */
.field { display: grid; gap: .35rem; }
.field--hidden { display: none; }

.field__label { font-weight: 600; }
.field__input {
  width: 100%;
  border: 2px solid #d1d5db;
  border-radius: 8px;
  padding: .625rem .75rem;
  background: rgba(255,255,255,.6);
}
.field__input:focus {
  outline: none;
  border-color: var(--focus);
  box-shadow: 0 0 0 3px rgba(75,0,130,.15);
}
.field__input--error { border-color: var(--error); }
.field__error { color: var(--error); font-size: .875rem; min-height: 1.2em; }

/* ===== Button (block) ===== */
.btn {
  display: inline-block;
  width: 100%;
  padding: .75rem .9rem;
  border: 0;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
}
.btn--primary { background: #111827; color: #fff; }
.btn--primary:hover { filter: brightness(1.05); }

/* ===== Result (block) ===== */
.result { margin-top: 1rem; }
.result__text { font-size: 1.05rem; font-weight: 600; }
.result__note { color: var(--muted); font-size: .9rem; }

/* ===== Utils ===== */
.visually-hidden { 
  position: absolute !important;
  height: 1px; width: 1px;
  overflow: hidden;
  clip: rect(1px, 1px, 1px, 1px);
  white-space: nowrap;
}