/* === ОБЩИЕ СТИЛИ === */
body {
  font-family: "Segoe UI", Tahoma, sans-serif;
  line-height: 1.7;
  background: #f7f9fc;
  color: #2c3e50;
  margin: 0;
  padding: 0;
}

/* === ШАПКА === */
header {
  background: linear-gradient(90deg, #ff8c00, #1e90ff);
  color: #fff;
  padding: 1rem 2rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  height: 90px;
  width: auto;
  border-radius: 6px;
}

.header-title {
  text-align: center;
  flex: 1;
}

header h1 {
  margin: 0;
  font-size: 1.9rem;
  font-weight: 700;
}

.subtitle {
  font-size: 1.1rem;
  margin-top: 5px;
  opacity: 0.9;
}

/* === ОСНОВНОЙ КОНТЕНТ === */
main {
  max-width: 950px;
  margin: 2rem auto;
  padding: 0 1.5rem;
}

h2 {
  border-left: 5px solid #1e90ff;
  padding-left: 10px;
  color: #1e3a8a;
  margin-top: 2rem;
  font-size: 1.6rem;
}

h3 {
  margin-top: 1.2rem;
  color: #2563eb;
  font-size: 1.2rem;
}

p {
  margin: 0.6rem 0;
}

/* === КОДОВЫЕ БЛОКИ === */
pre {
  background: #2d2d2d;
  color: #f8f8f2;
  padding: 1rem;
  border-radius: 10px;
  overflow-x: auto;
  margin: 1rem 0;
  font-size: 0.95rem;
}

p code, li code {
  background: rgba(0, 0, 0, 0.05);
  color: #c7254e;
  padding: 2px 6px;
  border-radius: 4px;
  font-family: "Consolas", monospace;
}

pre code {
  background: transparent;
  color: inherit;
  padding: 0;
}

/* === ВОПРОСЫ И ТЕСТ === */
#test {
  margin-top: 2rem;
}

.question {
  background: #fff;
  padding: 1rem 1.2rem;
  margin: 1rem 0;
  border-radius: 12px;
  box-shadow: 0 3px 10px rgba(0,0,0,0.08);
  transition: 0.3s ease;
}

.question:hover {
  transform: translateY(-2px);
}

.question p {
  font-weight: 600;
  color: #1e293b;
}

label {
  display: block;
  margin: 0.4rem 0;
  cursor: pointer;
  padding: 0.2rem 0.4rem;
  border-radius: 6px;
  transition: background 0.2s;
}

label:hover {
  background: #f1f5f9;
}

/* === КНОПКА === */
#submitBtn {
  display: block;
  margin: 2rem auto 1rem auto;
  padding: 0.9rem 2.5rem;
  background: linear-gradient(90deg, #27ae60, #219150);
  color: white;
  font-size: 1.15rem;
  font-weight: bold;
  border: none;
  border-radius: 40px;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.3s;
}

#submitBtn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 10px rgba(39,174,96,0.3);
}

/* === РЕЗУЛЬТАТ === */
#result {
  text-align: center;
  font-size: 1.2rem;
  margin-top: 1.5rem;
  font-weight: 600;
}

/* === ПОДСВЕТКА === */
.correct {
  background-color: #e7f9ee;
  border-left: 5px solid #27ae60;
}

.incorrect {
  background-color: #ffebee;
  border-left: 5px solid #e74c3c;
}

.correct-answer {
  background-color: #d1fae5;
  border-left: 5px solid #10b981;
}

.incorrect-answer {
  background-color: #fee2e2;
  border-left: 5px solid #ef4444;
}

/* === ДОМАШКА === */
#homework {
  margin-top: 2.5rem;
  background: #ffffff;
  padding: 1.2rem 1.5rem;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

#homework ol {
  padding-left: 1.4rem;
}

#homework li {
  margin: 0.6rem 0;
}

/* === ПОДВАЛ === */
footer {
  text-align: center;
  padding: 1rem;
  margin-top: 2rem;
  background: #f1f5f9;
  color: #475569;
  font-size: 0.95rem;
  border-top: 2px solid #e2e8f0;
}