@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;600;700&display=swap');

/* Variables de color */
:root {
  --color-primary: #1b2a49;     /* Azul marino oscuro */
  --color-secondary: #274472;   /* Azul medio */
  --color-accent: #4a90e2;      /* Azul vibrante */
  --color-bg-light: #e6f0fa;    /* Azul muy claro */
  --color-bg-dark: #162a4f;     /* Azul noche */
  --color-text-dark: #1b2a49;   /* Texto azul oscuro */
  --color-text-light: #f0f6ff;  /* Texto casi blanco */
  --border-radius: 20px;
  --shadow-light: rgba(38, 70, 130, 0.15);
  --shadow-heavy: rgba(0, 22, 54, 0.35);
  --transition-speed: 0.35s;
}

/* Reset y base */
*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  font-family: 'Poppins', sans-serif;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: var(--color-text-dark);
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding-bottom: 4rem;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Contenedor general */
.container {
  width: 90%;
  max-width: 1100px;
  margin: 3rem auto 6rem;
  background: var(--color-bg-light);
  border-radius: var(--border-radius);
  box-shadow: 0 16px 40px var(--shadow-heavy);
  padding: 3rem 4rem;
  position: relative;
  overflow: hidden;
  transition: box-shadow var(--transition-speed);
}

.container:hover {
  box-shadow: 0 20px 50px var(--shadow-heavy);
}

/* Header */
header {
  width: 100%;
  max-width: 1100px;
  text-align: center;
  margin-top: 2rem;
  color: var(--color-text-light);
  position: relative;
  z-index: 10;
}

header h1 {
  font-size: 3rem;
  letter-spacing: 2px;
  margin-bottom: 0.2rem;
  font-weight: 700;
  text-shadow: 2px 3px 10px rgba(0,0,0,0.4);
}

header p {
  font-size: 1.3rem;
  opacity: 0.85;
  font-weight: 400;
  letter-spacing: 0.06em;
}

/* Barra de progreso */
#progress-container {
  width: 100%;
  height: 30px;
  background: rgba(255, 255, 255, 0.15);
  border-radius: 50px;
  margin: 2rem auto 1.5rem;
  box-shadow: inset 0 3px 10px rgba(255,255,255,0.3);
  overflow: hidden;
  position: relative;
}

#progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--color-accent), var(--color-secondary));
  box-shadow: 0 0 20px var(--color-accent);
  border-radius: 50px;
  transition: width 0.6s ease-in-out;
}

#progress-text {
  text-align: center;
  font-weight: 600;
  color: var(--color-text-light);
  font-size: 1.2rem;
  letter-spacing: 0.07em;
  margin-top: 0.5rem;
  user-select: none;
  text-shadow: 1px 1px 3px rgba(0,0,0,0.4);
}

/* Grid de cursos */
.grid-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 2.5rem;
  margin-top: 1rem;
  width: 100%;
}

/* Botones de cursos */
.course-btn {
  background: white;
  color: var(--color-primary);
  padding: 2.4rem 1.8rem;
  font-size: 1.4rem;
  font-weight: 600;
  border-radius: var(--border-radius);
  text-align: center;
  text-decoration: none;
  box-shadow: 0 10px 28px var(--shadow-light);
  transition:
    transform var(--transition-speed) ease,
    background-color var(--transition-speed) ease,
    color var(--transition-speed) ease,
    box-shadow var(--transition-speed) ease;
  position: relative;
  overflow: hidden;
  user-select: none;
}

.course-btn::before {
  content: '';
  position: absolute;
  top: -40%;
  left: -40%;
  width: 180%;
  height: 180%;
  background: radial-gradient(circle, var(--color-accent) 0%, transparent 70%);
  opacity: 0;
  transition: opacity var(--transition-speed);
  pointer-events: none;
  border-radius: 50%;
  z-index: 0;
}

.course-btn:hover {
  background-color: var(--color-primary);
  color: var(--color-text-light);
  transform: translateY(-10px) scale(1.08);
  box-shadow: 0 14px 35px var(--shadow-heavy);
}

.course-btn:hover::before {
  opacity: 0.3;
}

/* Contenedor del curso */
.course-container {
  background: white;
  border-radius: var(--border-radius);
  padding: 3.5rem 4.5rem;
  margin: 2.5rem auto;
  max-width: 900px;
  box-shadow: 0 18px 50px var(--shadow-heavy);
  color: var(--color-text-dark);
  line-height: 1.7;
  position: relative;
  z-index: 5;
}

/* Títulos en el curso */
.course-container h2 {
  font-size: 2.4rem;
  margin-bottom: 1.5rem;
  color: var(--color-primary);
  border-bottom: 4px solid var(--color-accent);
  padding-bottom: 0.5rem;
  letter-spacing: 0.07em;
  font-weight: 700;
}

/* Secciones */
section {
  margin-bottom: 2.5rem;
  font-size: 1.22rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  color: #444;
}

/* Botón volver */
.back-btn {
  display: inline-block;
  padding: 0.9rem 1.8rem;
  background: var(--color-primary);
  color: var(--color-text-light);
  font-weight: 600;
  border-radius: 14px;
  text-decoration: none;
  box-shadow: 0 10px 30px rgba(27, 42, 73, 0.6);
  transition: background-color var(--transition-speed);
  user-select: none;
}

.back-btn:hover {
  background: var(--color-secondary);
  box-shadow: 0 12px 35px rgba(39, 68, 114, 0.8);
}

/* Quiz styling */
.quiz-form {
  max-width: 520px;
  margin-top: 2rem;
}

.quiz-question {
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--color-primary);
  margin-bottom: 1.4rem;
  letter-spacing: 0.07em;
  text-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.quiz-option {
  display: flex;
  align-items: center;
  background: #f4f8ff;
  border-radius: 16px;
  margin-bottom: 1.4rem;
  padding: 16px 22px;
  cursor: pointer;
  transition: background-color var(--transition-speed);
  user-select: none;
  border: 3px solid transparent;
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--color-primary);
}

.quiz-option:hover {
  background-color: var(--color-accent);
  color: var(--color-text-light);
  border-color: var(--color-accent);
  font-weight: 600;
}

.quiz-option input[type="radio"] {
  margin-right: 18px;
  accent-color: var(--color-primary);
  width: 26px;
  height: 26px;
  cursor: pointer;
}

/* Submit button */
.quiz-submit {
  width: 100%;
  background: var(--color-primary);
  color: var(--color-text-light);
  font-size: 1.25rem;
  font-weight: 700;
  padding: 16px 0;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  box-shadow: 0 12px 40px rgba(27, 42, 73, 0.75);
  transition: background-color var(--transition-speed);
  user-select: none;
}

.quiz-submit:hover {
  background: var(--color-secondary);
  box-shadow: 0 14px 48px rgba(39, 68, 114, 0.9);
}

/* Result message */
.quiz-result {
  margin-top: 2rem;
  font-weight: 700;
  font-size: 1.5rem;
  display: flex;
  align-items: center;
  gap: 14px;
  color: var(--color-primary);
  user-select: none;
}

.quiz-result.correct {
  color: #2e7d32;
}

.quiz-result.correct::before {
  content: "✔️";
  font-size: 2rem;
}

.quiz-result.incorrect {
  color: #d32f2f;
}

.quiz-result.incorrect::before {
  content: "❌";
  font-size: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
  .container {
    padding: 2rem 2.5rem;
  }

  header h1 {
    font-size: 2.2rem;
  }

  header p {
    font-size: 1rem;
  }

  .course-btn {
    font-size: 1.15rem;
    padding: 1.8rem 1.2rem;
  }

  .course-container {
    padding: 2rem 2.5rem;
    margin: 2rem 1rem 3rem;
  }

  .course-container h2 {
    font-size: 1.9rem;
  }

  .quiz-question {
    font-size: 1.25rem;
  }

  .quiz-submit {
    font-size: 1.1rem;
    padding: 14px 0;
  }
}

@media (max-width: 480px) {
  .grid-container {
    grid-template-columns: 1fr;
    gap: 1.8rem;
  }

  .course-btn {
    padding: 1.6rem 1rem;
    font-size: 1.1rem;
  }

  .container {
    padding: 1.8rem 1.8rem;
    margin: 1.5rem auto 2rem;
  }
}