:root {
  --bg-color: #F5F5F0;
  --text-color: #333333;
  --header-color: #4B4A47;
  --card-bg: #EDECE8;
  --accent-color: #7C6D62;
  --border-color: #D8D6CD;
  --watermark-color: #A9A79E;
}

[data-theme="dark"] {
  --bg-color: #2C2C2C;
  --text-color: #E0E0E0;
  --header-color: #1F1F1F;
  --card-bg: #3A3A3A;
  --accent-color: #B8A68F;
  --border-color: #444444;
  --watermark-color: #888888;
}

/* 📱 Base = Mobile styles */
body {
  font-family: 'Noto Sans', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  font-size: 1rem;
  margin: 0;
  padding: 0;
  padding-top: 3.5rem;
}

header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background-color: var(--header-color);
  color: var(--bg-color);
  text-align: center;
  padding: 0.4rem;
  box-shadow: 0 0.2rem 0.5rem rgba(0,0,0,0.08);
  z-index: 999;
  font-size: 1.6rem;
}

.day-block {
  background-color: #fff;
  border: 0.1rem solid var(--border-color);
  padding: 0.8rem;
  border-radius: 0.6rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 0.2rem 0.4rem rgba(0, 0, 0, 0.04);
}

#date-selection {
  margin: 1.5rem auto;
  padding: 1rem;
  max-width: 95%;
  background-color: var(--card-bg);
  border-radius: 0.5rem;
  box-shadow: 0 0.1rem 0.3rem rgba(0,0,0,0.08);
}

#date-selection h2 {
  margin-top: 0;
  color: var(--accent-color);
  font-size: 1.2rem;
}

#date-form label {
  display: block;
  margin-bottom: 0.4rem;
  font-size: 0.8rem;
}

#date-form input[type="date"] {
  padding: 0.4rem;
  font-size: 1.2rem;
  border: 0.1rem solid var(--border-color);
  border-radius: 0.3rem;
  background-color: white;
  width: 100%;
}

#date-form button {
  margin-top: 1rem;
  padding: 0.6rem 1.2rem;
  background-color: var(--accent-color);
  color: white;
  border: none;
  border-radius: 0.3rem;
  font-weight: bold;
  cursor: pointer;
  width: 100%;
  font-size: 1rem;
}

#homework {
  max-width: 95%;
  margin: 1.5rem auto;
  padding: 0.8rem;
  font-size: 1rem;
}

#homework h3 {
  background-color: var(--accent-color);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 0.4rem;
  margin-top: 0;
  margin-bottom: 1rem;
  font-weight: 500;
  font-size: 1.4rem;
}

#homework h4 {
  margin-bottom: 0.5rem;
  color: var(--header-color);
}

#homework ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

#homework li {
  background-color: var(--card-bg);
  border-left: 0.3rem solid var(--accent-color);
  padding: 1rem;
  margin-bottom: 1rem;
  border-radius: 0.4rem;
  box-shadow: 0 0.1rem 0.2rem rgba(0,0,0,0.04);
  position: relative;
}

#ExInfo {
  font-size: 0.8rem;
  color: var(--text-color);
  margin-top: 0.2rem;
}

.watermark {
  position: absolute;
  right: 0.8rem;
  bottom: 0.4rem;
  font-size: 0.6rem;
  color: var(--watermark-color);
  opacity: 0.6;
  pointer-events: none;
}

/* 💻 Tablet and up */
@media screen and (min-width: 769px) {
  body {
    font-size: 1.5rem;
  }

  header {
    font-size: 4rem;
    padding: 0rem;
  }

  #date-selection,
  #homework {
    max-width: 90%;
    padding: 1rem;
    font-size: 2.5rem;
  }

  #date-form button {
    font-size: 1.1rem;
  }

  #homework h3 {
    font-size: 2rem;
  }

  #date-selection h2 {
    font-size: 1.4rem;
  }

  #date-form label {
    font-size: 0.9rem;
  }

  #date-form input[type="date"] {
    font-size: 1.2rem;
  }

  #ExInfo {
    font-size: 1.2rem;
  }
}

/* 🖥️ Desktop large screens */
@media screen and (min-width: 1200px) {
  header {
    font-size: 2rem;
  }

  #date-selection,
  #homework {
    max-width: 70%;
    font-size: 1.3rem;
  }

  #homework h3 {
    font-size: 1.5rem;
  }

  #date-selection h2 {
    font-size: 1.5rem;
  }
}