html, body {
  height: 100%;
  width: 100%;
  margin: 0;
  font-family: 'Inter', sans-serif; /* Changed to Inter as per instructions */
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #f0f2f5; /* Light grey background */
  padding: 20px; /* Add padding for small screens */
  box-sizing: border-box; /* Include padding in element's total width and height */
}

.container {
  text-align: center;
  background-color: #ffffff;
  padding: 30px;
  border-radius: 15px; /* Slightly more rounded */
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1); /* Stronger shadow */
  max-width: 500px; /* Adjusted max-width for better balance */
  width: 100%; /* Ensure it takes full width on small screens */
  display: flex; /* Use flexbox for internal layout */
  flex-direction: column; /* Stack children vertically */
  align-items: center; /* Center items horizontally */
}

h1 {
  color: #333;
  margin-bottom: 25px;
  font-size: 1.8em; /* Adjusted font size */
}

/* Message display styling */
.message {
    padding: 10px;
    margin-bottom: 15px; /* Margin below message */
    border-radius: 8px;
    text-align: center;
    font-weight: bold;
    color: #333;
    background-color: #e0f7fa; /* Light blue for info */
    border: 1px solid #b2ebf2;
    width: 100%; /* Ensure it takes full width */
    box-sizing: border-box; /* Include padding in width */

    /* NEW: Fixed height and visibility control */
    min-height: 45px; /* Adjust this height based on your typical message length */
    opacity: 0; /* Initially hidden */
    visibility: hidden; /* Keeps space but makes it unclickable */
    transition: opacity 0.5s ease-in-out; /* Smooth fade effect */
    display: flex; /* Use flex to center text vertically */
    align-items: center;
    justify-content: center;
}
.message.success {
    background-color: #e8f5e9; /* Light green for success */
    border-color: #c8e6c9;
    color: #2e7d32;
}
.message.error {
    background-color: #ffebee; /* Light red for error */
    border-color: #ffcdd2;
    color: #c62828;
}


.card {
  background-color: #eef; /* Lighter background for card */
  border: 1px solid #ddd;
  border-radius: 12px; /* More rounded corners */
  padding: 30px;
  min-height: 150px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  margin-bottom: 25px; /* Adjusted margin */
  box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.05); /* Subtle inner shadow */
  width: 100%; /* Ensure it takes full width */
  box-sizing: border-box;
}

#flashcard-text {
  font-size: 1.4em; /* Adjusted font size */
  font-weight: bold;
  color: #555;
  margin: 0 0 15px 0; /* Adjust margin */
  text-align: center;
}

#flashcard-answer {
  font-size: 1.2em;
  color: #007bff; /* Blue color for answer */
  margin: 0;
  text-align: center;
  font-style: italic;
}

.controls {
  margin-top: 20px;
  margin-bottom: 25px; /* Added margin below controls before progress bar */
  display: flex;
  flex-wrap: wrap; /* Allow buttons to wrap on smaller screens */
  justify-content: center;
  gap: 10px; /* Space between buttons */
  width: 100%; /* Ensure controls take full width */
}

button {
  padding: 12px 20px;
  font-size: 1em;
  border: none;
  border-radius: 8px; /* More rounded buttons */
  cursor: pointer;
  transition: background-color 0.3s ease, transform 0.1s ease, box-shadow 0.3s ease;
  background-color: #007bff; /* Primary button color */
  color: white;
  box-shadow: 0 4px 8px rgba(0, 123, 255, 0.2); /* Subtle shadow */
}

button:hover {
  background-color: #0056b3; /* Darker blue on hover */
  transform: translateY(-2px); /* Slight lift effect */
  box-shadow: 0 6px 12px rgba(0, 123, 255, 0.3);
}

button:disabled {
  background-color: #cccccc;
  cursor: not-allowed;
  box-shadow: none;
  transform: translateY(0);
}

/* Specific style for "Mark as Wrong" button */
button[onclick="markAsWrong()"] {
  background-color: #dc3545; /* Red for wrong */
  box-shadow: 0 4px 8px rgba(220, 53, 69, 0.2);
}

button[onclick="markAsWrong()"]:hover {
  background-color: #c82333;
  box-shadow: 0 6px 12px rgba(220, 53, 69, 0.3);
}

/* Specific style for "Review Marked Questions" button */
button[onclick="startWrongOnlyQuiz()"] {
  background-color: #ffc107; /* Yellow for review */
  color: #333;
  box-shadow: 0 4px 8px rgba(255, 193, 7, 0.2);
}

button[onclick="startWrongOnlyQuiz()"]:hover {
  background-color: #e0a800;
  box-shadow: 0 6px 12px rgba(255, 193, 7, 0.3);
}

/* Progress Bar Styling */
.progress-section {
    width: 100%;
    margin-top: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.progress-bar-container {
    width: 100%;
    height: 20px;
    background-color: #e0f2f7; /* Light blue for the empty part */
    border-radius: 10px;
    overflow: hidden; /* Ensures the fill stays within the rounded corners */
    margin-bottom: 10px;
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1);
}

.progress-bar-fill {
    height: 100%;
    width: 0%; /* Initial width, controlled by JS */
    background-color: #007bff; /* Dark blue for the filled part */
    border-radius: 10px; /* Match container radius */
    transition: width 0.4s ease-in-out; /* Smooth transition for progress */
}

.progress-text {
    font-size: 1em;
    color: #555;
    font-weight: bold;
}

/* Responsive adjustments for buttons */
@media (max-width: 480px) {
    .controls button {
        width: calc(100% - 20px); /* Full width minus gap */
        margin: 5px 0; /* Adjust margin for stacking */
    }
}