:root {
    --exercise-font-family: Arial, sans-serif;
    --exercise-font-mono: 'Courier New', monospace;
    --exercise-border-color: #ccc;
    --exercise-border-radius: 4px;
    --exercise-padding-std: 10px;
    --exercise-padding-sm: 5px;
    --exercise-padding-lg: 20px;
    --exercise-gap: 20px;
    --exercise-bg-output: #f9f9f9;
    --exercise-bg-answer: #f8f8f8;
    --exercise-bg-line-numbers: #f5f5f5;
    --exercise-primary-color: #007cba;
    --exercise-primary-hover: #005a87;
    --exercise-secondary-color: #f39c12;
    --exercise-secondary-hover: #d68910;
    --exercise-success-color: #e8f5e8;
    --exercise-success-border: green;
    --exercise-error-color: #ffeaea;
    --exercise-error-border: red;
    --exercise-disabled-bg: #ccc;
    --exercise-text-muted: #666;
    --exercise-border-line-numbers: #ddd;
    --exercise-font-size: 14px;
    --exercise-font-size-lg: 16px;
    --exercise-font-size-xl: 24px;
    --exercise-height-editor: 250px; /* Reduced from 300px */
    --exercise-line-height: 1.4; /* Slightly reduced */
    --exercise-min-width-line-numbers: 35px; /* Reduced from 40px */
}

body {
    font-family: var(--exercise-font-family);
    margin: 0 auto;
    padding: var(--exercise-padding-lg);
}

.exercise-container {
    border: 1px solid var(--exercise-border-color);
    border-radius: var(--exercise-border-radius);
    background: #f9f9ff;
    padding: var(--exercise-padding-std);
    margin-bottom: var(--exercise-gap);
    display: flex;
    flex-direction: column;
    gap: var(--exercise-gap);
    width: 100%;
    box-sizing: border-box;
}

@media (min-width: 769px) {
    .exercise-container {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: var(--exercise-gap);
    }
}

.editor-section {
    position: relative;
    width: 100%;
    min-width: 0; /* Allow flex children to shrink */
}

.editor {
    position: relative;
    width: 100%;
    height: var(--exercise-height-editor);
    border: 2px solid var(--exercise-border-color);
    border-radius: var(--exercise-border-radius);
    font-family: var(--exercise-font-mono);
    font-size: var(--exercise-font-size);
    min-height: var(--exercise-height-editor);
    padding: var(--exercise-padding-std);
    resize: vertical;
    margin: 0;
    overflow: auto;
    box-sizing: border-box;
    max-width: 100%;
}

.with-line-numbers {
    display: flex;
}

.line-numbers {
    background-color: var(--exercise-bg-line-numbers);
    border-right: 1px solid var(--exercise-border-line-numbers);
    color: var(--exercise-text-muted);
    font-family: var(--exercise-font-mono);
    font-size: var(--exercise-font-size);
    line-height: var(--exercise-line-height);
    padding: var(--exercise-padding-std) 8px;
    text-align: right;
    user-select: none;
    min-width: var(--exercise-min-width-line-numbers);
}

.line-numbers span {
    display: block;
}

.editor > code {
    padding: var(--exercise-padding-std);
    outline: none;
    flex: 1;
    overflow-x: auto;
    white-space: pre-wrap;
    overflow-wrap: break-word;
    display: block;
    width: 100%;
    box-sizing: border-box;
}

.output-section {
    display: flex;
    flex-direction: column;
    width: 100%;
    min-width: 0;
}

.output {
    width: 100%;
    height: var(--exercise-height-editor);
    border: 2px solid var(--exercise-border-color);
    border-radius: var(--exercise-border-radius);
    padding: var(--exercise-padding-std);
    background-color: var(--exercise-bg-output);
    font-family: var(--exercise-font-mono);
    font-size: var(--exercise-font-size);
    overflow-y: auto;
    white-space: pre-wrap;
    box-sizing: border-box;
    margin: 0;
}

.controls {
    margin: var(--exercise-padding-std) 0;
}

.run-btn {
    background-color: var(--exercise-primary-color);
    color: white;
    border: none;
    padding: var(--exercise-padding-std) var(--exercise-padding-lg);
    border-radius: var(--exercise-border-radius);
    cursor: pointer;
    font-size: var(--exercise-font-size-lg);
}

.run-btn:hover {
    background-color: var(--exercise-primary-hover);
}

.run-btn:disabled {
    background-color: var(--exercise-disabled-bg);
    cursor: not-allowed;
}

.reveal-answer-btn {
    background-color: var(--exercise-secondary-color);
    color: white;
    border: none;
    padding: var(--exercise-padding-std) var(--exercise-padding-lg);
    border-radius: var(--exercise-border-radius);
    cursor: pointer;
    font-size: var(--exercise-font-size-lg);
    margin-left: var(--exercise-padding-std);
}

.reveal-answer-btn:hover {
    background-color: var(--exercise-secondary-hover);
}

.reveal-answer-btn:disabled {
    background-color: var(--exercise-disabled-bg);
    cursor: not-allowed;
}

.checkmark {
    display: none;
    color: var(--exercise-success-border);
    font-size: var(--exercise-font-size-xl);
    margin-left: var(--exercise-padding-std);
}

.correct {
    border-color: var(--exercise-success-border) !important;
    background-color: var(--exercise-success-color) !important;
}

.incorrect {
    border-color: var(--exercise-error-border) !important;
    background-color: var(--exercise-error-color) !important;
}

.answer {
    margin-top: var(--exercise-padding-std);
    padding: var(--exercise-padding-sm); /* Reduced padding */
    border-radius: var(--exercise-border-radius);
    font-family: var(--exercise-font-mono);
    white-space: pre-wrap;
    display: none;
    border: 1px solid var(--exercise-border-line-numbers);
    position: relative;
}

.answer pre {
    margin: 0;
    padding: 0;
    background: transparent;
    border: none;
    font-family: inherit;
    font-size: inherit;
}

.answer code {
    font-family: inherit;
    font-size: inherit;
    background: transparent;
    padding: 0;
}

.answer.language-python {
    background: var(--exercise-bg-answer);
}

.answer.show-solution {
    border: 2px solid var(--exercise-secondary-color) !important;
    background: #f8fff8 !important;
    width: 100%;
    box-sizing: border-box;
    display: block !important;
}

.answer.show-solution::before {
    content: "Solution:";
    display: block;
    font-weight: bold;
    color: var(--exercise-secondary-color);
    margin-bottom: var(--exercise-padding-sm);
    font-family: var(--exercise-font-family);
    font-size: var(--exercise-font-size-lg);
}

/* Mobile-specific optimizations */
@media (max-width: 768px) {
    :root {
        --exercise-height-editor: 200px; /* Further reduced for mobile */
        --exercise-gap: 15px; /* Reduced gap */
        --exercise-padding-std: 8px; /* Reduced padding */
        --exercise-padding-lg: 15px; /* Reduced large padding */
    }

    .exercise-container {
        padding: var(--exercise-padding-std);
        margin-bottom: var(--exercise-gap);
    }

    .editor, .output {
        height: var(--exercise-height-editor);
        min-height: var(--exercise-height-editor);
        padding: var(--exercise-padding-std);
    }

    .controls {
        margin: var(--exercise-padding-sm) 0; /* Reduced margin */
    }

    .run-btn, .reveal-answer-btn {
        padding: var(--exercise-padding-sm) var(--exercise-padding-std); /* Smaller buttons */
        font-size: var(--exercise-font-size); /* Smaller text */
    }

    .answer {
        padding: var(--exercise-padding-sm);
        margin-top: var(--exercise-padding-sm);
    }
}

/* Very small screens */
@media (max-width: 480px) {
    :root {
        --exercise-height-editor: 180px; /* Even smaller for very small screens */
        --exercise-gap: 10px;
        --exercise-padding-std: 6px;
    }

    .exercise-container {
        padding: var(--exercise-padding-sm);
    }

    .run-btn, .reveal-answer-btn {
        width: 100%; /* Full width buttons on very small screens */
        margin: var(--exercise-padding-sm) 0;
    }

    .controls {
        display: flex;
        flex-direction: column;
        gap: var(--exercise-padding-sm);
    }

    .checkmark {
        align-self: flex-start;
        margin-left: 0;
        margin-top: var(--exercise-padding-sm);
    }
}