* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #6b7280;
    --secondary-hover: #4b5563;
    --background-color: #f9fafb;
    --card-background: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --error-color: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --radius: 12px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    text-align: center;
    padding: 40px 0 30px;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 8px;
}

header .subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

main {
    flex: 1;
    position: relative;
}

/* Upload Section */
.upload-section {
    background: var(--card-background);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 40px 20px;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius);
    padding: 60px 20px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
}

.upload-area:hover,
.upload-area.drag-over {
    border-color: var(--primary-color);
    background-color: rgba(79, 70, 229, 0.05);
}

.upload-icon {
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-text {
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.upload-subtext {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.upload-button {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 12px 24px;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.upload-button:hover {
    background-color: var(--primary-hover);
}

/* Editor Section */
.editor-section {
    background: var(--card-background);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 24px;
}

.file-info {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px;
    background-color: var(--background-color);
    border-radius: 8px;
    margin-bottom: 24px;
}

.file-icon {
    color: var(--primary-color);
    flex-shrink: 0;
}

.file-name {
    flex: 1;
    font-weight: 500;
    word-break: break-all;
}

.change-file-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    border-radius: 6px;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.change-file-btn:hover {
    background-color: var(--border-color);
    color: var(--text-primary);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    background-color: var(--card-background);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.form-group input::placeholder {
    color: var(--text-secondary);
}

.form-actions {
    display: flex;
    gap: 12px;
    margin-top: 32px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
}

.btn-primary {
    flex: 1;
    background-color: var(--primary-color);
    color: white;
}

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

.btn-secondary {
    background-color: var(--background-color);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--border-color);
    color: var(--text-primary);
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(255, 255, 255, 0.9);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 16px;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.loading-overlay p {
    color: var(--text-secondary);
    font-weight: 500;
}

/* Footer */
footer {
    text-align: center;
    padding: 30px 0 20px;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Mobile Responsive */
@media (max-width: 640px) {
    .container {
        padding: 16px;
    }

    header {
        padding: 24px 0 20px;
    }

    header h1 {
        font-size: 1.5rem;
    }

    header .subtitle {
        font-size: 0.875rem;
    }

    .upload-section {
        padding: 24px 16px;
    }

    .upload-area {
        padding: 40px 16px;
    }

    .upload-icon svg {
        width: 48px;
        height: 48px;
    }

    .upload-text {
        font-size: 1rem;
    }

    .editor-section {
        padding: 20px 16px;
    }

    .file-info {
        padding: 12px;
    }

    .file-name {
        font-size: 0.875rem;
    }

    .form-group input {
        padding: 10px 14px;
        font-size: 0.9375rem;
    }

    .form-actions {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        padding: 14px 20px;
    }

    .btn-secondary {
        order: 1;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --background-color: #111827;
        --card-background: #1f2937;
        --text-primary: #f9fafb;
        --text-secondary: #9ca3af;
        --border-color: #374151;
    }

    .loading-overlay {
        background-color: rgba(17, 24, 39, 0.9);
    }

    .form-group input {
        color: var(--text-primary);
    }
}