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

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-color: #f1f5f9;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --success-color: #10b981;
    --accent-color: #f59e0b;
}

/* Light theme */
@media (prefers-color-scheme: light) {
    :root {
        --primary-color: #4f46e5;
        --primary-hover: #4338ca;
        --bg-color: #f8fafc;
        --card-bg: #ffffff;
        --text-color: #1e293b;
        --text-muted: #64748b;
        --border-color: #e2e8f0;
    }
}

/* Manual theme toggle */
:root[data-theme="light"] {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
}

:root[data-theme="dark"] {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-color: #f1f5f9;
    --text-muted: #94a3b8;
    --border-color: #334155;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Form Styles */
.settings-form {
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 1rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    max-width: 500px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.form-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: var(--card-bg);
    color: var(--text-color);
    cursor: pointer;
    transition: border-color 0.2s, box-shadow 0.2s;
}

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

.btn-primary {
    width: 100%;
    padding: 1rem 2rem;
    font-size: 1.1rem;
    font-weight: 600;
    color: white;
    background-color: var(--primary-color);
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

.btn-primary:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

/* Reader Styles */
.reader-container {
    max-width: 1400px;
}

.reader-container header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 2rem;
    text-align: left;
}

.reader-container header h1 {
    font-size: 1.5rem;
}

.back-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.back-link:hover {
    color: var(--primary-hover);
}

.reading-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.badge {
    background-color: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
}

.badge.level {
    background-color: var(--accent-color);
}

/* Hint */
.hint {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    padding: 0.75rem 1rem;
    background: var(--card-bg);
    border-radius: 0.5rem;
    border-left: 3px solid var(--primary-color);
}

/* Columns */
.columns-header {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 1rem;
    padding: 0 1rem;
}

.column-title {
    font-weight: 600;
    color: var(--text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.text-columns {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.paragraph-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    background: var(--card-bg);
    border-radius: 0.75rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

.original-column,
.translation-column {
    padding: 1.5rem;
}

.original-column {
    border-right: 1px solid var(--border-color);
}

.original-text {
    font-size: 1.1rem;
    line-height: 1.8;
}

.sentence {
    cursor: pointer;
    padding: 0.1rem 0.2rem;
    border-radius: 0.25rem;
    transition: background-color 0.2s, color 0.2s;
}

.sentence:hover {
    background-color: rgba(79, 70, 229, 0.1);
}

.sentence.speaking {
    background-color: var(--primary-color);
    color: white;
}

/* Translation */
.translation-wrapper {
    position: relative;
    cursor: pointer;
    min-height: 3rem;
}

.translation-text {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-color);
    transition: opacity 0.3s;
}

.translation-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 0.5rem;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
}

.translation-overlay span {
    color: var(--text-muted);
    font-weight: 500;
}

.translation-wrapper.hidden .translation-text {
    opacity: 0;
}

.translation-wrapper.hidden .translation-overlay {
    opacity: 1;
    pointer-events: auto;
}

/* Generate Again Form */
.generate-again-form {
    margin-top: 2rem;
    text-align: center;
}

.btn-generate-new {
    max-width: 300px;
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.5rem;
    cursor: pointer;
    font-size: 1.25rem;
    line-height: 1;
    transition: background-color 0.2s, transform 0.1s;
    z-index: 100;
}

.theme-toggle:hover {
    background: var(--border-color);
    transform: scale(1.05);
}

/* Footer */
footer {
    text-align: center;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    header h1 {
        font-size: 1.75rem;
    }
    
    .settings-form {
        padding: 1.5rem;
    }
    
    .paragraph-row {
        grid-template-columns: 1fr;
    }
    
    .original-column {
        border-right: none;
        border-bottom: 1px solid var(--border-color);
    }
    
    .columns-header {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }
    
    .columns-header .column-title:last-child {
        display: none;
    }
    
    .reader-container header {
        flex-wrap: wrap;
        gap: 1rem;
    }
}