/* CSS Variables */
:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #6366f1;
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --input-bg: #f1f5f9;
    --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-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --transition: all 0.2s ease;
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

/* Container */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 2rem;
}

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 0.5rem;
}

.logo {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

header h1 {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.025em;
}

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

/* Main Content */
main {
    flex: 1;
}

/* Mode Toggle */
.mode-toggle {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    background: var(--card-bg);
    padding: 0.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    width: fit-content;
    margin-left: auto;
    margin-right: auto;
}

.mode-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.mode-btn:hover {
    color: var(--text-primary);
    background: var(--input-bg);
}

.mode-btn.active {
    background: var(--primary-color);
    color: white;
}

/* Options Panel */
.options-panel {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.option-group {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.option-group label {
    font-weight: 500;
    color: var(--text-secondary);
}

/* Checkbox Styling */
.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    user-select: none;
}

.checkbox-label input[type="checkbox"] {
    display: none;
}

.checkmark {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.checkbox-label input[type="checkbox"]:checked + .checkmark {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.checkbox-label input[type="checkbox"]:checked + .checkmark::after {
    content: '';
    width: 6px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
    margin-bottom: 2px;
}

/* Select */
select {
    padding: 0.5rem 2rem 0.5rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--card-bg);
    color: var(--text-primary);
    font-size: 0.95rem;
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    transition: var(--transition);
}

select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgb(79 70 229 / 0.1);
}

.custom-delimiter {
    width: 100px;
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    transition: var(--transition);
}

.custom-delimiter:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgb(79 70 229 / 0.1);
}

.hidden {
    display: none !important;
}

/* Converter Area */
.converter-area {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 1.5rem;
    align-items: stretch;
}

/* Panel */
.panel {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
    background: var(--input-bg);
}

.panel-header h2 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.panel-actions {
    display: flex;
    gap: 0.5rem;
}

.action-btn {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.4rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--card-bg);
    color: var(--text-secondary);
    font-size: 0.85rem;
    cursor: pointer;
    transition: var(--transition);
}

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

.action-btn svg {
    flex-shrink: 0;
}

/* Textarea */
textarea {
    flex: 1;
    min-height: 350px;
    padding: 1rem;
    border: none;
    resize: vertical;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    color: var(--text-primary);
    background: var(--card-bg);
}

textarea:focus {
    outline: none;
}

textarea::placeholder {
    color: var(--text-secondary);
}

#outputArea {
    background: var(--input-bg);
}

/* File Upload */
.file-upload {
    padding: 1rem 1.25rem;
    border-top: 1px solid var(--border-color);
}

.file-upload input[type="file"] {
    display: none;
}

.file-label {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.file-label:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    background: rgb(79 70 229 / 0.05);
}

/* Convert Section */
.convert-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.convert-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-md);
}

.convert-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.convert-btn:active {
    transform: translateY(0);
}

.swap-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 50%;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.swap-btn:hover {
    background: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
}

/* Status Message */
.status-message {
    margin-top: 1.5rem;
    padding: 1rem 1.25rem;
    border-radius: var(--radius-md);
    text-align: center;
    font-weight: 500;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.status-message.success {
    background: rgb(16 185 129 / 0.1);
    color: var(--success-color);
    border: 1px solid rgb(16 185 129 / 0.2);
}

.status-message.error {
    background: rgb(239 68 68 / 0.1);
    color: var(--error-color);
    border: 1px solid rgb(239 68 68 / 0.2);
}

.status-message.info {
    background: rgb(99 102 241 / 0.1);
    color: var(--secondary-color);
    border: 1px solid rgb(99 102 241 / 0.2);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0 1rem;
    margin-top: auto;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

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

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

/* Responsive Design */
@media (max-width: 1024px) {
    .converter-area {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .convert-section {
        flex-direction: row;
        justify-content: center;
        padding: 0.5rem 0;
    }

    .convert-btn svg {
        transform: rotate(90deg);
    }
}

@media (max-width: 768px) {
    .container {
        padding: 1.5rem 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .logo {
        width: 40px;
        height: 40px;
    }

    .subtitle {
        font-size: 1rem;
    }

    .mode-toggle {
        width: 100%;
        justify-content: stretch;
    }

    .mode-btn {
        flex: 1;
        padding: 0.75rem 1rem;
    }

    .options-panel {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
        background: var(--card-bg);
        padding: 1rem;
        border-radius: var(--radius-md);
    }

    .panel-header {
        flex-direction: column;
        gap: 0.75rem;
        align-items: flex-start;
    }

    .panel-actions {
        width: 100%;
        justify-content: flex-end;
    }

    textarea {
        min-height: 250px;
    }

    .convert-btn {
        padding: 0.875rem 1.5rem;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 1rem 0.75rem;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .logo {
        width: 36px;
        height: 36px;
    }

    .mode-btn {
        font-size: 0.9rem;
        padding: 0.625rem 0.75rem;
    }

    .action-btn span {
        display: none;
    }

    .action-btn {
        padding: 0.5rem;
    }

    textarea {
        min-height: 200px;
        font-size: 0.85rem;
    }

    .convert-btn {
        width: 100%;
        justify-content: center;
    }

    .convert-section {
        flex-direction: column;
        width: 100%;
    }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #0f172a;
        --card-bg: #1e293b;
        --text-primary: #f1f5f9;
        --text-secondary: #94a3b8;
        --border-color: #334155;
        --input-bg: #0f172a;
    }

    select {
        background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    }
}