:root {
    --primary-color: #6366f1;
    /* Indigo 500 */
    --primary-hover: #4f46e5;
    /* Indigo 600 */
    --secondary-bg: #f3f4f6;
    /* Gray 100 */
    --text-main: #1f2937;
    /* Gray 800 */
    --text-muted: #6b7280;
    /* Gray 500 */
    --border-color: #e5e7eb;
    /* Gray 200 */
    --radius: 1rem;
    --shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

ul {
    list-style: none;
}

a {
    text-decoration: none;
}

body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    color: var(--text-main);
}

/* Layout Wrapper */
.app-wrapper {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    width: 100%;
}

/* Header */
.main-header {
    padding: 1.5rem 0;
    background: transparent;
}

.logo {
    font-weight: 800;
    font-size: 1.75rem;
    color: #ffffff;
    letter-spacing: -0.05em;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.main-nav ul {
    display: flex;
    gap: 2rem;
}

.main-nav a {
    color: #ffffff;
    /* Pure white */
    font-weight: 600;
    opacity: 0.9;
    transition: all 0.2s;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

.main-nav a:hover {
    opacity: 1;
    transform: translateY(-1px);
}

/* Main Content - Centered Card */
.main-content {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem 0;
}

.converter-card {
    background: white;
    width: 100%;
    max-width: 1100px;
    border-radius: var(--radius);
    padding: 3rem;
    box-shadow: var(--shadow);
}

.card-header h1 {
    text-align: center;
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 2rem;
    color: var(--text-main);
}

/* Split Container */
.split-container {
    display: flex;
    flex-direction: row;
    align-items: stretch;
    gap: 2rem;
}

.split-pane {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.pane-label {
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
    display: block;
    color: var(--text-main);
}

textarea {
    width: 100%;
    height: 350px;
    padding: 1rem;
    border: 2px solid var(--secondary-bg);
    background-color: #fafafa;
    border-radius: 0.5rem;
    resize: none;
    font-size: 1rem;
    line-height: 1.5;
    outline: none;
    transition: all 0.2s;
}

textarea:focus {
    border-color: var(--primary-color);
    background-color: white;
}

textarea[readonly] {
    background-color: #f9fafb;
    cursor: default;
}

.pane-footer {
    margin-top: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.footer-center {
    justify-content: center;
}

/* Actions */
.actions-middle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 1rem;
}

.btn {
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s;
    border: none;
    border-radius: 0.5rem;
}

.btn-action {
    background-color: var(--secondary-bg);
    color: var(--text-main);
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.9rem;
}

.btn-action:hover {
    background-color: var(--primary-color);
    color: white;
    transform: scale(1.05);
}

.btn-copy {
    background-color: var(--primary-color);
    color: white;
    padding: 0.75rem 2rem;
    font-size: 1rem;
    box-shadow: 0 4px 6px rgba(79, 70, 229, 0.2);
}

.btn-copy:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 6px 8px rgba(79, 70, 229, 0.3);
}

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

/* Footer */
.main-footer {
    padding: 2rem 0;
    color: #ffffff;
    text-align: center;
    opacity: 0.9;
}

.main-footer a {
    color: #ffffff;
    margin: 0 1rem;
    font-weight: 600;
    text-decoration: underline;
    text-decoration-color: rgba(255, 255, 255, 0.4);
    text-underline-offset: 4px;
}

.main-footer a:hover {
    text-decoration-color: #ffffff;
    opacity: 1;
}

/* Responsive */
@media (max-width: 768px) {
    .split-container {
        flex-direction: column;
    }

    .actions-middle {
        flex-direction: row;
        justify-content: center;
        padding: 1rem 0;
    }

    .btn-action {
        width: auto;
        padding: 0 1.5rem;
        height: 40px;
    }

    .converter-card {
        padding: 1.5rem;
    }

    textarea {
        height: 200px;
    }
}