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

:root {
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --secondary-color: #6c757d;
    --secondary-hover: #545b62;
    --border-color: #dee2e6;
    --text-color: #333;
    --text-light: #666;
    --bg-color: #fff;
    --bg-light: #f8f9fa;
    --shadow: 0 2px 4px rgba(0,0,0,0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.header {
    background-color: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    padding: 20px 0;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 24px;
    font-weight: 600;
    color: var(--primary-color);
}

.language-selector {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-color);
    font-size: 14px;
    cursor: pointer;
}

.nav {
    background-color: var(--bg-light);
    border-bottom: 1px solid var(--border-color);
}

.nav-list {
    list-style: none;
    display: flex;
    gap: 0;
}

.nav-item {
    position: relative;
}

.nav-item a {
    display: block;
    padding: 15px 25px;
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    border-bottom: 3px solid transparent;
}

.nav-item a:hover {
    color: var(--primary-color);
    background-color: var(--bg-color);
}

.nav-item.active a {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
    background-color: var(--bg-color);
}

.main {
    padding: 30px 0;
    min-height: calc(100vh - 200px);
}

.tool-section {
    display: none;
}

.tool-section.active {
    display: block;
}

.tool-title {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 25px;
    color: var(--text-color);
}

.tool-container {
    display: grid;
    gap: 25px;
}

.input-area, .output-area {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
}

.area-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.area-header label {
    font-weight: 600;
    font-size: 16px;
}

.button-group {
    display: flex;
    gap: 10px;
}

.textarea {
    width: 100%;
    min-height: 300px;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-family: "Courier New", Courier, monospace;
    font-size: 14px;
    line-height: 1.5;
    resize: vertical;
}

.textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.output {
    background-color: var(--bg-light);
    min-height: 300px;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-family: "Courier New", Courier, monospace;
    font-size: 14px;
    line-height: 1.5;
    overflow-x: auto;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    display: inline-block;
}

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

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

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

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

.btn-sm {
    padding: 6px 12px;
    font-size: 12px;
}

.current-time {
    background-color: var(--bg-light);
    padding: 15px;
    border-radius: 4px;
    margin-bottom: 25px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.current-time span:first-child {
    font-weight: 600;
}

#current-timestamp {
    font-family: "Courier New", Courier, monospace;
    font-size: 18px;
    color: var(--primary-color);
    font-weight: 600;
}

.converter-section {
    background-color: var(--bg-light);
    padding: 20px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.converter-section h3 {
    font-size: 18px;
    margin-bottom: 15px;
    color: var(--text-color);
}

.input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}

.input {
    flex: 1;
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 14px;
}

.input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.output-box {
    background-color: var(--bg-color);
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-family: "Courier New", Courier, monospace;
    font-size: 14px;
    line-height: 1.8;
}

.output-box .label {
    font-weight: 600;
    color: var(--text-light);
}

.output-box .value {
    color: var(--primary-color);
    font-weight: 600;
}

.footer {
    background-color: var(--bg-light);
    border-top: 1px solid var(--border-color);
    padding: 20px 0;
    text-align: center;
    color: var(--text-light);
    font-size: 14px;
}

.error {
    color: #dc3545;
    background-color: #f8d7da;
    border: 1px solid #f5c6cb;
    padding: 10px 15px;
    border-radius: 4px;
    margin-top: 10px;
}

.success {
    color: #155724;
    background-color: #d4edda;
    border: 1px solid #c3e6cb;
    padding: 10px 15px;
    border-radius: 4px;
    margin-top: 10px;
}

.json-key {
    color: #d63384;
}

.json-string {
    color: #198754;
}

.json-number {
    color: #0d6efd;
}

.json-boolean {
    color: #fd7e14;
}

.json-null {
    color: #6c757d;
}

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 15px;
    }
    
    .nav-list {
        flex-direction: column;
    }
    
    .nav-item a {
        padding: 12px 20px;
        border-bottom: 1px solid var(--border-color);
        border-left: 3px solid transparent;
    }
    
    .nav-item.active a {
        border-bottom-color: var(--border-color);
        border-left-color: var(--primary-color);
    }
    
    .area-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .button-group {
        width: 100%;
        flex-wrap: wrap;
    }
    
    .button-group .btn {
        flex: 1;
        min-width: 80px;
    }
    
    .input-group {
        flex-direction: column;
    }
    
    .current-time {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .textarea {
        min-height: 200px;
    }
    
    .output {
        min-height: 200px;
    }
}

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