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

:root {
    --primary-color: #3498db;
    --primary-dark: #2980b9;
    --secondary-color: #2ecc71;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
    --bg-color: #f5f7fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-muted: #7f8c8d;
    --border-color: #e1e8ed;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.15);
}

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;
}

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

header {
    text-align: center;
    padding: 40px 20px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    border-radius: 12px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

header p {
    font-size: 1.1rem;
    opacity: 0.9;
}

.nav-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
    margin-bottom: 30px;
    padding: 0 10px;
}

.tab-btn {
    padding: 12px 24px;
    border: none;
    background: var(--card-bg);
    color: var(--text-color);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.tab-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    color: var(--primary-color);
}

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

.tab-content {
    display: none;
    animation: fadeIn 0.3s ease;
}

.tab-content.active {
    display: block;
}

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

section {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

section h2 {
    margin-bottom: 20px;
    color: var(--text-color);
    font-size: 1.5rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 10px;
}

.tool-box {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.input-group label {
    font-weight: 500;
    color: var(--text-muted);
    font-size: 0.9rem;
}

textarea, input[type="text"], input[type="datetime-local"], select {
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 0.95rem;
    transition: border-color 0.3s ease;
    font-family: inherit;
}

textarea:focus, input:focus, select:focus {
    outline: none;
    border-color: var(--primary-color);
}

textarea {
    min-height: 150px;
    resize: vertical;
}

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

button {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    background: var(--primary-color);
    color: white;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

button:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
}

button:active {
    transform: translateY(0);
}

.btn-group button:nth-child(2) {
    background: var(--secondary-color);
}

.btn-group button:nth-child(2):hover {
    background: #27ae60;
}

.btn-group button:last-child {
    background: var(--text-muted);
}

.btn-group button:last-child:hover {
    background: #6c7a7d;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
}

.checkbox-label input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.stats {
    background: var(--bg-color);
    padding: 15px;
    border-radius: 8px;
    font-size: 0.9rem;
}

.stats p {
    margin: 5px 0;
}

.result-box {
    background: var(--bg-color);
    padding: 15px;
    border-radius: 8px;
    min-height: 100px;
    white-space: pre-wrap;
    word-break: break-all;
}

.timestamp-display {
    display: flex;
    align-items: center;
    gap: 15px;
    background: var(--bg-color);
    padding: 15px;
    border-radius: 8px;
}

.timestamp-display span {
    font-family: 'Courier New', monospace;
    font-size: 1.2rem;
    color: var(--primary-color);
    font-weight: bold;
}

.converter {
    background: var(--bg-color);
    padding: 20px;
    border-radius: 8px;
    margin-top: 15px;
}

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

.input-row {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.input-row input, .input-row select {
    flex: 1;
    min-width: 150px;
}

.result {
    margin-top: 15px;
    padding: 15px;
    background: white;
    border-radius: 6px;
    font-family: 'Courier New', monospace;
}

.color-picker-section {
    display: flex;
    align-items: center;
    gap: 30px;
    flex-wrap: wrap;
}

input[type="color"] {
    width: 100px;
    height: 50px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

.color-preview {
    width: 150px;
    height: 100px;
    border-radius: 8px;
    border: 2px solid var(--border-color);
    transition: background-color 0.3s ease;
}

.color-conversions {
    margin-top: 20px;
}

.copy-row {
    display: flex;
    gap: 10px;
}

.copy-row input {
    flex: 1;
}

.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: #333;
    color: white;
    padding: 12px 24px;
    border-radius: 8px;
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 1000;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

footer {
    text-align: center;
    padding: 30px;
    color: var(--text-muted);
    margin-top: 30px;
}

.match-highlight {
    background: #ffeb3b;
    padding: 2px 4px;
    border-radius: 3px;
}

.error {
    color: var(--danger-color);
}

.success {
    color: var(--secondary-color);
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }

    header h1 {
        font-size: 1.8rem;
    }

    .nav-tabs {
        gap: 8px;
    }

    .tab-btn {
        padding: 10px 16px;
        font-size: 0.85rem;
    }

    section {
        padding: 20px;
    }

    .btn-group {
        justify-content: center;
    }

    button {
        padding: 8px 16px;
        font-size: 0.85rem;
    }

    .input-row {
        flex-direction: column;
    }

    .input-row input, .input-row select {
        width: 100%;
    }

    .color-picker-section {
        flex-direction: column;
        align-items: flex-start;
    }
}

@media (max-width: 480px) {
    header {
        padding: 25px 15px;
    }

    header h1 {
        font-size: 1.5rem;
    }

    section h2 {
        font-size: 1.2rem;
    }

    .tab-btn {
        padding: 8px 12px;
        font-size: 0.8rem;
    }
}