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

body {
    font-family: 'Arial', sans-serif;
    line-height: 1.6;
    background-color: #f5f5f5;
    color: #333;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background-color: #fff;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

h1 {
    text-align: center;
    margin-bottom: 30px;
    color: #2c3e50;
}

h2 {
    margin-bottom: 20px;
    color: #3498db;
}

h3 {
    color: #2c3e50;
    margin-bottom: 15px;
}

/* Instructions Section */
.instructions {
    margin-bottom: 30px;
    border: 1px solid #e0e0e0;
    border-radius: 5px;
    overflow: hidden;
}

.instructions-toggle {
    width: 100%;
    padding: 12px 15px;
    background-color: #f8f9fa;
    border: none;
    text-align: left;
    font-size: 16px;
    font-weight: bold;
    color: #3498db;
    cursor: pointer;
    transition: background-color 0.3s;
}

.instructions-toggle:hover {
    background-color: #e9ecef;
}

.instructions-content {
    display: none;
    padding: 15px;
    border-top: 1px solid #e0e0e0;
    background-color: #f8f9fa;
}

.instructions-content ol {
    margin-left: 20px;
}

.instructions-content li {
    margin-bottom: 8px;
}

/* Tabs */
.tabs {
    display: flex;
    margin-bottom: 20px;
    border-bottom: 2px solid #ddd;
}

.tab-btn {
    padding: 10px 20px;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 16px;
    font-weight: bold;
    color: #777;
    transition: all 0.3s ease;
}

.tab-btn:hover {
    color: #3498db;
}

.tab-btn.active {
    color: #3498db;
    border-bottom: 2px solid #3498db;
    margin-bottom: -2px;
}

.tab-pane {
    display: none;
    padding: 20px 0;
}

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

/* Form */
.converter-form {
    display: grid;
    grid-template-columns: 1fr;
    gap: 15px;
}

@media (min-width: 768px) {
    .converter-form {
        grid-template-columns: 1fr 1fr;
    }
}

.form-group {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

input[type="text"] {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 16px;
}

input[type="text"]:focus {
    border-color: #3498db;
    outline: none;
    box-shadow: 0 0 5px rgba(52, 152, 219, 0.5);
}

/* FAQ Section */
.faq {
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid #e0e0e0;
}

.faq-item {
    margin-bottom: 15px;
    border: 1px solid #e0e0e0;
    border-radius: 5px;
    overflow: hidden;
}

.faq-question {
    padding: 12px 15px;
    background-color: #f8f9fa;
    font-weight: bold;
    cursor: pointer;
    position: relative;
    transition: background-color 0.3s;
}

.faq-question:hover {
    background-color: #e9ecef;
}

.faq-question::after {
    content: '+';
    position: absolute;
    right: 15px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 18px;
    color: #3498db;
}

.faq-answer {
    display: none;
    padding: 15px;
    border-top: 1px solid #e0e0e0;
    background-color: #fff;
}

/* Tip Container */
.tip-container {
    margin: 15px 0;
}

.size-tip {
    padding: 12px 15px;
    background-color: #e8f4fd;
    border-left: 4px solid #3498db;
    border-radius: 4px;
    color: #2c3e50;
    font-size: 14px;
    line-height: 1.5;
    display: none;
}

.size-tip.visible {
    display: block;
    animation: fadeIn 0.5s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}