* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --bg-color: #F5F5F5;
    --card-color: #FFFFFF;
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-light: #999999;
    --border-color: #000000;
    --divider-color: #E5E5E5;
    --active-color: #07C160;
    --expired-color: #FA5151;
    --paused-color: #FF9F0A;
    --draft-color: #8E8E93;
    
    font-size: clamp(0.875rem, 2vw, 1rem); /* 14-16px */
}

body {
    background-color: #F5F5F5;
    color: #333333;
    line-height: 1.5;
    min-height: 100vh;
}

.header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: clamp(0.75rem, 2vw, 0.9375rem);
    display: flex;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 10;
}

.back-btn {
    color: white;
    font-size: clamp(1.5rem, 3vw, 1.75rem);
    background: none;
    border: 0.2rem solid #ffffff;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: clamp(0.25rem, 0.75vw, 0.3125rem);
    padding: clamp( 0.3rem, 0.75vw, 0.3125rem);
    border-radius: 10%;
    transition: background-color 0.2s;
}

.back-btn:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.header-title {
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 500;
    text-align: center;
    flex: 1;
    padding-right: clamp(2.5rem, 6vw, 3rem);
}

.container {
    padding: clamp(1rem, 3vw, 1.25rem);
    max-width: 37.5rem;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: calc(100vh - 3.75rem);
}

.qr-card {
    background: white;
    border-radius: 0.75rem;
    padding: clamp(1.5rem, 4vw, 2rem);
    box-shadow: 0 0.125rem 0.5rem rgba(0, 0, 0, 0.1);
    text-align: center;
    width: 100%;
    max-width: 18.75rem;
}

.qr-code {
    width: 100%;
    padding: 0.625rem;
    background: white;
    border: 0.0625rem solid #E0E0E0;
    border-radius: 0.5rem;
}

.qr-code img {
    width: 100%;
    height: auto;
    display: block;
}

@media (max-width: 30rem) {
    .container {
        padding: 0.75rem;
    }
    
    .qr-card {
        padding: 1.25rem;
    }
}