:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --dark: #0f172a;
    --light: #f8fafc;
    --gray: #64748b;
    --border: #cbd5e1;
    --card-bg: #ffffff;
    --accent: #0284c7;
    --accent-hover: #0369a1;
}

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

body {
    background-color: var(--light);
    color: var(--dark);
    line-height: 1.6;
}

header {
    text-align: center;
    padding: 4rem 1rem;
    background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 100%);
    color: white;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

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

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 3rem 1rem;
}

.section-title {
    text-align: center;
    margin-bottom: 2.5rem;
    font-size: 1.8rem;
    position: relative;
    padding-bottom: 0.5rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 3px;
    background-color: var(--primary);
    border-radius: 2px;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    transition: transform 0.2s, box-shadow 0.2s;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.card-highlight {
    border: 2px solid var(--accent);
    position: relative;
}

.badge {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--accent);
    color: white;
    padding: 0.25rem 1rem;
    border-radius: 20px;
    font-size: 0.75rem;
    text-transform: uppercase;
    font-weight: bold;
}

.icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.card h3 {
    margin-bottom: 0.5rem;
    font-size: 1.4rem;
}

.card p {
    color: var(--gray);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
}

.mobile-action-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.25rem;
    margin-top: auto;
}

.qr-box {
    background: #ffffff;
    border: 1px solid var(--border);
    padding: 0.75rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.02);
    display: flex;
    align-items: center;
    justify-content: center;
}

.qr-image {
    width: 120px;
    height: 120px;
    display: block;
}

.btn {
    display: block;
    width: 100%;
    background-color: var(--primary);
    color: white;
    text-decoration: none;
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    font-weight: 600;
    text-align: center;
}

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

.timeline {
    max-width: 800px;
    margin: 0 auto;
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
}

.version-block {
    position: relative;
    padding-left: 2rem;
    border-left: 2px solid var(--border);
    padding-bottom: 2rem;
}

.version-block:last-child {
    border-left: 2px solid transparent;
    padding-bottom: 0;
}

.version-block::before {
    content: '';
    position: absolute;
    left: -6px;
    top: 6px;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--primary);
}

.version-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
}

.version-number { font-weight: 700; }
.version-date { color: var(--gray); font-size: 0.85rem; }
.version-changes { list-style: none; }

.version-changes li {
    position: relative;
    padding-left: 1.25rem;
    margin-bottom: 0.25rem;
    font-size: 0.95rem;
}

.version-changes li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary);
}

.change-tag {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 700;
    padding: 0.1rem 0.4rem;
    border-radius: 4px;
    text-transform: uppercase;
    margin-right: 0.5rem;
}
.tag-added { background: #dcfce7; color: #166534; }
.tag-fixed { background: #fee2e2; color: #991b1b; }
.tag-improved { background: #e0f2fe; color: #075985; }

footer {
    text-align: center;
    padding: 2rem;
    color: var(--gray);
    font-size: 0.9rem;
    border-top: 1px solid #e2e8f0;
    margin-top: 4rem;
}