:root {
    --primary: #2563eb;
    --dark: #0f172a;
    --light: #f8fafc;
    --gray: #64748b;
    --card-bg: #ffffff;
    --radius: 12px;
}

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

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

/* App Header */
.app-header {
    position: sticky;
    top: 0;
    background: white;
    padding: 16px;
    font-weight: 600;
    font-size: 18px;
    box-shadow: 0 1px 4px rgba(0,0,0,0.05);
    z-index: 1000;
}

/* Container */
.container {
    padding: 16px;
    max-width: 600px;
    margin: auto;
}

/* Card */
.card {
    background: var(--card-bg);
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: 0 4px 10px rgba(0,0,0,0.05);
    margin-bottom: 20px;
}

/* Stats Grid */
.stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

.stat-box {
    background: white;
    padding: 18px;
    border-radius: var(--radius);
    text-align: center;
    box-shadow: 0 3px 8px rgba(0,0,0,0.04);
}

.stat-box h3 {
    font-size: 14px;
    color: var(--gray);
}

.stat-box h1 {
    margin-top: 8px;
    font-size: 22px;
}

/* Forms */
input, textarea {
    width: 100%;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid #e2e8f0;
    margin-bottom: 15px;
    font-size: 14px;
}

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

/* Buttons */
button {
    width: 100%;
    padding: 12px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
}

button:hover {
    opacity: 0.9;
}

/* Bottom Nav (Mobile App Style) */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: white;
    display: flex;
    justify-content: space-around;
    padding: 10px 0;
    box-shadow: 0 -2px 8px rgba(0,0,0,0.05);
}

.bottom-nav a {
    text-decoration: none;
    color: var(--gray);
    font-size: 13px;
    text-align: center;
}

.bottom-nav a.active {
    color: var(--primary);
}

/* Desktop */
@media (min-width: 768px) {
    .container {
        margin-top: 40px;
    }
}