:root { 
    --primary: #3b82f6; 
    --primary-hover: #2563eb;
    --surface: #ffffff; 
    --bg: #f8fafc; 
    --text-main: #0f172a; 
    --text-muted: #64748b;
}
body { 
    font-family: 'Inter', sans-serif; 
    background-color: var(--bg); 
    margin: 0; 
    display: flex; 
    justify-content: center; 
    align-items: center; 
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}
.app-container { 
    width: 100%; 
    max-width: 420px; 
    background: var(--surface); 
    padding: 2.5rem 2rem; 
    border-radius: 24px; 
    box-shadow: 0 10px 40px rgba(0,0,0,0.04); 
    box-sizing: border-box;
    border: 1px solid rgba(0,0,0,0.02);
    margin: 1rem;
}
.header-section {
    text-align: center;
    margin-bottom: 2rem;
}
.header-section h1 { 
    margin: 0; 
    color: var(--text-main); 
    font-size: 1.75rem; 
    font-weight: 700;
}
.header-section p {
    color: var(--text-muted);
    margin: 0.5rem 0 0 0;
    font-size: 0.95rem;
}
.form-group { margin-bottom: 1.25rem; }
label { display: block; margin-bottom: 0.5rem; color: var(--text-main); font-size: 0.9rem; font-weight: 500; }
input { 
    font-family: 'Inter', sans-serif;
    width: 100%; 
    padding: 0.85rem 1rem; 
    border: 1.5px solid #e2e8f0; 
    background-color: #f8fafc;
    border-radius: 12px; 
    font-size: 1rem; 
    box-sizing: border-box; 
    transition: all 0.2s ease-in-out; 
    color: var(--text-main);
}
input:focus { 
    outline: none; 
    background-color: #fff;
    border-color: var(--primary); 
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1); 
}
.btn-submit { 
    font-family: 'Inter', sans-serif;
    width: 100%; 
    background: var(--primary); 
    color: white; 
    border: none; 
    padding: 1rem; 
    border-radius: 12px; 
    font-size: 1rem; 
    font-weight: 600; 
    cursor: pointer; 
    margin-top: 1rem; 
    transition: background 0.2s, transform 0.1s; 
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.25);
}
.btn-submit:hover { background: var(--primary-hover); }
.btn-submit:active { transform: scale(0.98); }

.switch-link { 
    text-align: center; 
    display: block; 
    margin-top: 1.5rem; 
    color: var(--text-muted); 
    text-decoration: none; 
    font-size: 0.95rem; 
}
.switch-link b { color: var(--primary); }

.form-feedback {
    display: none;
    padding: 10px 15px;
    border-radius: 8px;
    background-color: #fee2e2;
    color: #b91c1c;
    font-size: 0.85rem;
    margin-bottom: 1rem;
    text-align: center;
    font-weight: 500;
}

/* Two columns logic CSS */
.double-col { display: flex; gap: 10px; }
.half-w { flex: 1; }

.dob-input {
    padding: 0.85rem 0.5rem;
    text-align: center;
}