:root {
    /* HSL Variables for easy theming */
    --h-primary: 210;
    --s-primary: 100%;
    --l-primary: 50%;
    
    --bg-color: hsl(0, 0%, 96%);
    --surface-color: hsl(0, 0%, 100%);
    --text-main: hsl(0, 0%, 20%);
    --text-muted: hsl(0, 0%, 40%);
    --border-color: hsl(0, 0%, 90%);
    
    --danger: hsl(0, 80%, 60%);
    --success: hsl(120, 60%, 45%);
    
    --radius: 12px;
    --spacing: 16px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: hsl(0, 0%, 12%);
        --surface-color: hsl(0, 0%, 18%);
        --text-main: hsl(0, 0%, 95%);
        --text-muted: hsl(0, 0%, 70%);
        --border-color: hsl(0, 0%, 25%);
    }
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    padding-bottom: 80px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing);
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    view-transition-name: site-header;
}

main {
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing);
    display: grid;
    gap: var(--spacing);
}

.card {
    background: var(--surface-color);
    padding: var(--spacing);
    border-radius: var(--radius);
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
}

.hidden {
    display: none !important;
}

/* Forms & Inputs */
.input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: var(--spacing);
}

input[type="password"] {
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-color);
    color: var(--text-main);
    font-size: 16px;
}

/* Buttons */
.btn {
    padding: 12px var(--spacing);
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    width: 100%;
    transition: opacity 0.2s;
}

.btn:active {
    opacity: 0.8;
}

.primary { background: hsl(var(--h-primary), var(--s-primary), var(--l-primary)); color: white; }
.danger-btn { background: var(--danger); color: white; }
.action-btn { background: var(--success); color: white; margin-top: var(--spacing); }

/* Upload Area */
.upload-label {
    display: block;
    padding: 32px;
    border: 2px dashed var(--border-color);
    border-radius: var(--radius);
    text-align: center;
    cursor: pointer;
    font-weight: 600;
}

.upload-label input {
    display: none;
}

#imagePreview {
    width: 100%;
    max-height: 300px;
    object-fit: contain; /* Handles screenshots elegantly */
    border-radius: 8px;
    margin-top: var(--spacing);
}

/* Dashboard & Timeline */
.stats-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing);
    text-align: center;
    margin-top: 12px;
}

.stat-box {
    background: var(--bg-color);
    padding: var(--spacing);
    border-radius: 8px;
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    color: hsl(var(--h-primary), var(--s-primary), var(--l-primary));
}

.meal-card {
    border-left: 4px solid hsl(var(--h-primary), var(--s-primary), var(--l-primary));
    margin-bottom: var(--spacing);
}

.meal-item {
    display: flex;
    justify-content: space-between;
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color);
}

.meal-item:last-child { border: none; }

.meal-note {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
}

/* Loading Spinner */
.spinner {
    border: 4px solid var(--border-color);
    border-top: 4px solid hsl(var(--h-primary), var(--s-primary), var(--l-primary));
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 0 auto var(--spacing);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

footer {
    position: fixed;
    bottom: 0;
    width: 100%;
    padding: var(--spacing);
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: center;
}

footer .btn {
    max-width: 600px;
}