:root {
    --bg-app: #0f172a;
    /* Slate 900 */
    --bg-card: #1e293b;
    /* Slate 800 */
    --bg-card-hover: #334155;
    --accent: #3b82f6;
    /* Blue 500 */
    --accent-dark: #2563eb;
    --accent-glow: rgba(59, 130, 246, 0.4);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --success: #10b981;
    --border: #334155;
    --danger: #ef4444;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: #020617;
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Toast Notification */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1000;
}

.toast {
    background-color: var(--success);
    color: white;
    padding: 1rem 1.5rem;
    border-radius: 0.5rem;
    margin-bottom: 0.5rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    animation: slideIn 0.3s ease-out;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* App Wrapper */
.app-wrapper {
    width: 100%;
    /* Maximize width but keep some breathing room if very large screen */
    max-width: 1600px;
    margin: 0 auto;
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Navbar */
.navbar {
    height: 70px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
    background-color: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 100;
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--accent);
}

.nav-tabs {
    display: flex;
    gap: 0.5rem;
    background: rgba(30, 41, 59, 0.5);
    padding: 0.25rem;
    border-radius: 0.75rem;
}

.nav-tab {
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: 0.5rem;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-tab:hover {
    color: var(--text-primary);
}

.nav-tab.active {
    background-color: var(--accent);
    color: white;
    box-shadow: 0 0 15px var(--accent-glow);
}

/* Content */
.content-area {
    padding: 2rem;
    flex: 1;
}

/* Privacy Banner */
.privacy-banner {
    background: linear-gradient(90deg, rgba(16, 185, 129, 0.1), transparent);
    border-left: 4px solid var(--success);
    padding: 1rem;
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 2rem;
    font-size: 0.875rem;
}

/* Cards & Grid */
.section-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.feature-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    padding: 1.5rem;
    transition: all 0.2s;
}

.feature-card:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}

.feature-card.active {
    border-color: var(--accent);
    box-shadow: 0 0 0 2px var(--accent);
}

/* Buttons */
.btn {
    padding: 0.6rem 1.2rem;
    border-radius: 0.5rem;
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
}

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

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

.btn-secondary {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background-color: var(--bg-card-hover);
}

/* Unique Batch UI */
.batch-upload-container {
    border: 2px dashed var(--border);
    background: rgba(30, 41, 59, 0.3);
    border-radius: 1rem;
    padding: 4rem 2rem;
    text-align: center;
    transition: all 0.2s;
}

.batch-upload-container:hover {
    border-color: var(--accent);
    background: rgba(59, 130, 246, 0.05);
}

/* Training Curves */
.charts-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.chart-box {
    background: var(--bg-card);
    padding: 1rem;
    border-radius: 0.75rem;
    height: 300px;
}

/* Footer */
.app-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border);
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
    background-color: var(--bg-app);
    margin-top: auto;
}

input[type="range"] {
    width: 100%;
    margin: 0.5rem 0;
    accent-color: var(--accent);
}

.hidden {
    display: none !important;
}