:root {
    /* Colors */
    --bg-dark: #0a0a0a;
    --bg-card: #141414;
    --bg-input: #1f1f1f;

    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --text-accent: #00f2ff;

    --primary-color: #00f2ff;
    /* Cyan Neon */
    --primary-glow: rgba(0, 242, 255, 0.4);

    --secondary-color: #ff00aa;
    /* Magenta Neon */
    --secondary-glow: rgba(255, 0, 170, 0.4);

    --success-color: #00ff9d;
    --warning-color: #ffcc00;
    --danger-color: #ff4d4d;

    /* Spacing & Layout */
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;

    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;

    /* Animation */
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset & Base */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-primary);
    font-family: 'Outfit', sans-serif;
    line-height: 1.5;
    overflow-x: hidden;
    min-height: 100vh;
    overflow-x: hidden;
    min-height: 100vh;
}

/* Typography */
h1,
h2,
h3 {
    font-family: 'Space Grotesk', sans-serif;
    font-weight: 600;
    line-height: 1.2;
}

h1 {
    font-size: 1.5rem;
    letter-spacing: -0.02em;
}

h2 {
    font-size: 2rem;
    margin-bottom: var(--space-xs);
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-bottom: var(--space-lg);
}

/* Layout Shell */
.app-container {
    width: 100%;
    max-width: 800px;
    margin-inline: auto;
    /* Force centering */
    padding: var(--space-md);
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

/* Header */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-md) 0;
    margin-bottom: var(--space-md);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    color: var(--primary-color);
    text-shadow: 0 0 10px var(--primary-glow);
}

/* Navigation */
.main-nav {
    display: flex;
    background: var(--bg-card);
    padding: 4px;
    border-radius: var(--radius-lg);
    gap: 4px;
}

.nav-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 8px 16px;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-family: inherit;
    font-weight: 500;
    transition: var(--transition-fast);
}

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

.nav-btn.active {
    background: var(--bg-input);
    color: var(--primary-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

/* Panels */
.panel {
    display: block;
    animation: fadeIn var(--transition-smooth);
    margin-bottom: var(--space-xl);
    padding-bottom: var(--space-xl);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.panel:last-child {
    border-bottom: none;
}

.panel.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

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

/* Footer */
.main-footer {
    text-align: center;
    margin-top: auto;
    padding: var(--space-xl) 0;
    color: var(--text-secondary);
    font-size: 0.8rem;
    opacity: 0.6;
    width: 100%;
}

/* Utilities */
.hidden {
    display: none !important;
}

/* Placeholder */
/* Section Styles */

/* Calculator Layout */
.calculator-grid {
    display: grid;
    grid-gap: var(--space-lg);
    align-items: start;
}

@media (min-width: 768px) {
    .calculator-grid {
        grid-template-columns: 1fr 1fr;
    }
}

.input-card,
.result-card {
    background: var(--bg-card);
    padding: var(--space-lg);
    border-radius: var(--radius-md);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.result-card {
    margin-top: var(--space-lg);
}

/* Controls */
.control-group {
    margin-bottom: var(--space-lg);
}

.label-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--space-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.value-display {
    color: var(--primary-color);
    font-weight: 600;
    font-family: 'Space Grotesk', monospace;
}

.value-input {
    background: transparent;
    border: none;
    color: var(--primary-color);
    font-weight: 600;
    font-family: 'Space Grotesk', monospace;
    font-size: 1rem;
    text-align: right;
    width: 100px;
    cursor: text;
    border-bottom: 2px solid rgba(255, 255, 255, 0.1);
    transition: var(--transition-fast);
    background: rgba(255, 255, 255, 0.05);
    border-radius: 4px;
    padding: 2px 8px;

}

.value-input:focus {
    outline: none;
    border-bottom-color: var(--primary-color);
}

/* Toggle Switch */
.toggle-container {
    background: var(--bg-input);
    border-radius: var(--radius-sm);
    padding: 2px;
    display: inline-flex;
}

.unit-toggle {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 4px 12px;
    font-size: 0.8rem;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition-fast);
}

.unit-toggle.active {
    background: var(--text-secondary);
    color: var(--bg-dark);
}

.sex-toggle {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 6px 16px;
    font-size: 0.9rem;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition-fast);
}

.sex-toggle.active {
    background: var(--text-secondary);
    color: var(--bg-dark);
    box-shadow: 0 0 10px rgba(255, 255, 255, 0.2);
}

/* Styled Slider */
input[type=range] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    background: transparent;
}

input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    height: 20px;
    width: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    box-shadow: 0 0 10px var(--primary-glow);
    cursor: pointer;
    margin-top: -8px;
    transition: transform 0.1s;
}

input[type=range]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    background: var(--bg-input);
    border-radius: 2px;
}

/* Result Card */
.slider-container {
    position: relative;
    padding-bottom: 10px;
}

.slider-pips {
    display: flex;
    justify-content: space-between;
    padding: 0 10px;
    margin-top: -14px;
    pointer-events: none;
    width: 100%;
    box-sizing: border-box;
}

.pip {
    width: 4px;
    height: 4px;
    background: var(--text-secondary);
    border-radius: 50%;
    opacity: 0.5;
}

.warning-message {
    font-size: 0.8rem;
    color: var(--danger-color);
    margin-top: 8px;
    display: flex;
    align-items: center;
    gap: 6px;
    animation: fadeIn var(--transition-fast);
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--space-md);
}

.category-badge {
    font-size: 0.8rem;
    padding: 4px 12px;
    border-radius: 100px;
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
}

.main-number {
    font-size: 4rem;
    font-weight: 700;
    line-height: 1;
    margin-bottom: var(--space-md);
    background: linear-gradient(135deg, #fff, #aaa);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    font-family: 'Space Grotesk', sans-serif;
}

/* Gauge */
.gauge-container {
    position: relative;
    height: 30px;
    margin-bottom: var(--space-md);
}

.gauge-bar {
    display: flex;
    height: 8px;
    width: 100%;
    border-radius: 4px;
    overflow: hidden;
    position: absolute;
    top: 11px;
}

.gauge-segment {
    opacity: 0.3;
}

.gauge-segment.under {
    background: var(--warning-color);
}

.gauge-segment.normal {
    background: var(--success-color);
}

.gauge-segment.over {
    background: var(--warning-color);
}

.gauge-segment.obese {
    background: var(--danger-color);
}

.gauge-marker {
    width: 4px;
    height: 20px;
    background: #fff;
    position: absolute;
    top: 5px;
    left: 0%;
    /* Dynamic */
    border-radius: 2px;
    box-shadow: 0 0 8px rgba(255, 255, 255, 0.5);
    transition: left var(--transition-smooth);
}

.result-feedback {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

/* BMR Module Styles */
.multi-col {
    display: flex;
    gap: var(--space-md);
}

.col-half {
    flex: 1;
}

.styled-input {
    width: 100%;
    background: var(--bg-input);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    padding: 8px 12px;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-family: inherit;
}

.styled-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--primary-glow);
}

.activity-desc {
    font-size: 0.9rem;
    color: var(--primary-color);
    margin-top: var(--space-xs);
    text-align: right;
}

.separator {
    border: 0;
    height: 1px;
    background: rgba(255, 255, 255, 0.1);
    margin: var(--space-md) 0;
}

.main-number.small {
    font-size: 2.5rem;
    margin-bottom: 0;
}

.subtitle.sm {
    margin-bottom: var(--space-xs);
    font-size: 0.8rem;
}

/* Goals Module */
.chart-wrapper {
    position: relative;
    height: 250px;
    width: 100%;
    margin-bottom: var(--space-md);
}

.input-with-suffix {
    position: relative;
    display: flex;
    align-items: center;
}

.suffix {
    position: absolute;
    right: 12px;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.info-box {
    background: rgba(255, 255, 255, 0.03);
    padding: var(--space-md);
    border-radius: var(--radius-sm);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.highlight-text {
    font-weight: 700;
    color: var(--primary-color);
}

.prediction-text {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-primary);
}

.small-note {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 4px;
}

/* Accessibility & Polish */
@media (prefers-reduced-motion: reduce) {
    :root {
        --transition-fast: 0s;
        --transition-smooth: 0s;
    }

    .panel {
        animation: none;
    }

    .gauge-marker {
        transition: none;
    }
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-dark);
}

::-webkit-scrollbar-thumb {
    background: #333;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #555;
}



/* Feature Updates */
.mode-toggle-group {
    width: 100%;
    display: flex;
}

.mode-toggle {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 8px;
    font-size: 0.9rem;
    cursor: pointer;
    border-radius: 6px;
    transition: var(--transition-fast);
}

.mode-toggle.active {
    background: var(--bg-card);
    color: var(--primary-color);
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
}

.mode-helper-text {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 4px;
    text-align: center;
    font-style: italic;
}

.text-btn {
    background: none;
    border: none;
    color: var(--primary-color);
    font-size: 0.8rem;
    text-decoration: underline;
    cursor: pointer;
    margin-top: 4px;
    padding: 0;
}

.plan-badge {
    display: inline-block;
    font-size: 0.75rem;
    border: 1px solid var(--text-secondary);
    color: var(--text-secondary);
    padding: 2px 8px;
    border-radius: 4px;
    margin-top: 8px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.plan-badge.match {
    border-color: var(--success-color);
    color: var(--success-color);
}

.plan-badge.mismatch {
    border-color: var(--warning-color);
    color: var(--warning-color);
}

.goal-maintenance-panel {
    animation: fadeIn var(--transition-smooth);
}

.goal-maintenance-panel h4 {
    font-size: 1rem;
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
}

/* Accessibility Focus States */
.nav-btn:focus-visible,
.unit-toggle:focus-visible,
.mode-toggle:focus-visible,
.sex-toggle:focus-visible,
input[type=range]:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
    box-shadow: 0 0 10px var(--primary-glow);
}