/* ========================================
   FRIEND RECOMMENDER - MODERN UI
   ======================================== */

/* Global Variables */
:root {
    /* Colors - Professional Blue/Slate Palette */
    --primary: #0f172a;
    --primary-light: #1e293b;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --accent-light: #60a5fa;
    --accent-glow: rgba(59, 130, 246, 0.4);

    /* Backgrounds */
    --bg-main: #f8fafc;
    --bg-card: #ffffff;
    --bg-subtle: #f1f5f9;
    --bg-hover: #e0e7ff;

    /* Text */
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;

    /* Borders */
    --border-color: #e2e8f0;
    --border-hover: #cbd5e1;
    --border-focus: #3b82f6;

    /* Shadows */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.3);

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========================================
   RESET & BASE STYLES
   ======================================== */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    background: linear-gradient(135deg, #f8fafc 0%, #e0e7ff 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    position: relative;
    overflow-x: hidden;
}

/* Subtle animated background pattern */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        radial-gradient(circle at 20% 50%, rgba(59, 130, 246, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(139, 92, 246, 0.05) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
    animation: backgroundPulse 15s ease-in-out infinite;
}

@keyframes backgroundPulse {

    0%,
    100% {
        opacity: 0.5;
    }

    50% {
        opacity: 1;
    }
}

/* ========================================
   TYPOGRAPHY
   ======================================== */

h1,
h2,
h3,
h4,
h5,
h6 {
    color: var(--primary);
    line-height: 1.3;
    font-weight: 700;
    letter-spacing: -0.02em;
}

h1 {
    font-size: 2.25rem;
    letter-spacing: -0.03em;
}

h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

h4 {
    font-size: 1.125rem;
}

p {
    margin-bottom: 1rem;
    line-height: 1.65;
}

.text-sm {
    font-size: 0.875rem;
    line-height: 1.5;
}

.text-muted {
    color: var(--text-secondary);
}

code {
    background: var(--bg-subtle);
    padding: 0.125rem 0.375rem;
    border-radius: var(--radius-sm);
    font-size: 0.875em;
    font-family: 'Courier New', monospace;
    color: var(--accent);
}

/* ========================================
   LAYOUT
   ======================================== */

.app-wrapper {
    display: flex;
    min-height: 100vh;
    position: relative;
    z-index: 1;
}

.app-sidebar {
    width: 280px;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-right: 1px solid var(--border-color);
    padding: 2rem 1.5rem;
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    display: flex;
    flex-direction: column;
    z-index: 100;
    box-shadow: var(--shadow-sm);
    animation: slideInLeft 0.4s ease-out;
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }

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

.app-content {
    flex: 1;
    margin-left: 280px;
    padding: 2.5rem 3rem;
    max-width: 1200px;
    animation: fadeInUp var(--transition-slow);
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

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

/* ========================================
   SIDEBAR
   ======================================== */

.sidebar-header {
    margin-bottom: 2.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.logo {
    font-size: 1.375rem;
    font-weight: 800;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.625rem;
    text-decoration: none;
    transition: all var(--transition-fast);
    letter-spacing: -0.03em;
}

.logo:hover {
    color: var(--accent);
    transform: translateX(2px);
}

.logo .icon-lg {
    width: 28px;
    height: 28px;
    color: var(--accent);
    animation: floatIcon 3s ease-in-out infinite;
}

@keyframes floatIcon {

    0%,
    100% {
        transform: translateY(0px);
    }

    50% {
        transform: translateY(-3px);
    }
}

.sidebar-nav {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    width: 100%;
    padding: 0.875rem 1rem;
    border: none;
    border-radius: var(--radius-md);
    background: transparent;
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 0.9375rem;
    cursor: pointer;
    transition: all var(--transition-base);
    text-align: left;
    position: relative;
    overflow: hidden;
}

.nav-btn::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 3px;
    background: linear-gradient(180deg, var(--accent) 0%, var(--accent-light) 100%);
    transform: scaleY(0);
    transition: transform var(--transition-base);
}

.nav-btn .icon {
    font-size: 1.25rem;
    transition: all var(--transition-fast);
}

.nav-btn:hover {
    background: var(--bg-subtle);
    color: var(--primary);
    transform: translateX(4px);
}

.nav-btn:hover .icon {
    transform: scale(1.15) rotate(5deg);
    color: var(--accent);
}

.nav-btn.active {
    background: linear-gradient(135deg, var(--bg-hover) 0%, rgba(224, 231, 255, 0.5) 100%);
    color: var(--accent);
    box-shadow: inset 0 1px 3px rgba(59, 130, 246, 0.1);
}

.nav-btn.active::before {
    transform: scaleY(1);
}

.nav-btn.active .icon {
    color: var(--accent);
}

/* ========================================
   CARDS & CONTAINERS
   ======================================== */

.card {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    padding: 2rem;
    border: 1px solid rgba(226, 232, 240, 0.8);
    margin-bottom: 2rem;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent) 0%, var(--accent-light) 50%, var(--accent) 100%);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
    border-color: rgba(59, 130, 246, 0.2);
}

.card:hover::before {
    opacity: 1;
}

/* ========================================
   FORMS
   ======================================== */

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--primary);
    letter-spacing: -0.01em;
    transition: color var(--transition-fast);
}

input[type="text"],
select,
textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.9375rem;
    font-family: inherit;
    transition: all var(--transition-base);
    background-color: var(--bg-card);
    color: var(--text-primary);
    outline: none;
}

input[type="text"]:hover,
select:hover,
textarea:hover {
    border-color: var(--border-hover);
    box-shadow: 0 0 0 1px var(--border-hover);
}

input[type="text"]:focus,
select:focus,
textarea:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
    transform: translateY(-1px);
}

input[type="text"]::placeholder,
textarea::placeholder {
    color: var(--text-muted);
}

textarea {
    resize: vertical;
    min-height: 120px;
    line-height: 1.6;
}

select {
    cursor: pointer;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.form-row .form-group {
    margin-bottom: 0;
}

/* ========================================
   BUTTONS
   ======================================== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-hover) 100%);
    color: white;
    font-weight: 600;
    font-size: 0.9375rem;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-base);
    width: 100%;
    box-shadow: var(--shadow-md), 0 4px 14px rgba(59, 130, 246, 0.25);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.6s;
}

.btn::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:hover {
    background: linear-gradient(135deg, var(--accent-hover) 0%, #1d4ed8 100%);
    box-shadow: var(--shadow-lg), 0 8px 20px rgba(59, 130, 246, 0.35);
    transform: translateY(-3px);
}

.btn:hover::before {
    left: 100%;
}

.btn:active::after {
    width: 300px;
    height: 300px;
    transition: 0s;
}

.btn:active {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md), 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: var(--shadow-sm);
}

.btn:disabled:hover {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-hover) 100%);
    transform: none;
    box-shadow: var(--shadow-sm);
}

.btn-secondary {
    background: var(--bg-card);
    border: 2px solid var(--border-color);
    color: var(--text-primary);
    box-shadow: var(--shadow-xs);
}

.btn-secondary:hover {
    background: var(--bg-subtle);
    border-color: var(--accent);
    box-shadow: var(--shadow-sm);
    color: var(--accent);
}

.btn-secondary::before {
    display: none;
}

/* ========================================
   RECOMMENDATIONS
   ======================================== */

.recommendation-list {
    display: grid;
    gap: 1.25rem;
}

.recommendation-card {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 1.75rem;
    transition: all var(--transition-slow);
    position: relative;
    overflow: hidden;
    cursor: pointer;
    animation: slideInCard 0.5s ease-out backwards;
}

/* Staggered animation for cards */
.recommendation-card:nth-child(1) {
    animation-delay: 0.05s;
}

.recommendation-card:nth-child(2) {
    animation-delay: 0.1s;
}

.recommendation-card:nth-child(3) {
    animation-delay: 0.15s;
}

.recommendation-card:nth-child(4) {
    animation-delay: 0.2s;
}

.recommendation-card:nth-child(5) {
    animation-delay: 0.25s;
}

@keyframes slideInCard {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }

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

.recommendation-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--accent) 0%, var(--accent-light) 100%);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-slow);
}

.recommendation-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl), 0 0 30px rgba(59, 130, 246, 0.15);
    border-color: var(--accent-light);
}

.recommendation-card:hover::before {
    transform: scaleX(1);
}

.rec-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
    padding-right: 3rem;
}

.rec-rank {
    position: absolute;
    top: 0;
    right: 0;
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-hover) 100%);
    color: white;
    font-size: 0.75rem;
    font-weight: 700;
    padding: 0.5rem 1rem;
    border-bottom-left-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    letter-spacing: 0.05em;
    animation: pulseRank 2s ease-in-out infinite;
}

@keyframes pulseRank {

    0%,
    100% {
        box-shadow: var(--shadow-md);
    }

    50% {
        box-shadow: var(--shadow-lg), 0 0 15px rgba(59, 130, 246, 0.4);
    }
}

.rec-name {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 0.25rem;
    letter-spacing: -0.02em;
}

.rec-location {
    font-size: 0.875rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.375rem;
    margin-top: 0.25rem;
}

.rec-interests {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    background: linear-gradient(135deg, var(--bg-subtle) 0%, rgba(241, 245, 249, 0.6) 100%);
    padding: 1rem 1.25rem;
    border-radius: var(--radius-md);
    margin: 1rem 0;
    border-left: 3px solid var(--accent-light);
    line-height: 1.6;
}

.rec-metrics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: 0.75rem;
    margin-top: 1rem;
}

.metric {
    background: var(--bg-subtle);
    padding: 0.75rem 0.5rem;
    border-radius: var(--radius-md);
    text-align: center;
    border: 1px solid var(--border-color);
    transition: all var(--transition-base);
}

.metric:hover {
    background: white;
    box-shadow: var(--shadow-sm);
    transform: translateY(-3px) scale(1.02);
    border-color: var(--accent-light);
}

.metric-interaction {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border-color: #bfdbfe;
}

.metric-label {
    font-size: 0.6875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 0.375rem;
    font-weight: 600;
}

.metric-value {
    font-weight: 700;
    color: var(--primary);
    font-size: 1.125rem;
}

/* ========================================
   DATA TABLE
   ======================================== */

.table-container {
    overflow-x: auto;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    background: white;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
    text-align: left;
}

.data-table th,
.data-table td {
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
}

.data-table th {
    background: linear-gradient(180deg, var(--bg-subtle) 0%, #f8fafc 100%);
    font-weight: 600;
    color: var(--text-secondary);
    position: sticky;
    top: 0;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
}

.data-table tbody tr {
    transition: all var(--transition-fast);
}

.data-table tbody tr:nth-child(even) {
    background: rgba(248, 250, 252, 0.5);
}

.data-table tbody tr:hover {
    background: var(--bg-hover);
    box-shadow: inset 0 0 0 1px var(--accent-light);
    transform: scale(1.01);
}

.data-table tbody tr:last-child td {
    border-bottom: none;
}

/* ========================================
   EXPLANATION SECTION
   ======================================== */

.explanation-section {
    padding: 1rem 0;
}

.explanation-section h3 {
    font-size: 1.125rem;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.explanation-section h3:first-child {
    margin-top: 0;
}

.explanation-section p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.7;
}

.explanation-section ul {
    list-style-type: none;
    margin-left: 0;
    margin-bottom: 1.5rem;
}

.explanation-section li {
    margin-bottom: 0.75rem;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
    line-height: 1.6;
    transition: all var(--transition-fast);
}

.explanation-section li:hover {
    color: var(--primary);
    transform: translateX(4px);
}

.explanation-section li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: bold;
}

/* ========================================
   UPLOAD AREA
   ======================================== */

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-xl);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-slow);
    background: var(--bg-subtle);
    position: relative;
    overflow: hidden;
}

.upload-area::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, transparent 0%, rgba(59, 130, 246, 0.05) 100%);
    opacity: 0;
    transition: opacity var(--transition-slow);
}

.upload-area:hover {
    border-color: var(--accent);
    background: #eff6ff;
    transform: scale(1.02);
    box-shadow: var(--shadow-md);
}

.upload-area:hover::before {
    opacity: 1;
}

.upload-area.dragover {
    border-color: var(--accent);
    background: linear-gradient(135deg, #dbeafe 0%, #eff6ff 100%);
    border-style: solid;
    box-shadow: var(--shadow-lg), inset 0 0 20px rgba(59, 130, 246, 0.1);
}

.upload-icon {
    font-size: 3rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
    animation: floatUpDown 3s ease-in-out infinite;
}

@keyframes floatUpDown {

    0%,
    100% {
        transform: translateY(0px);
    }

    50% {
        transform: translateY(-10px);
    }
}

.progress-container {
    margin-top: 1.5rem;
    background: var(--bg-subtle);
    border-radius: 999px;
    height: 8px;
    overflow: hidden;
    display: none;
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1);
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--accent) 0%, var(--accent-light) 100%);
    width: 0%;
    transition: width var(--transition-slow);
    position: relative;
    overflow: hidden;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.4), transparent);
    animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
    0% {
        transform: translateX(-100%);
    }

    100% {
        transform: translateX(100%);
    }
}

/* ========================================
   UTILITIES
   ======================================== */

.hidden {
    display: none !important;
}

.text-center {
    text-align: center;
}

.mt-2 {
    margin-top: 0.5rem;
}

.mt-4 {
    margin-top: 1rem;
}

.mb-4 {
    margin-bottom: 1rem;
}

.py-4 {
    padding-top: 1rem;
    padding-bottom: 1rem;
}

/* ========================================
   ALERTS
   ======================================== */

.alert {
    padding: 1rem 1.25rem;
    border-radius: var(--radius-md);
    margin: 1rem 0;
    font-weight: 500;
    border-left: 4px solid;
    animation: slideInAlert var(--transition-base);
}

@keyframes slideInAlert {
    from {
        opacity: 0;
        transform: translateX(-10px);
    }

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

.alert-error {
    background: linear-gradient(135deg, #fef2f2 0%, #fee2e2 100%);
    color: #991b1b;
    border-color: #ef4444;
}

.alert-success {
    background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
    color: #166534;
    border-color: #22c55e;
}

/* ========================================
   LOADING
   ======================================== */

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(8px);
    z-index: 2000;
    display: none;
    align-items: center;
    justify-content: center;
    flex-direction: column;
}

/* ========================================
   CUSTOM UI ELEMENTS
   ======================================== */

.copy-tip {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: normal;
    margin-left: 0.5rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.copy-tip:hover {
    color: var(--accent);
    text-decoration: underline;
    transform: scale(1.05);
}

.icon-xs {
    width: 14px;
    height: 14px;
    vertical-align: middle;
    margin-bottom: 2px;
}

/* Weight Inputs Styling */
.weight-inputs-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
}

.weight-input-group {
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
}

.weight-input-group label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    font-weight: 600;
    margin-bottom: 0;
}

input[type="number"].input-sm,
.input-sm {
    width: 100%;
    padding: 0.625rem 0.75rem;
    background: #ffffff;
    border: 2px solid #cbd5e1;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    color: var(--text-primary);
    transition: all var(--transition-base);
    outline: none;
    font-family: inherit;
}

input[type="number"].input-sm:hover,
.input-sm:hover {
    border-color: #94a3b8;
    box-shadow: 0 0 0 1px #94a3b8;
}

input[type="number"].input-sm:focus,
.input-sm:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
    transform: translateY(-2px);
}

/* Remove spinner from number inputs */
input[type="number"].input-sm::-webkit-inner-spin-button,
input[type="number"].input-sm::-webkit-outer-spin-button {
    -webkit-appearance: none;
    appearance: none;
    margin: 0;
}

input[type="number"].input-sm {
    -moz-appearance: textfield;
    appearance: textfield;
}

.card-subtle {
    background: linear-gradient(135deg, var(--bg-subtle) 0%, rgba(241, 245, 249, 0.6) 100%);
    border: 1px solid var(--border-color);
    padding: 1.25rem;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
}

.card-subtle:hover {
    box-shadow: var(--shadow-sm);
}

.range-container {
    padding: 0.5rem 0;
}

.range-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 6px;
    background: #cbd5e1;
    border-radius: 999px;
    outline: none;
    margin-top: 0.5rem;
}

.range-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-fast);
}

.range-slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-lg), 0 0 12px var(--accent-glow);
}

.range-slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    border: none;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-fast);
}

.range-slider::-moz-range-thumb:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-lg), 0 0 12px var(--accent-glow);
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--bg-subtle);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-bottom: 1.5rem;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* ========================================
   TAB TRANSITIONS
   ======================================== */

.tab-content {
    animation: fadeInTab 0.4s ease-out;
}

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

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

/* ========================================
   RESPONSIVE
   ======================================== */

@media (max-width: 900px) {
    .app-wrapper {
        flex-direction: column;
    }

    .app-sidebar {
        position: relative;
        width: 100%;
        height: auto;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
        padding: 1.25rem 1rem;
    }

    .sidebar-header {
        margin-bottom: 1rem;
        padding-bottom: 1rem;
    }

    .app-content {
        margin-left: 0;
        padding: 2rem 1.5rem;
    }

    .sidebar-nav {
        flex-direction: row;
        overflow-x: auto;
        gap: 0.5rem;
        padding-bottom: 0.5rem;
    }

    .nav-btn {
        width: auto;
        white-space: nowrap;
        padding: 0.75rem 1rem;
    }

    .nav-btn::before {
        width: 100%;
        height: 3px;
        top: auto;
        bottom: 0;
        transform: scaleX(0);
    }

    .nav-btn:hover {
        transform: translateY(-2px);
    }
}

@media (max-width: 640px) {
    .rec-metrics {
        grid-template-columns: repeat(2, 1fr);
    }

    h1 {
        font-size: 1.875rem;
    }

    h2 {
        font-size: 1.375rem;
    }

    .card {
        padding: 1.5rem;
    }

    .app-content {
        padding: 1.5rem 1rem;
    }

    .weight-inputs-container {
        grid-template-columns: 1fr;
    }
}