:root {
    --bg-dark: #0a0f1d;
    --panel-dark: #161e31;
    --glass-bg: rgba(30, 41, 59, 0.7);
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --accent: #38bdf8;
    --accent-glow: rgba(56, 189, 248, 0.4);
    --accent-hover: #0ea5e9;
    --danger: #f43f5e;
    --border: rgba(51, 65, 85, 0.5);
    --font-family: 'Outfit', sans-serif;
    --card-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3), 0 8px 10px -6px rgba(0, 0, 0, 0.3);
}

body {
    background: radial-gradient(circle at top left, #1e293b 0%, #0a0f1d 100%);
    color: var(--text-main);
    font-family: var(--font-family);
    margin: 0;
    padding: 20px;
    height: 100vh;
    box-sizing: border-box;
    overflow: hidden;
}

.app-container {
    max-width: 1600px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    flex-direction: column;
}

header {
    margin-bottom: 20px;
    text-align: center;
}

header h1 {
    margin: 0;
    font-size: 2rem;
    background: linear-gradient(to right, #38bdf8, #818cf8);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle {
    color: var(--text-muted);
    margin: 5px 0 0;
    font-size: 0.9rem;
    letter-spacing: 1px;
}

main {
    display: grid;
    grid-template-columns: 400px 1fr;
    gap: 30px;
    flex: 1;
    overflow: hidden;
}

/* Input Panel */
.input-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 25px;
    border-radius: 20px;
    border: 1px solid var(--border);
    overflow-y: auto;
    max-height: calc(100vh - 120px);
    box-shadow: var(--card-shadow);
}

h2 {
    font-size: 1rem;
    text-transform: uppercase;
    color: var(--text-muted);
    border-bottom: 2px solid var(--border);
    padding-bottom: 10px;
    margin-top: 0;
    margin-bottom: 15px;
}

.form-group {
    margin-bottom: 12px;
}

.form-row {
    display: flex;
    gap: 15px;
}

.form-row .form-group {
    flex: 1;
}

label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 5px;
}

.form-entry {
    display: grid;
    grid-template-columns: 1fr 100px 70px;
    align-items: center;
    gap: 15px;
    margin-bottom: 12px;
}

.form-entry label {
    display: inline-block;
    margin-bottom: 0;
    line-height: 1.2;
}

.form-entry input, 
.form-entry select {
    text-align: right;
    padding: 6px 10px;
}

.form-entry .unit-label,
.form-entry .unit-label-small,
.form-entry .unit-weight,
.form-entry .unit-pressure,
.form-entry .unit-force-strap {
    font-size: 0.75rem;
    color: var(--accent);
    white-space: nowrap;
}

input,
select {
    width: 100%;
    background: #0f172a;
    border: 1px solid var(--border);
    color: var(--text-main);
    padding: 8px 12px;
    border-radius: 6px;
    font-family: inherit;
    font-size: 0.9rem;
    box-sizing: border-box;
    transition: 0.2s;
}

input:focus,
select:focus {
    outline: none;
    border-color: var(--accent);
}

/* Layer Items */
.layer-item {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border);
    padding: 12px;
    border-radius: 10px;
    margin-bottom: 10px;
}

.layer-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 0.8rem;
    color: var(--accent);
    font-weight: 600;
}

.remove-layer {
    background: none;
    border: none;
    color: var(--danger);
    cursor: pointer;
    font-size: 1.2rem;
    line-height: 0.5;
}

.hidden {
    display: none !important;
}

/* Buttons */
.btn-secondary {
    width: 100%;
    padding: 10px;
    background: transparent;
    border: 2px dashed var(--border);
    color: var(--text-muted);
    border-radius: 8px;
    cursor: pointer;
    margin-bottom: 20px;
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.btn-toggle {
    padding: 8px 16px;
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-muted);
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-toggle.active {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
}

.unit-toggle-container {
    display: flex;
    align-items: center;
    gap: 8px;
    background: rgba(0, 0, 0, 0.2);
    padding: 4px;
    border-radius: 24px;
    border: 1px solid var(--border);
}

.unit-toggle-btn {
    padding: 6px 12px;
    border-radius: 20px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.unit-toggle-btn.active {
    background: var(--accent);
    color: white;
}

/* PDF Export Helpers */
.pdf-export-mode {
    background: white !important;
    color: black !important;
}

.pdf-export-mode .input-panel, 
.pdf-export-mode .result-panel,
.pdf-export-mode .card,
.pdf-export-mode .chart-box {
    background: white !important;
    color: black !important;
    border-color: #ddd !important;
    box-shadow: none !important;
    backdrop-filter: none !important;
}

.pdf-export-mode h1,
.pdf-export-mode h2,
.pdf-export-mode h3,
.pdf-export-mode .subtitle,
.pdf-export-mode label,
.pdf-export-mode .unit {
    color: black !important;
}

.btn-primary {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, var(--accent), #2563eb);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(37, 99, 235, 0.3);
}

.btn-success {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, #22c55e, #15803d);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(34, 197, 94, 0.3);
}

.btn-warning {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, #eab308, #ca8a04);
    /* Yellow-500 to Yellow-600 */
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(234, 179, 8, 0.3);
}

.btn-orange {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, #f97316, #ea580c);
    /* Orange-500 to Orange-600 */
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(249, 115, 22, 0.3);
}

.btn-light {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, #9ca3af, #6b7280);
    /* Gray-400 to Gray-500 */
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(107, 114, 128, 0.3);
}

/* Result Panel */
.result-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 24px;
    border-radius: 20px;
    border: 1px solid var(--border);
    box-shadow: var(--card-shadow);
    overflow-y: auto;
    overflow-x: hidden;
    max-height: calc(100vh - 120px);
}

/* Category Sections */
.category-section {
    margin-bottom: 20px;
    background: var(--panel-dark);
    border-radius: 12px;
    border: 1px solid var(--border);
    overflow: hidden;
}

.category-header {
    padding: 15px 20px;
    background: rgba(255, 255, 255, 0.03);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    user-select: none;
    transition: background 0.2s;
    font-size: 1.2rem;
    color: var(--text-main);
    margin: 0;
}

.category-header:hover {
    background: rgba(255, 255, 255, 0.05);
}

.category-header .arrow {
    font-size: 0.8em;
    transition: transform 0.3s ease;
    width: 20px;
    display: inline-block;
    text-align: center;
}

.category-section.collapsed .category-header .arrow {
    transform: rotate(-90deg);
}

.category-content {
    padding: 20px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    transition: max-height 0.3s ease-out, padding 0.3s ease;
    max-height: 2000px;
    /* Arbitrary large max-height */
}

.category-section.collapsed .category-content {
    max-height: 0;
    padding-top: 0;
    padding-bottom: 0;
    overflow: hidden;
    visibility: hidden;
}

/* Info Cards (Coming Soon) */
.tool-card.coming-soon {
    opacity: 0.7;
    border-style: dashed;
    cursor: default;
}

.tool-card.coming-soon:hover {
    transform: none;
    box-shadow: none;
    border-color: var(--border);
}

.tool-card.coming-soon .tool-title {
    color: var(--text-muted);
}

.summary-cards {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 20px;
}

.card {
    background: rgba(15, 23, 42, 0.4);
    padding: 18px;
    border-radius: 14px;
    text-align: center;
    border: 1px solid var(--border);
    transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.4);
    border-color: var(--accent);
}


.card.highlight {
    border-color: var(--accent);
    background: rgba(56, 189, 248, 0.1);
}

.card h3 {
    margin: 0;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.card .value {
    font-size: 1.8rem;
    font-weight: 600;
    margin: 5px 0;
}

/* Charts */
.charts-row {
    display: flex;
    gap: 20px;
    height: 500px;
    /* Explicit height to stop extrusion */
    width: 100%;
    margin-bottom: 20px;
}

.chart-box {
    background: rgba(15, 23, 42, 0.3);
    border-radius: 12px;
    padding: 10px;
    display: flex;
    flex-direction: column;
    height: 100%;
    position: relative;
    /* Allow scrolling for deep profiles */
    overflow-y: auto;
    overflow-x: hidden;
    min-width: 0;
}

.chart-box h4 {
    margin: 0 0 10px 0;
    color: var(--text-muted);
    font-size: 0.9rem;
    text-align: center;
    flex: 0 0 auto;
}

.chart-container-wrapper {
    flex: 1;
    position: relative;
    min-height: 0;
    width: 100%;
}

.chart-box canvas {
    display: block;
    width: 100% !important;
    max-width: 100%;
    /* Remove height: 100% !important to allow dynamic sizing */
}

.small {
    flex: 1;
}

.large {
    flex: 2;
}

/* Input alignment */
.input-wrapper {
    display: flex;
    align-items: center;
    gap: 10px;
}

.input-wrapper input {
    flex: 1;
    width: auto;
    /* Override 100% */
}

.unit {
    color: var(--text-muted);
    font-size: 0.9rem;
    white-space: nowrap;
    min-width: 30px;
}

/* Header Toggle */
.header-actions {
    position: absolute;
    top: 20px;
    right: 20px;
}