/* =========================================
 * DEC DESIGN SYSTEM — 3D Equation Generator
 * ========================================= */
:root {
    --dec-blue-primary: #009FE3;
    --dec-blue-dark: #0077A9;
    --dec-blue-glow: rgba(0, 159, 227, 0.25);

    --dec-orange-safety: #FF671F;
    --dec-orange-dark: #D64B00;

    --dec-dark-bg: #F0F2F5;
    --dec-panel-bg: #FFFFFF;
    --dec-text-main: #111827;
    --dec-text-muted: #6B7280;
    --dec-border: #E5E7EB;
    --dec-border-active: #9CA3AF;

    --font-sans: 'Inter', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    --ease-punch: cubic-bezier(0.34, 1.56, 0.64, 1);
    --shadow-card: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -1px rgba(0,0,0,0.03);
    --shadow-float: 0 20px 25px -5px rgba(0,0,0,0.1), 0 10px 10px -5px rgba(0,0,0,0.04);

    --bg-grid: url('data:image/svg+xml;utf8,<svg width="40" height="40" viewBox="0 0 40 40" xmlns="http://www.w3.org/2000/svg"><circle cx="2" cy="2" r="1" fill="%23cbd5e1" opacity="0.4"/></svg>');
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--dec-dark-bg);
    background-image: var(--bg-grid);
    color: var(--dec-text-main);
    overflow: hidden;
    height: 100vh;
}

/* ---- LAYOUT ---- */
#app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    width: 100vw;
}

/* ---- HEADER / NAVBAR ---- */
#header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--dec-border);
    padding: 0.625rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0;
}

.brand {
    font-size: 1rem;
    font-weight: 900;
    letter-spacing: -0.03em;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.brand-tag {
    background: var(--dec-orange-safety);
    color: white;
    font-family: var(--font-mono);
    font-size: 0.65rem;
    padding: 2px 6px;
    border-radius: 4px;
    transform: rotate(-5deg);
    display: inline-block;
}

.text-blue { color: var(--dec-blue-primary); }
.text-orange { color: var(--dec-orange-safety); }
.font-mono { font-family: var(--font-mono); letter-spacing: -0.04em; }

/* ---- MAIN CONTENT ---- */
#main-content {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* ---- 3D CANVAS ---- */
#canvas-container {
    flex: 1;
    position: relative;
    background: var(--dec-dark-bg);
    background-image: var(--bg-grid);
    overflow: hidden;
}

/* ---- SIDEBAR ---- */
#controls-sidebar {
    width: 380px;
    background: var(--dec-panel-bg);
    border-left: 1px solid var(--dec-border);
    overflow-y: auto;
    flex-shrink: 0;
    scrollbar-width: thin;
    scrollbar-color: var(--dec-border) transparent;
}

/* ---- EQUATION GROUP ---- */
.equation-group {
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--dec-border);
}

.section-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    color: var(--dec-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: 0.5rem;
    display: flex;
    justify-content: space-between;
}

.equation-input-full {
    width: 100%;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--dec-border);
    border-radius: 6px;
    background: var(--dec-dark-bg);
    color: var(--dec-text-main);
    margin-bottom: 0.5rem;
    outline: none;
    transition: border-color 0.2s;
}

.equation-input-full:focus {
    border-color: var(--dec-blue-primary);
    box-shadow: 0 0 0 3px var(--dec-blue-glow);
}

#equation-status {
    margin-bottom: 0.5rem;
    min-height: 1.5rem;
    font-size: 0.75rem;
    font-family: var(--font-mono);
}

#equation-status .status-ok  { color: #16a34a; }
#equation-status .status-err { color: var(--dec-orange-safety); }

.button-group {
    display: flex;
    gap: 0.5rem;
}

/* ---- BUTTONS ---- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1rem;
    font-family: var(--font-sans);
    font-size: 0.8rem;
    font-weight: 700;
    border-radius: 6px;
    border: none;
    cursor: pointer;
    transition: transform 0.1s, box-shadow 0.1s;
    text-decoration: none;
}

.btn:active { transform: scale(0.96); }

.btn-primary {
    background: var(--dec-blue-primary);
    color: white;
    box-shadow: 0 3px 0 var(--dec-blue-dark);
    flex: 1;
}

.btn-primary:active {
    box-shadow: none;
    transform: translateY(3px);
}

.btn-ghost {
    background: transparent;
    border: 1.5px solid var(--dec-border);
    color: var(--dec-text-main);
    flex: 1;
}

.btn-ghost:hover { border-color: var(--dec-text-main); }

/* ---- ACCORDION (flush) ---- */
.accordion-flush { border: none; }

.accordion-flush .accordion-item {
    border-bottom: 1px solid var(--dec-border);
}

.accordion-header {
    width: 100%;
    background: none;
    border: none;
    padding: 0.75rem 1.25rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--dec-text-main);
    letter-spacing: -0.01em;
    transition: background 0.15s;
}

.accordion-header:hover { background: var(--dec-dark-bg); }

.accordion-header::after {
    content: '+';
    font-family: var(--font-mono);
    font-size: 1rem;
    color: var(--dec-text-muted);
    transition: transform 0.2s;
}

.accordion-header.active::after { transform: rotate(45deg); }

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.accordion-content.active { max-height: 600px; }

.accordion-body { padding: 0.75rem 1.25rem 1rem; }

/* ---- SLIDERS ---- */
.param-slider-inline {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.6rem;
}

.param-slider-inline label {
    flex: 0 0 90px;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    color: var(--dec-text-muted);
}

.param-slider-inline input[type="range"] {
    flex: 1;
    accent-color: var(--dec-blue-primary);
    cursor: pointer;
}

.param-value {
    flex: 0 0 48px;
    text-align: right;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    font-weight: 700;
    color: var(--dec-blue-primary);
}

/* ---- TOGGLE ---- */
.toggle-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.4rem 0;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--dec-text-muted);
}

.toggle-switch-wrap {
    position: relative;
    width: 36px;
    height: 20px;
}

.toggle-switch-wrap input { opacity: 0; width: 0; height: 0; }

.toggle-track {
    position: absolute;
    inset: 0;
    background: var(--dec-border);
    border-radius: 20px;
    cursor: pointer;
    transition: background 0.2s;
}

.toggle-track::after {
    content: '';
    position: absolute;
    width: 14px;
    height: 14px;
    background: white;
    border-radius: 50%;
    top: 3px;
    left: 3px;
    transition: transform 0.2s var(--ease-punch);
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.toggle-switch-wrap input:checked + .toggle-track {
    background: var(--dec-blue-primary);
}

.toggle-switch-wrap input:checked + .toggle-track::after {
    transform: translateX(16px);
}

/* ---- EXAMPLES GRID ---- */
.examples-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.4rem;
}

.example-btn {
    width: 100%;
    text-align: left;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    padding: 0.45rem 0.75rem;
    background: var(--dec-dark-bg);
    border: 1px solid var(--dec-border);
    border-radius: 6px;
    color: var(--dec-text-main);
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.example-btn:hover {
    border-color: var(--dec-blue-primary);
    background: #EFF9FF;
}

/* ---- EXPORT / BOTTOM BUTTONS ---- */
.action-row {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.75rem;
}

/* ---- MOBILE FAB ---- */
#mobile-controls-toggle {
    display: none;
    position: fixed;
    bottom: 1.25rem;
    right: 1.25rem;
    z-index: 200;
    width: 52px;
    height: 52px;
    border-radius: 50%;
    background: var(--dec-blue-primary);
    color: white;
    border: none;
    box-shadow: 0 4px 0 var(--dec-blue-dark), var(--shadow-float);
    font-size: 22px;
    cursor: pointer;
    align-items: center;
    justify-content: center;
}

@media (max-width: 768px) {
    #controls-sidebar {
        position: fixed;
        top: 52px;
        right: -420px;
        height: calc(100vh - 52px);
        z-index: 150;
        transition: right 0.3s ease;
        box-shadow: var(--shadow-float);
        width: 90vw;
        max-width: 380px;
    }

    #controls-sidebar.active { right: 0; }

    #mobile-controls-toggle { display: flex; }

    #dim-overlay {
        bottom: 5rem;
        max-width: calc(100vw - 2rem);
    }

    .header-formula { display: none; }
}

/* ---- MODAL ---- */
.modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(17, 24, 39, 0.5);
    backdrop-filter: blur(4px);
    z-index: 300;
    align-items: center;
    justify-content: center;
}

.modal-overlay.show { display: flex; }

.modal {
    background: var(--dec-panel-bg);
    border: 1px solid var(--dec-border);
    border-radius: 12px;
    padding: 2rem;
    max-width: 480px;
    width: 90vw;
    box-shadow: var(--shadow-float);
}

.modal-title {
    font-size: 1.25rem;
    font-weight: 900;
    letter-spacing: -0.03em;
    margin-bottom: 1rem;
}

.modal-title::after {
    content: '';
    display: block;
    width: 32px;
    height: 3px;
    background: var(--dec-orange-safety);
    margin-top: 6px;
}

.modal-content { margin-bottom: 1.25rem; font-size: 0.875rem; color: var(--dec-text-muted); line-height: 1.7; }
.modal-source-link { display: block; font-size: 0.82rem; color: var(--dec-blue-primary); text-decoration: none; margin-bottom: 1rem; }
.modal-source-link:hover { text-decoration: underline; }
.modal-content h3 { color: var(--dec-text-main); font-size: 0.8rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; margin: 0.75rem 0 0.25rem; }
.modal-content code { font-family: var(--font-mono); font-size: 0.78rem; background: var(--dec-dark-bg); padding: 1px 5px; border-radius: 3px; color: var(--dec-blue-primary); }

/* ---- DIMENSION OVERLAY ---- */
#dim-overlay {
    position: fixed;
    bottom: 1rem;
    left: 1rem;
    background: rgba(255, 255, 255, 0.88);
    backdrop-filter: blur(8px);
    border: 1px solid var(--dec-border);
    border-left: 3px solid var(--dec-blue-primary);
    border-radius: 8px;
    padding: 0.5rem 0.75rem;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--dec-text-main);
    line-height: 1.8;
    pointer-events: none;
    z-index: 50;
}

#dim-overlay .dim-label {
    color: var(--dec-text-muted);
    font-size: 0.6rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    display: block;
    margin-bottom: 0.15rem;
}

#dim-overlay .dim-value {
    font-weight: 700;
    color: var(--dec-blue-primary);
}

#dim-overlay .dim-row {
    display: flex;
    gap: 1rem;
}

#dim-overlay .dim-item {
    display: flex;
    flex-direction: column;
}