/* ==========================================================================
   LAYOUT — Reset & structure générale
   ========================================================================== */

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

/* L'attribut HTML `hidden` doit toujours primer sur tout autre `display`. */
[hidden] { display: none !important; }

html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    overflow: hidden;
}

body {
    font-family: var(--font-sans);
    font-size: var(--fs-md);
    color: var(--text-primary);
    background: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background var(--t-base), color var(--t-base);
}

h1, h2, h3, h4, h5, h6 { margin: 0; font-weight: 600; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

button { font-family: inherit; cursor: pointer; }

/* Structure de l'application */
.app {
    display: grid;
    grid-template-rows: var(--header-height) 1fr var(--footer-height);
    height: 100vh;
    width: 100vw;
}

/* En-tête */
.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--sp-6);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-subtle);
    box-shadow: var(--shadow-xs);
    z-index: 10;
}

.brand {
    display: flex;
    align-items: center;
    gap: var(--sp-3);
}

.brand-logo {
    height: 1.8rem;
    width: auto;
    object-fit: contain;
}

.brand h1 {
    font-size: var(--fs-lg);
    letter-spacing: -0.01em;
}

.toolbar {
    display: flex;
    align-items: center;
    gap: var(--sp-2);
}

.divider {
    width: 1px;
    height: 24px;
    background: var(--border-subtle);
    margin: 0 var(--sp-2);
}

/* Workspace - 2 panneaux + splitter */
.workspace {
    display: grid;
    grid-template-columns: 1fr 6px 1fr;
    overflow: hidden;
    background: var(--bg-primary);
}

.panel {
    display: flex;
    flex-direction: column;
    overflow: hidden;
    background: var(--bg-secondary);
    min-width: 0;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--sp-3) var(--sp-4);
    border-bottom: 1px solid var(--border-subtle);
    background: var(--bg-secondary);
    flex-shrink: 0;
}

.panel-header h2 {
    font-size: var(--fs-sm);
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: flex;
    align-items: center;
    gap: var(--sp-2);
}

.panel-header h2 i {
    color: var(--accent);
    font-size: var(--fs-md);
}

.panel-header-actions {
    display: flex;
    gap: var(--sp-1);
}

.panel-body {
    flex: 1;
    overflow: hidden;
    position: relative;
    display: flex;
    flex-direction: column;
}

/* Splitter */
.splitter {
    background: var(--border-subtle);
    cursor: col-resize;
    transition: background var(--t-fast);
    position: relative;
}

.splitter:hover,
.splitter.dragging {
    background: var(--accent);
}

.splitter::after {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 4px;
    height: 32px;
    border-radius: 2px;
    background: var(--border-strong);
    opacity: 0;
    transition: opacity var(--t-fast);
}

.splitter:hover::after { opacity: 0.5; }

/* Footer */
.app-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--sp-6);
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-subtle);
    font-size: var(--fs-xs);
    color: var(--text-tertiary);
}

.app-footer i { margin-right: var(--sp-1); }

.diagram-info { font-family: var(--font-mono); }

/* Responsive */
@media (max-width: 768px) {
    .workspace {
        grid-template-columns: 1fr;
        grid-template-rows: 1fr 6px 1fr;
    }
    .splitter { cursor: row-resize; }
    .toolbar .btn span { display: none; }
}