/* ==========================================================================
   Design System — Learn-Level Framework
   Themes: Modern Minimal (default) | Clinical (dark)
   ========================================================================== */

/* ===== CSS Custom Properties — Modern Minimal (Light) ===== */
:root {
    font-size: var(--font-size-base, 16px);

    /* Surfaces */
    --bg-primary: #f5f7fa;
    --bg-secondary: #ffffff;
    --bg-tertiary: #eef1f6;
    --bg-panel: #ffffff;
    --bg-hover: #e8ecf2;
    --bg-active: #dce3ed;
    --bg-overlay: rgba(15, 23, 42, 0.4);

    /* Borders */
    --border-color: #dfe4ec;
    --border-active: #4361ee;
    --border-hover: #c5cdd8;

    /* Text */
    --text-primary: #1a1a2e;
    --text-secondary: #3d4663;
    --text-muted: #6b7a99;
    --text-dim: #94a3b8;

    /* Accent */
    --accent-blue: #4361ee;
    --accent-blue-light: #6b83f2;
    --accent-blue-bg: rgba(67, 97, 238, 0.08);
    --accent-green: #22c55e;
    --accent-green-bg: rgba(34, 197, 94, 0.08);
    --accent-red: #ef4444;
    --accent-red-bg: rgba(239, 68, 68, 0.08);
    --accent-amber: #f59e0b;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-card-hover: 0 4px 16px rgba(0, 0, 0, 0.10);

    /* Radii */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-xl: 20px;
    --radius-full: 9999px;

    /* Spacing scale */
    --space-xs: 8px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;

    /* Top bar */
    --top-bar-bg: rgba(255, 255, 255, 0.85);
    --top-bar-border: #e2e8f0;

    /* Scrollbar */
    --scrollbar-thumb: #c5cdd8;
    --scrollbar-thumb-hover: #94a3b8;

    /* Misc */
    --qr-bg: #ffffff;
}

/* ===== Clinical Theme (Dark) ===== */
[data-theme="clinical"] {
    /* Surfaces */
    --bg-primary: #0c1524;
    --bg-secondary: #132035;
    --bg-tertiary: #1a2944;
    --bg-panel: #132035;
    --bg-hover: #1e3150;
    --bg-active: #243a5c;
    --bg-overlay: rgba(0, 0, 0, 0.5);

    /* Borders */
    --border-color: #1e3350;
    --border-active: #0ea5e9;
    --border-hover: #2a4468;

    /* Text */
    --text-primary: #e8eff8;
    --text-secondary: #b0c4de;
    --text-muted: #6d8aad;
    --text-dim: #4a6585;

    /* Accent */
    --accent-blue: #0ea5e9;
    --accent-blue-light: #38bdf8;
    --accent-blue-bg: rgba(14, 165, 233, 0.12);
    --accent-green: #34d399;
    --accent-green-bg: rgba(52, 211, 153, 0.12);
    --accent-red: #f87171;
    --accent-red-bg: rgba(248, 113, 113, 0.12);
    --accent-amber: #fbbf24;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.4);
    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(255, 255, 255, 0.03);
    --shadow-card-hover: 0 4px 16px rgba(0, 0, 0, 0.35);

    /* Top bar */
    --top-bar-bg: rgba(12, 21, 36, 0.9);
    --top-bar-border: #1e3350;

    /* Scrollbar */
    --scrollbar-thumb: #1e3350;
    --scrollbar-thumb-hover: #2a4468;

    /* Misc */
    --qr-bg: #ffffff;
}

/* ===== Screen Reader Only ===== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ===== Skip Link ===== */
.skip-link {
    position: absolute;
    top: -100%;
    left: var(--space-md);
    z-index: 1000;
    padding: var(--space-sm) var(--space-md);
    background: var(--accent-blue);
    color: #ffffff;
    border-radius: 0 0 var(--radius-sm) var(--radius-sm);
    font-weight: 600;
    font-size: 0.88rem;
    text-decoration: none;
    transition: top 0.2s ease;
}

.skip-link:focus {
    top: 0;
}

/* ===== Base Reset ===== */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    overflow-x: hidden;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ===== Top Bar ===== */
.top-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: var(--top-bar-bg);
    border-bottom: 1px solid var(--top-bar-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transition: all 0.3s ease;
}

.top-bar-main {
    display: flex;
    align-items: center;
    height: var(--top-bar-height);
    padding: 0 var(--space-md);
    max-width: 1200px;
    margin: 0 auto;
}

.top-bar-left,
.top-bar-right {
    flex: 0 0 48px;
    display: flex;
    align-items: center;
}

.top-bar-left {
    justify-content: flex-start;
}

.top-bar-right {
    justify-content: flex-end;
}

.top-bar-center {
    flex: 1;
    text-align: center;
}

.top-bar-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--accent-blue);
    letter-spacing: 1px;
}

/* Settings button */
.top-bar .settings-btn {
    position: static;
    width: 34px;
    height: 34px;
    border-radius: var(--radius-full);
    background: transparent;
    color: var(--text-muted);
    border: none;
    font-size: 1.15rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
}

.top-bar .settings-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

/* Progress row in top bar */
.top-bar-progress {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: 4px var(--space-md) 6px;
    max-width: 1200px;
    margin: 0 auto;
}

.top-bar-progress .learning-progress-bar {
    flex: 1;
    min-width: 0;
}

.top-bar-progress .learning-progress-text {
    flex-shrink: 0;
}

/* Free mode badge */
.free-mode-badge {
    display: none;
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--accent-amber);
    background: rgba(245, 158, 11, 0.1);
    border: 1px solid rgba(245, 158, 11, 0.25);
    padding: 1px 8px;
    border-radius: var(--radius-full);
    white-space: nowrap;
    flex-shrink: 0;
}

.free-mode-badge.active {
    display: inline-block;
}

/* ===== App Layout ===== */
.app-layout {
    min-height: 100vh;
    transition: padding-top 0.4s ease;
}

.content-area {
    max-width: 1000px;
    margin: 0 auto;
    padding: var(--space-lg) var(--space-md);
    min-height: calc(100vh - var(--top-bar-height));
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: var(--radius-full); }
::-webkit-scrollbar-thumb:hover { background: var(--scrollbar-thumb-hover); }

/* ===== Shared Animations ===== */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes scalePop {
    0% { transform: scale(0.3); opacity: 0; }
    70% { transform: scale(1.1); }
    100% { transform: scale(1); opacity: 1; }
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .top-bar-title {
        font-size: 0.95rem;
    }

    .content-area {
        padding: var(--space-md) var(--space-sm);
    }
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}