/* Modern responsive styling for Lung Capacity Physics Simulation */

:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --primary-light: #eff6ff;
    --secondary: #0ea5e9;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --purple: #7c3aed;
    --bg-main: #f8fafc;
    --card-bg: #ffffff;
    --border-color: #e2e8f0;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.6;
    padding-bottom: 60px;
    -webkit-font-smoothing: antialiased;
}

/* Container */
.container {
    max-width: 1240px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header.app-header {
    background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    color: #ffffff;
    padding: 24px 0 20px;
    border-bottom: 3px solid var(--primary);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.title-badge {
    display: inline-block;
    background: rgba(37, 99, 235, 0.3);
    color: #93c5fd;
    border: 1px solid rgba(147, 197, 253, 0.4);
    font-size: 12px;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 9999px;
    margin-bottom: 8px;
    letter-spacing: 0.5px;
}

h1.app-title {
    font-size: 26px;
    font-weight: 800;
    letter-spacing: -0.5px;
    color: #f8fafc;
}

p.app-subtitle {
    font-size: 14px;
    color: #94a3b8;
    margin-top: 4px;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.btn-pill {
    background: rgba(255, 255, 255, 0.1);
    color: #e2e8f0;
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 8px 16px;
    border-radius: 9999px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.btn-pill:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #ffffff;
    transform: translateY(-1px);
}

/* Nav Tabs */
.nav-tabs-wrapper {
    background: #ffffff;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.nav-tabs {
    display: flex;
    gap: 8px;
    overflow-x: auto;
    padding: 8px 0;
}

.nav-tab-btn {
    padding: 8px 16px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 600;
    border-radius: 6px;
    cursor: pointer;
    white-space: nowrap;
    transition: all 0.2s ease;
}

.nav-tab-btn:hover {
    color: var(--primary);
    background: var(--primary-light);
}

.nav-tab-btn.active {
    color: var(--primary);
    background: var(--primary-light);
    border-bottom: 2px solid var(--primary);
}

/* Main Grid Layout */
.main-content {
    margin-top: 24px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 28px;
}

/* Card Common */
.card {
    background: var(--card-bg);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.03);
    padding: 24px;
    margin-bottom: 24px;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 18px;
    padding-bottom: 14px;
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
    gap: 10px;
}

.card-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 8px;
}

.badge {
    padding: 3px 8px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
}

.badge-primary { background: #dbeafe; color: #1d4ed8; }
.badge-success { background: #d1fae5; color: #047857; }
.badge-warning { background: #fef3c7; color: #b45309; }
.badge-purple { background: #ede9fe; color: #6d28d9; }

/* Simulation Section Layout */
.sim-grid {
    display: grid;
    grid-template-columns: 1fr 340px;
    gap: 20px;
}

@media (max-width: 1024px) {
    .sim-grid {
        grid-template-columns: 1fr;
    }
}

.canvas-container {
    position: relative;
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: inset 0 2px 6px rgba(0, 0, 0, 0.03);
    display: flex;
    align-items: center;
    justify-content: center;
}

canvas#sim-canvas {
    width: 100%;
    height: 520px;
    display: block;
    cursor: crosshair;
}

.canvas-controls-overlay {
    position: absolute;
    top: 12px;
    right: 12px;
    display: flex;
    gap: 8px;
    z-index: 10;
}

.toggle-chip {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    font-size: 12px;
    font-weight: 600;
    color: var(--text-main);
    padding: 6px 12px;
    border-radius: 6px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: all 0.2s ease;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.toggle-chip:hover {
    background: #ffffff;
    border-color: var(--primary);
}

.toggle-chip.active {
    background: var(--primary);
    color: #ffffff;
    border-color: var(--primary);
}

/* Control Panel Sidebar */
.control-sidebar {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.control-group {
    background: #f8fafc;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 16px;
}

.control-group-title {
    font-size: 13px;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-muted);
    letter-spacing: 0.5px;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 6px;
}

/* Blow Action Buttons */
.btn-blow {
    width: 100%;
    padding: 18px 20px;
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: #ffffff;
    border: none;
    border-radius: 10px;
    font-size: 18px;
    font-weight: 700;
    cursor: pointer;
    box-shadow: 0 4px 14px rgba(37, 99, 235, 0.35);
    transition: all 0.15s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    user-select: none;
    -webkit-user-select: none;
}

.btn-blow:hover {
    background: linear-gradient(135deg, #1d4ed8 0%, #1e40af 100%);
    box-shadow: 0 6px 18px rgba(37, 99, 235, 0.45);
    transform: translateY(-1px);
}

.btn-blow:active, .btn-blow.blowing {
    background: linear-gradient(135deg, #0284c7 0%, #0369a1 100%);
    box-shadow: 0 2px 6px rgba(2, 132, 199, 0.4);
    transform: translateY(2px) scale(0.98);
    animation: pulseGlow 0.8s infinite alternate;
}

@keyframes pulseGlow {
    0% { box-shadow: 0 0 10px rgba(14, 165, 233, 0.5); }
    100% { box-shadow: 0 0 25px rgba(14, 165, 233, 0.85); }
}

.mic-toggle-btn {
    width: 100%;
    padding: 12px 16px;
    background: #ffffff;
    border: 2px dashed var(--primary);
    border-radius: 8px;
    color: var(--primary);
    font-size: 14px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-bottom: 10px;
}

.mic-toggle-btn:hover {
    background: var(--primary-light);
}

.mic-toggle-btn.active {
    background: #ef4444;
    border: 2px solid #dc2626;
    color: #ffffff;
    animation: micBlink 1.5s infinite;
}

@keyframes micBlink {
    0% { box-shadow: 0 0 0 0 rgba(239, 68, 68, 0.6); }
    70% { box-shadow: 0 0 0 8px rgba(239, 68, 68, 0); }
    100% { box-shadow: 0 0 0 0 rgba(239, 68, 68, 0); }
}

.mic-visualizer {
    margin-top: 8px;
    background: #e2e8f0;
    height: 10px;
    border-radius: 5px;
    overflow: hidden;
    position: relative;
}

.mic-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #10b981 0%, #f59e0b 70%, #ef4444 100%);
    transition: width 0.05s linear;
}

.mic-threshold-line {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 25%;
    width: 2px;
    background: #0f172a;
    z-index: 2;
}

/* Quick volume buttons */
.quick-buttons {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    margin-top: 10px;
}

.btn-secondary-sm {
    padding: 8px;
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-main);
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
}

.btn-secondary-sm:hover {
    background: #f1f5f9;
    border-color: #cbd5e1;
}

/* Stage switch buttons */
.stage-selector {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.stage-btn {
    padding: 10px 12px;
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-main);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.2s ease;
    text-align: left;
}

.stage-btn:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.stage-btn.active {
    background: var(--primary-light);
    border-color: var(--primary);
    color: var(--primary);
}

/* Sliders */
.slider-container {
    margin-bottom: 12px;
}

.slider-label-row {
    display: flex;
    justify-content: space-between;
    font-size: 13px;
    font-weight: 600;
    margin-bottom: 6px;
}

.slider-val {
    color: var(--primary);
    font-family: var(--font-mono);
}

input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: #cbd5e1;
    outline: none;
    cursor: pointer;
    accent-color: var(--primary);
}

/* Readout summary box */
.metric-box {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.metric-item {
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px 12px;
    text-align: center;
}

.metric-label {
    font-size: 11px;
    color: var(--text-muted);
    font-weight: 600;
    margin-bottom: 4px;
}

.metric-value {
    font-size: 16px;
    font-weight: 800;
    color: var(--text-main);
    font-family: var(--font-mono);
}

.metric-highlight {
    color: var(--primary);
}

/* Problem Statement & Solution Cards */
.problem-card {
    background: #ffffff;
    border-left: 4px solid var(--primary);
}

.problem-img-container {
    margin: 16px 0;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    text-align: center;
    background: #fafafa;
    padding: 10px;
}

.problem-img-container img {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
}

.derivation-step {
    background: #f8fafc;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 16px 20px;
    margin-bottom: 16px;
}

.step-num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    background: var(--primary);
    color: #ffffff;
    border-radius: 50%;
    font-size: 12px;
    font-weight: 700;
    margin-right: 8px;
}

.formula-display {
    background: #ffffff;
    border: 1px solid #cbd5e1;
    border-radius: 6px;
    padding: 12px 16px;
    margin: 12px 0;
    font-family: var(--font-mono);
    font-size: 15px;
    color: #1e293b;
    overflow-x: auto;
}

.formula-callout {
    background: #eff6ff;
    border: 1px solid #bfdbfe;
    border-radius: 8px;
    padding: 14px 18px;
    margin: 14px 0;
}

.formula-callout-title {
    font-weight: 700;
    color: #1e40af;
    font-size: 14px;
    margin-bottom: 6px;
}

/* Sandbox Grid */
.sandbox-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 768px) {
    .sandbox-grid {
        grid-template-columns: 1fr;
    }
}

/* Misconceptions Grid */
.pitfall-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 16px;
}

.pitfall-card {
    border-radius: 8px;
    border: 1px solid #fee2e2;
    background: #fff5f5;
    padding: 16px;
}

.pitfall-header {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #dc2626;
    font-weight: 700;
    font-size: 14px;
    margin-bottom: 8px;
}

.pitfall-fix {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px dashed #fca5a5;
    color: #065f46;
    font-size: 13px;
}

/* Quiz Section */
.quiz-card {
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 16px;
    margin-bottom: 14px;
}

.quiz-question {
    font-weight: 700;
    font-size: 15px;
    margin-bottom: 12px;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.quiz-opt-btn {
    padding: 10px 14px;
    border: 1px solid var(--border-color);
    background: #f8fafc;
    border-radius: 6px;
    text-align: left;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s;
}

.quiz-opt-btn:hover {
    background: #f1f5f9;
    border-color: #cbd5e1;
}

.quiz-opt-btn.correct {
    background: #d1fae5;
    border-color: #10b981;
    color: #065f46;
    font-weight: 700;
}

.quiz-opt-btn.incorrect {
    background: #fee2e2;
    border-color: #ef4444;
    color: #991b1b;
}

.quiz-explanation {
    margin-top: 10px;
    padding: 10px;
    border-radius: 6px;
    background: #eff6ff;
    border: 1px solid #bfdbfe;
    font-size: 13px;
    color: #1e40af;
    display: none;
}

.quiz-explanation.show {
    display: block;
}

/* Footer */
footer.app-footer {
    text-align: center;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 13px;
}