/* ===========================
   CSS 變數
   =========================== */
:root {
    --primary: #8b5cf6;
    /* Violet 500 - L2 Ridge Theme */
    --primary-light: #a78bfa;
    --primary-dark: #7c3aed;

    --secondary: #ec4899;
    /* Pink 500 - L1 Lasso Theme */
    --secondary-light: #f472b6;

    --accent: #f59e0b;
    /* Amber 500 */

    --bg-start: #0f172a;
    /* Slate 900 */
    --bg-end: #1e293b;
    /* Slate 800 */
    --surface: rgba(30, 41, 59, 0.7);
    --surface-hover: rgba(51, 65, 85, 0.8);

    --text-main: #f1f5f9;
    --text-muted: #94a3b8;

    --glass-border: rgba(255, 255, 255, 0.1);
    --radius: 12px;
    --shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
}

body {
    font-family: 'Noto Sans TC', sans-serif;
    background: linear-gradient(135deg, var(--bg-start), var(--bg-end));
    color: var(--text-main);
    margin: 0;
    min-height: 100vh;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: rgba(255, 255, 255, 0.03);
    border-radius: var(--radius);
    border: 1px solid var(--glass-border);
    backdrop-filter: blur(10px);
}

.header h1 {
    margin: 0;
    background: linear-gradient(to right, #c084fc, #f472b6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 2.5rem;
}

.subtitle {
    color: var(--text-muted);
    margin-top: 0.5rem;
}

/* Layout */
.main-content {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

/* Visualization Section */
.visualization-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.canvas-container {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1rem;
    height: 400px;
    /* Chart area height */
    position: relative;
    border: 1px solid var(--glass-border);
}

.weights-visual {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1rem;
    border: 1px solid var(--glass-border);
}

.weights-chart {
    height: 205px;
    position: relative;
}

.weights-summary {
    margin: 0.75rem 0 0;
    color: var(--text-main);
    font-size: 0.85rem;
    line-height: 1.5;
    font-variant-numeric: tabular-nums;
}

.weights-visual h3 {
    margin: 0 0 1rem 0;
    font-size: 1rem;
    color: var(--text-muted);
}

canvas {
    width: 100% !important;
    height: 100% !important;
}

/* Control Section */
.control-section {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.card {
    background: var(--surface);
    padding: 1.2rem;
    border-radius: var(--radius);
    border: 1px solid var(--glass-border);
}

.card h3 {
    margin-top: 0;
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Highlight Card for Regularization controls */
.highlight-card {
    background: linear-gradient(145deg, rgba(139, 92, 246, 0.1), rgba(236, 72, 153, 0.05));
    border: 1px solid rgba(139, 92, 246, 0.3);
}

/* Controls */
.control-group {
    margin-bottom: 1.2rem;
}

.control-group label {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.control-group label span {
    font-feature-settings: "tnum";
    font-weight: bold;
    color: var(--primary-light);
}

input[type="range"] {
    width: 100%;
    accent-color: var(--primary);
    cursor: pointer;
}

.hint {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin: 0.3rem 0 0 0;
    line-height: 1.4;
}

/* Radio Buttons for Reg Type */
.reg-type-selector {
    display: flex;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 8px;
    padding: 4px;
    margin-bottom: 1rem;
}

.radio-label {
    flex: 1;
    text-align: center;
    cursor: pointer;
    position: relative;
    z-index: 1;
}

.radio-label input {
    display: none;
}

.radio-label span {
    display: block;
    padding: 8px 4px;
    font-size: 0.85rem;
    border-radius: 6px;
    transition: all 0.3s;
    color: var(--text-muted);
}

.radio-label input:checked+span {
    background: var(--primary);
    color: white;
    font-weight: 500;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

/* Specific colors for types */
.radio-label input[value="l1"]:checked+span {
    background: var(--secondary);
}

.radio-label input[value="l2"]:checked+span {
    background: var(--primary);
}

/* Buttons */
button {
    width: 100%;
    padding: 10px;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    margin-bottom: 0.5rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 12px rgba(139, 92, 246, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(139, 92, 246, 0.4);
}

.btn-primary.active {
    background: linear-gradient(135deg, #ef4444, #b91c1c);
    /* Red for stop */
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-main);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.15);
}

.btn-text {
    background: transparent;
    color: var(--text-muted);
    font-weight: normal;
    font-size: 0.9rem;
}

.btn-text:hover {
    color: var(--text-main);
    text-decoration: underline;
}

/* Metrics */
.metrics {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.metric {
    background: rgba(0, 0, 0, 0.2);
    padding: 0.8rem;
    border-radius: 8px;
    text-align: center;
}

.metric span:first-child {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 0.3rem;
}

.metric span:last-child {
    font-family: 'Courier New', monospace;
    font-weight: bold;
    font-size: 1.1rem;
    color: var(--accent);
}

/* Info Section */
.info-section {
    margin-top: 2rem;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.info-card h3 {
    color: var(--primary-light);
    margin-top: 0;
}

.formula-box {
    background: rgba(0, 0, 0, 0.3);
    padding: 10px;
    border-radius: 6px;
    text-align: center;
    font-family: monospace;
    margin: 1rem 0;
    border-left: 3px solid var(--text-muted);
}

.formula-box.primary {
    border-left-color: var(--primary);
    color: var(--primary-light);
}

.formula-box.secondary {
    border-left-color: var(--secondary);
    color: var(--secondary-light);
}

.feature-list {
    padding-left: 1.2rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.feature-list li {
    margin-bottom: 0.5rem;
}

.steps-list {
    padding-left: 1.2rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.steps-list li {
    margin-bottom: 0.5rem;
}

/* Footer */
.footer {
    text-align: center;
    margin-top: 3rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--glass-border);
    color: var(--text-muted);
}

.back-home {
    display: inline-block;
    margin-top: 1rem;
    color: var(--primary-light);
    text-decoration: none;
    transition: color 0.2s;
}

.back-home:hover {
    color: white;
}

/* ... existing styles ... */

.img-container {
    margin-top: 1rem;
    text-align: center;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 8px;
    padding: 10px;
}

.concept-img {
    max-width: 100%;
    height: auto;
    filter: drop-shadow(0 4px 6px rgba(0, 0, 0, 0.3));
    transition: transform 0.3s ease;
}

.concept-img:hover {
    transform: scale(1.05);
}

@media (max-width: 900px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}