:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --radius: 12px;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    padding: 2rem 1rem;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

.app-grid {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 2rem;
    align-items: start;
}

@media (max-width: 850px) {
    .app-grid {
        grid-template-columns: 1fr;
    }
}

.controls-panel {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
    background: #f1f5f9;
    padding: 0.4rem;
    border-radius: 10px;
}

.tab-btn {
    flex: 1;
    padding: 0.6rem;
    border: none;
    background: transparent;
    border-radius: 8px;
    font-weight: 500;
    color: var(--text-muted);
    cursor: pointer;
    transition: all 0.2s;
}

.tab-btn.active {
    background: var(--card-bg);
    color: var(--primary-color);
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.tab-contents {
    margin-bottom: 2.5rem;
}

.hidden {
    display: none !important;
}

.input-group {
    margin-bottom: 1.25rem;
}

.input-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

input[type="text"],
input[type="url"],
input[type="password"],
input[type="email"],
input[type="tel"],
select,
textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

textarea {
    min-height: 100px;
    resize: vertical;
}

.input-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.customization-panel {
    border-top: 1px solid var(--border-color);
    padding-top: 2rem;
}

.customization-panel h3 {
    font-size: 1.125rem;
    margin-bottom: 1.5rem;
}

.customize-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.full-width {
    grid-column: span 2;
}

.color-picker-wrapper {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

input[type="color"] {
    -webkit-appearance: none;
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 6px;
    cursor: pointer;
    background: none;
}

input[type="color"]::-webkit-color-swatch-wrapper {
    padding: 0;
}

input[type="color"]::-webkit-color-swatch {
    border: 1px solid var(--border-color);
    border-radius: 6px;
}

.file-input-container {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.btn-remove {
    padding: 0.5rem 1rem;
    background: #fee2e2;
    color: #ef4444;
    border: none;
    border-radius: 6px;
    font-size: 0.875rem;
    cursor: pointer;
}

.preview-panel {
    position: sticky;
    top: 2rem;
}

.preview-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    text-align: center;
}

.qr-container {
    background: #f1f5f9;
    padding: 1rem;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 2rem;
    min-height: 300px;
}

.qr-container canvas, 
.qr-container svg {
    max-width: 100% !important;
    height: auto !important;
    border-radius: 8px;
}

.download-actions {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}

.btn {
    padding: 0.875rem;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.btn-secondary {
    background: white;
    color: var(--text-main);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: #f8fafc;
}

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