:root {
    --bg: #f0f2f5;
    --card: #ffffff;
    --primary: #4CAF50;
    --primary-dark: #3e9c43;
    --primary-active: #144917;
    --border: #ddd;
}
body {
    font-family: "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    margin: 0;
    padding: 30px;
}
.container {
    max-width: 950px;
    margin: auto;
    background: var(--card);
    padding: 25px 30px;
    border-radius: 12px;
    box-shadow: 0 8px 18px rgba(0,0,0,0.08);
}
h1 {
    text-align: center;
    margin-bottom: 25px;
    font-weight: 600;
    color: #333;
}
section {
    margin-bottom: 35px;
}
h2 {
    border-bottom: 2px solid var(--border);
    padding-bottom: 6px;
    margin-bottom: 18px;
    color: #444;
}
label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}
input[type="file"],
select,
textarea {
    width: 100%;
    padding: 10px 12px;
    margin-bottom: 15px;
    border: 1px solid var(--border);
    border-radius: 6px;
    box-sizing: border-box;
    font-size: 15px;
}
textarea {
    resize: vertical;
    min-height: 120px;
    max-height: 220px;
    overflow-y: auto;
}
.channel-options {
    display: flex;
    gap: 20px;
    margin-bottom: 15px;
}
.channel-options label {
    font-weight: normal;
}
button {
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 6px;
    padding: 12px 20px;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.2s ease;
}
button:hover {
    background: var(--primary-dark);
}
#downloadTextBtn { margin-top: 10px; }
canvas { display: none; }

.tabs {
    display: flex;
    margin-bottom: 20px;
    border-bottom: 2px solid var(--border);
}

.tab-btn {
    flex: 1;
    background: var(--primary);
    border: none;
    padding: 12px;
    font-size: 16px;
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: 0.2s;
    margin: 10px;
}

.tab-btn.active {
    border-bottom: 3px solid var(--primary-active);
    font-weight: bold;
}

.tab-content {
    display: none;
}
.tab-content.active {
    display: block;
}