/* Base styles and resets */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--primary-color);
    color: var(--text-color);
    min-height: 100vh;
    font-size: 14px;
    line-height: 1.5;
    transition: background var(--transition-speed), color var(--transition-speed);
}

[data-theme="dark"] body {
    background: linear-gradient(135deg, #0f1419 0%, #1a2332 100%);
}

[data-theme="light"] body {
    background: linear-gradient(135deg, #f5f7fa 0%, #ffffff 100%);
}

a {
    color: var(--accent-color);
    text-decoration: none;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    color: var(--text-color);
}

h1 { font-size: 24px; }
h2 { font-size: 18px; }
h3 { font-size: 16px; }
h4 { font-size: 14px; }

/* Lists */
ul, ol {
    list-style: none;
}

/* Forms */
input, select, textarea, button {
    font-family: inherit;
    font-size: inherit;
}

/* Tables */
table {
    border-collapse: collapse;
    width: 100%;
}

/* Images */
img {
    max-width: 100%;
    height: auto;
}

/* Section visibility */
section {
    display: none;
    margin-bottom: var(--spacing-xl);
}

section.active {
    display: block;
}