:root {
    --card-bg-dark: #24243a;
    --card-bg-light: #f5f7fa;
    --text-dark: #fff;
    --text-light: #222;
    --accent: #008cff;
    --input-bg-dark: #292b3e;
    --input-bg-light: #e6e9ef;
    --border-radius: 18px;
    --box-shadow: 0 6px 30px #0003;
}
body {
    margin: 0;
    min-height: 100vh;
    font-family: 'Segoe UI', sans-serif;
    background: linear-gradient(145deg, #181828 40%, #282843 100%);
    color: var(--text-dark);
    transition: background 0.3s, color 0.3s;
}
.light-theme {
    background: linear-gradient(145deg, #e4ecfa 40%, #f7fafc 100%);
    color: var(--text-light);
}
.theme-toggle {
    position: absolute;
    top: 24px;
    right: 32px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 50px;
    padding: 10px 22px;
    font-weight: 600;
    box-shadow: 0 2px 12px #008cff40;
    cursor: pointer;
    transition: background 0.2s;
}
.container {
    max-width: 450px;
    margin: 70px auto 0 auto;
    background: var(--card-bg-dark);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 30px 36px 38px 36px;
    text-align: center;
    transition: background 0.3s, color 0.3s;
}
.light-theme .container {
    background: var(--card-bg-light);
    color: var(--text-light);
}
h2 {
    margin-bottom: 15px;
    font-size: 2.1em;
    letter-spacing: 0.03em;
    font-weight: 700;
}
form {
    margin-bottom: 20px;
}
.options {
    display: grid;
    grid-template-columns: repeat(2,1fr);
    gap: 10px 20px;
    margin: 20px 0;
}
.options label {
    font-size: 1em;
    display: flex;
    align-items: center;
}
input[type="number"], input[type="checkbox"] {
    margin-right: 8px;
}
input[type="number"] {
    border: none;
    border-radius: 7px;
    background: var(--input-bg-dark);
    color: var(--text-dark);
    padding: 7px 10px;
    width: 62px;
    font-size: 1.1em;
    outline: none;
    transition: background 0.3s, color 0.3s;
}
.light-theme input[type="number"] {
    background: var(--input-bg-light);
    color: var(--text-light);
}
.generate-btn {
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 10px;
    padding: 13px 30px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    margin-top: 10px;
    transition: background 0.2s;
    box-shadow: 0 3px 14px #008cff40;
}
.generate-btn:hover {
    background: #0062b1;
}
.password-card {
    margin: 30px 0 12px 0;
    padding: 16px 18px;
    background: #14152a;
    color: #03fcf4;
    border-radius: 12px;
    font-size: 1.35em;
    letter-spacing: 0.07em;
    box-shadow: 0 2px 8px #008cff30;
    word-break: break-all;
    user-select: all;
}
.light-theme .password-card {
    background: #c9f0ff;
    color: #005b89;
}
.copy-btn {
    margin-top: 0;
    background: #03c9fc;
    color: #fff;
    border: none;
    border-radius: 7px;
    padding: 9px 18px;
    font-size: 1em;
    cursor: pointer;
    margin-left: 8px;
    transition: background 0.18s;
}
.copy-btn:hover {
    background: #0090b9;
}