:root {
    --bg: #0d1117;
    --bg2: #161b22;
    --text: #e6edf3;
    --accent: #5865f2;
    --success: #238636;
    --border: #30363d;
    --muted: #8b949e;
}
body.light {
    --bg: #ffffff;
    --bg2: #f5f5f5;
    --text: #111111;
    --accent: #5865f2;
    --border: #d0d7de;
    --muted: #57606a;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: 'Inter', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: all 0.3s;
}
header {
    background: var(--bg2);
    padding: 20px 24px;
    text-align: center;
    border-bottom: 1px solid var(--border);
    position: relative;
}
.back-home {
    position: absolute;
    left: 24px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    font-size: 15.5px;
    transition: opacity 0.2s;
}
.back-home:hover { opacity: 0.8; }
header h1 {
    font-size: 28px;
    font-weight: 700;
}
.container {
    max-width: 900px;
    margin: 60px auto;
    padding: 0 24px;
    flex: 1;
}
.tabs {
    display: flex;
    gap: 14px;
    margin-bottom: 40px;
    flex-wrap: wrap;
    justify-content: center;
    padding: 0 10px;
}
.tab {
    padding: 14px 28px;
    background: var(--bg2);
    border: 1.5px solid var(--border);
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s;
    font-weight: 600;
    font-size: 15.5px;
    min-width: 160px;
    text-align: center;
}
.tab:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}
.tab.active {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
    box-shadow: 0 8px 20px rgba(88,101,242,0.3);
}
.form-container {
    background: var(--bg2);
    padding: 40px 36px;
    border-radius: 18px;
    border: 1px solid var(--border);
    display: none;
    animation: fadeIn 0.5s ease forwards;
}
.form-container.active { display: block; }
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: none; }
}
h2 {
    font-size: 30px;
    margin-bottom: 16px;
    color: var(--accent);
    text-align: center;
    font-weight: 700;
}
p.subtitle {
    opacity: 0.88;
    margin-bottom: 32px;
    text-align: center;
    font-size: 17px;
    max-width: 680px;
    margin-left: auto;
    margin-right: auto;
}
label {
    display: block;
    margin-bottom: 10px;
    font-weight: 600;
    font-size: 15.5px;
    color: var(--text);
}
input, textarea, select {
    width: 100%;
    padding: 14px 18px;
    background: var(--bg);
    border: 1.5px solid var(--border);
    border-radius: 12px;
    color: var(--text);
    font-size: 16px;
    margin-bottom: 24px;
    transition: all 0.3s;
}
input:focus, textarea:focus, select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 4px rgba(88, 101, 242, 0.18);
    transform: translateY(-1px);
}
textarea {
    min-height: 160px;
    resize: vertical;
    font-family: inherit;
}
button[type="submit"] {
    background: var(--accent);
    color: white;
    padding: 16px 32px;
    border: none;
    border-radius: 12px;
    font-weight: 700;
    font-size: 16.5px;
    cursor: pointer;
    transition: all 0.3s;
    width: 100%;
    margin-top: 10px;
}
button[type="submit"]:hover {
    opacity: 0.92;
    transform: translateY(-3px);
    box-shadow: 0 10px 25px rgba(88,101,242,0.4);
}
.success-message {
    background: var(--success);
    color: white;
    padding: 32px;
    border-radius: 18px;
    text-align: center;
    font-size: 20px;
    font-weight: 600;
    margin-top: 30px;
    display: none;
    animation: fadeIn 0.6s;
}
.success-message.show { display: block; }

footer {
    margin-top: auto;
    background: var(--bg2);
    padding: 50px 20px 40px;
    text-align: center;
    border-top: 1px solid var(--border);
    font-size: 15px;
    opacity: 0.9;
}

/* Responsive */
@media (max-width: 768px) {
    header { padding: 18px 20px; }
    header h1 { font-size: 26px; }
    .back-home { left: 20px; }
    .container { margin: 50px auto; padding: 0 20px; }
    .tabs { gap: 12px; }
    .tab { padding: 12px 22px; font-size: 15px; min-width: 140px; }
    .form-container { padding: 32px 28px; }
    h2 { font-size: 28px; }
}

@media (max-width: 480px) {
    header { padding: 16px; text-align: center; }
    .back-home {
        position: static;
        transform: none;
        display: block;
        margin-bottom: 12px;
        font-size: 16px;
    }
    header h1 { font-size: 24px; }
    .container { margin: 40px auto; padding: 0 16px; }
    .tabs {
        flex-direction: column;
        align-items: center;
        gap: 12px;
    }
    .tab {
        width: 100%;
        max-width: 300px;
        padding: 14px 20px;
    }
    .form-container { padding: 28px 20px; border-radius: 16px; }
    h2 { font-size: 26px; }
    p.subtitle { font-size: 16.5px; }
    input, textarea, select { padding: 13px 16px; font-size: 15.5px; }
    button[type="submit"] { padding: 15px 20px; font-size: 16px; }
    .success-message { padding: 28px; font-size: 18px; }
}