/* 基础样式 */
:root {
    color-scheme: dark;
    --accent: #3b82f6;
    --accent-strong: #2563eb;
    --surface: rgba(20, 24, 31, 0.74);
    --text: #f5f7fb;
    --muted: #a3b0c2;
}

body {
    font-family: 'Segoe UI', 'Google Sans', 'Roboto', sans-serif;
    margin: 0;
    padding: 20px;
    background: linear-gradient(135deg, rgba(59,130,246,0.18), transparent 38%), linear-gradient(320deg, rgba(8,15,24,0.98), rgba(14,20,29,0.96));
    color: var(--text);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    background: radial-gradient(circle at top left, rgba(59,130,246,0.16), transparent 30%);
    pointer-events: none;
}

.container {
    text-align: center;
    background: linear-gradient(145deg, rgba(255,255,255,0.10), rgba(255,255,255,0.04));
    border: 1px solid rgba(255,255,255,0.12);
    padding: 48px 56px;
    border-radius: 28px;
    box-shadow: 0 18px 45px rgba(0,0,0,0.24);
    backdrop-filter: blur(18px);
    animation: fadeIn 0.3s ease-in-out;
    max-width: 92vw;
    width: min(900px, 92vw);
    margin: 0 auto;
}

.time {
    font-size: 190px;
    margin: 0;
    color: #ffffff;
    font-weight: 500;
    letter-spacing: 0.02em;
    text-shadow: 0 8px 24px rgba(0,0,0,0.25);
}

.text {
    font-size: 2rem;
    margin-bottom: 24px;
    color: var(--text);
    font-weight: 600;
}

.controls {
    margin-top: 34px;
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
}

.btn,
#fontSelector {
    padding: 10px 16px;
    border: 1px solid rgba(255,255,255,0.12);
    border-radius: 999px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.95rem;
    font-weight: 600;
    background: rgba(255,255,255,0.08);
    color: var(--text);
    box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}

.btn:hover,
#fontSelector:hover {
    background: rgba(59,130,246,0.2);
    color: #fff;
    transform: translateY(-1px);
    border-color: rgba(59,130,246,0.35);
}

#fontSelector {
    padding: 10px 14px;
    background: rgba(20, 24, 31, 0.92);
    color: var(--text);
    border: 1px solid rgba(255,255,255,0.12);
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
}

#fontSelector option {
    background: rgba(20, 24, 31, 0.98);
    color: var(--text);
}

.btn.fullscreen {
    background: var(--accent);
    color: #fff;
}

.btn.fullscreen:hover {
    background: var(--accent-strong);
}

#return-btn {
    position: absolute;
    top: 20px;
    left: 20px;
    padding: 10px 16px;
    font-size: 0.95rem;
    cursor: pointer;
    background: rgba(255,255,255,0.08);
    color: var(--text);
    border: 1px solid rgba(255,255,255,0.12);
    border-radius: 999px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.12);
    transition: all 0.2s ease;
    z-index: 1001;
    backdrop-filter: blur(12px);
}

#return-btn:hover {
    background: rgba(59,130,246,0.2);
    color: #fff;
    transform: translateY(-1px);
    border-color: rgba(59,130,246,0.35);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.font-size-control {
    display: flex;
    align-items: center;
    gap: 6px;
}

#fontSizeInput {
    width: 78px;
    text-align: center;
    padding: 10px 8px;
    background: rgba(255,255,255,0.06);
    color: var(--text);
    border: 1px solid rgba(255,255,255,0.12);
    border-radius: 12px;
}

.unit {
    color: var(--muted);
    font-size: 0.9rem;
}

#TimeAPI-status {
    color: var(--muted);
    margin-left: 12px;
    font-size: 13px;
}