/* ===================================================
   sg-extra-sections.css
   风华老唱片 · 复古黑胶风格定制版
   =================================================== */

/* ---------- 公共包裹 ---------- */
.sg-extra-wrap {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
    font-family: 'PingFang SC','Microsoft YaHei',system-ui,sans-serif;
    color: #f1f1f1;
}

/* ---------- 章节标题 ---------- */
.sg-ext-section-title {
    font-size: clamp(24px,4vw,34px);
    font-weight: 800;
    text-align: center;
    margin: 0 0 48px;
    position: relative;
    display: inline-block;
    left: 50%;
    transform: translateX(-50%);
    background: linear-gradient(135deg, #e8d5b7 0%, #d4a574 50%, #c49a6c 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    letter-spacing: 2px;
}
.sg-ext-section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0; right: 0;
    height: 3px;
    background: linear-gradient(90deg, transparent, #d4a574, #c49a6c, #d4a574, transparent);
    border-radius: 2px;
}
.sg-ext-section { margin-bottom: 72px; }
.sg-ext-section-sub {
    text-align: center;
    color: #b8a090;
    font-size: 15px;
    max-width: 700px;
    margin: -32px auto 48px;
    line-height: 1.8;
    font-style: italic;
}

/* ===================================================
   一、为什么选择 — 黑胶唱片风格 feature 卡片
   =================================================== */
.sg-feature-grid {
    display: grid;
    grid-template-columns: repeat(3,1fr);
    gap: 28px;
}
@media(max-width:900px){ .sg-feature-grid{ grid-template-columns:1fr 1fr; } }
@media(max-width:600px){ .sg-feature-grid{ grid-template-columns:1fr; } }

.sg-feature-card {
    backdrop-filter: blur(10px);
    background: linear-gradient(145deg, rgba(40,35,30,0.85) 0%, rgba(30,25,20,0.9) 100%);
    border: 1px solid rgba(212,165,110,0.15);
    border-radius: 20px;
    padding: 36px 30px;
    transition: all .4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    position: relative;
    overflow: hidden;
}
/* 黑胶唱片装饰角 */
.sg-feature-card::before {
    content: '';
    position: absolute;
    top: -30px;
    right: -30px;
    width: 100px;
    height: 100px;
    background: radial-gradient(circle, rgba(212,165,110,0.08) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}
.sg-feature-card:hover {
    border-color: rgba(212,165,110,0.4);
    transform: translateY(-8px);
    box-shadow: 0 20px 50px rgba(212,165,110,0.12), 0 0 0 1px rgba(212,165,110,0.1);
}
.sg-feature-icon-wrap {
    width: 64px; height: 64px;
    border-radius: 50%;
    background: linear-gradient(145deg, #d4a574 0%, #a67c52 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
    font-size: 24px;
    color: #1a1510;
    box-shadow: 0 6px 20px rgba(212,165,110,0.25), inset 0 1px 0 rgba(255,255,255,0.1);
    position: relative;
}
/* 唱片纹路效果 */
.sg-feature-icon-wrap::after {
    content: '';
    position: absolute;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    background: radial-gradient(circle, #1a1510 20%, transparent 21%, transparent 35%, #1a1510 36%, transparent 50%);
    background-size: 100% 100%;
    opacity: 0.3;
}
.sg-feature-card h4 {
    font-size: 20px;
    font-weight: 700;
    color: #f5ebe0;
    margin: 0 0 16px;
    letter-spacing: 1px;
}
.sg-feature-card p {
    color: #c4b5a5;
    font-size: 14px;
    line-height: 1.85;
    margin: 0 0 22px;
}
.sg-feature-link {
    color: #d4a574;
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
    transition: all .3s;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border-radius: 20px;
    background: rgba(212,165,110,0.1);
    border: 1px solid rgba(212,165,110,0.2);
}
.sg-feature-link:hover { 
    background: rgba(212,165,110,0.2);
    border-color: rgba(212,165,110,0.4);
    color: #e8c9a0;
    text-decoration: none;
    transform: translateX(4px);
}

/* ===================================================
   二、支持的音乐格式 — 黑胶风格 format 卡片
   =================================================== */
.sg-format-grid {
    display: grid;
    grid-template-columns: repeat(4,1fr);
    gap: 24px;
}
@media(max-width:1000px){ .sg-format-grid{ grid-template-columns:1fr 1fr; } }
@media(max-width:560px){  .sg-format-grid{ grid-template-columns:1fr; } }

.sg-format-card {
    border-radius: 20px;
    padding: 30px 24px;
    border: 1px solid transparent;
    transition: all .4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    position: relative;
    overflow: hidden;
}
/* 黑胶唱片中心孔装饰 */
.sg-format-card::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 180px;
    height: 180px;
    background: radial-gradient(circle, rgba(212,165,110,0.03) 0%, transparent 60%);
    border-radius: 50%;
    pointer-events: none;
}
.sg-format-card:hover { 
    transform: translateY(-6px); 
    box-shadow: 0 16px 40px rgba(0,0,0,0.3);
}

/* 各自配色 - 复古暖色调 */
.sg-format-card.hires  { 
    background: linear-gradient(180deg,rgba(220,165,120,0.08) 0%,rgba(40,35,30,0.6) 100%); 
    border-color: rgba(212,165,110,0.18); 
}
.sg-format-card.flac   { 
    background: linear-gradient(180deg,rgba(180,140,100,0.08) 0%,rgba(40,35,30,0.6) 100%); 
    border-color: rgba(180,140,100,0.18); 
}
.sg-format-card.dsd    { 
    background: linear-gradient(180deg,rgba(200,150,90,0.1) 0%,rgba(40,35,30,0.6) 100%); 
    border-color: rgba(200,150,90,0.22); 
}
.sg-format-card.wav    { 
    background: linear-gradient(180deg,rgba(160,130,100,0.08) 0%,rgba(40,35,30,0.6) 100%);  
    border-color: rgba(160,130,100,0.18); 
}

.sg-format-header { display: flex; align-items: center; margin-bottom: 18px; gap: 14px; }
.sg-format-badge {
    width: 54px; height: 54px;
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    font-weight: 800; font-size: 12px;
    flex-shrink: 0;
    position: relative;
    letter-spacing: 0.5px;
}
/* 唱片中心孔 */
.sg-format-badge::after {
    content: '';
    position: absolute;
    width: 10px;
    height: 10px;
    background: rgba(0,0,0,0.3);
    border-radius: 50%;
}
.sg-format-badge.hires  { 
    background: linear-gradient(145deg, #dca878 0%, #b8895a 100%);  
    color: #2a2015;
    box-shadow: 0 4px 12px rgba(212,165,110,0.25);
}
.sg-format-badge.flac   { 
    background: linear-gradient(145deg, #c4a070 0%, #9a7a50 100%);   
    color: #2a2015;
    box-shadow: 0 4px 12px rgba(180,140,100,0.25);
}
.sg-format-badge.dsd    { 
    background: linear-gradient(145deg, #e8c090 0%, #c49a60 100%);  
    color: #2a2015;
    box-shadow: 0 4px 12px rgba(200,150,90,0.3);
}
.sg-format-badge.wav    { 
    background: linear-gradient(145deg, #b09070 0%, #8a6a50 100%);   
    color: #2a2015;
    box-shadow: 0 4px 12px rgba(160,130,100,0.25);
}

.sg-format-header h4 { font-size: 19px; font-weight: 700; color: #f5ebe0; margin: 0; letter-spacing: 1px; }
.sg-format-card p    { color: #c4b5a5; font-size: 13px; line-height: 1.8; margin: 0; }

/* ===================================================
   三、音质与体积对比 — 黑胶唱片风格 quality 卡片
   =================================================== */
.sg-quality-grid {
    display: grid;
    grid-template-columns: repeat(3,1fr);
    gap: 24px 28px;
}
@media(max-width:900px){ .sg-quality-grid{ grid-template-columns:1fr 1fr; } }
@media(max-width:560px){ .sg-quality-grid{ grid-template-columns:1fr; } }

.sg-quality-card {
    backdrop-filter: blur(12px);
    border-radius: 20px;
    padding: 28px 24px;
    position: relative;
    overflow: hidden;
    transition: all .45s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    border: 1px solid rgba(212,165,110,0.08);
    background: linear-gradient(145deg, rgba(45,38,32,0.85) 0%, rgba(30,25,20,0.9) 100%);
}
/* 黑胶唱片装饰 */
.sg-quality-card::after {
    content: '';
    position: absolute;
    bottom: -40px;
    right: -40px;
    width: 120px;
    height: 120px;
    background: radial-gradient(circle, rgba(212,165,110,0.05) 0%, transparent 60%);
    border-radius: 50%;
    pointer-events: none;
}
.sg-quality-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 50px rgba(0,0,0,0.35), 0 0 0 1px rgba(212,165,110,0.15);
}
/* 顶部色条 */
.sg-quality-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 4px;
    opacity: .9;
    border-radius: 20px 20px 0 0;
}
.sg-quality-card.mp3::before    { background: linear-gradient(90deg,#8a7a6a,#6a5a4a); }
.sg-quality-card.cd::before     { background: linear-gradient(90deg,#d4a574,#c49464); }
.sg-quality-card.flac2::before  { background: linear-gradient(90deg,#c4a070,#b49060); }
.sg-quality-card.hires2::before { background: linear-gradient(90deg,#e8c090,#d8b080); }
.sg-quality-card.dsd2::before   { background: linear-gradient(90deg,#f0d4a0,#e0c490); }
.sg-quality-card.wav2::before   { background: linear-gradient(90deg,#b09070,#a08060); }

.sg-qc-head {
    display: flex; flex-direction: column;
    align-items: center; margin-bottom: 20px; gap: 12px;
}
.sg-qc-head h4 { font-size: 18px; font-weight: 700; margin: 0; text-align: center; letter-spacing: 1px; }

/* 颜色变量 - 复古暖色调 */
.sg-quality-card.mp3    .sg-qc-head h4 { color: #a09080; }
.sg-quality-card.cd     .sg-qc-head h4 { color: #e8c9a0; }
.sg-quality-card.flac2  .sg-qc-head h4 { color: #ddc090; }
.sg-quality-card.hires2 .sg-qc-head h4 { color: #f0d8b0; }
.sg-quality-card.dsd2   .sg-qc-head h4 { color: #f5e0c0; }
.sg-quality-card.wav2   .sg-qc-head h4 { color: #d4c4a4; }

.sg-qc-icon { font-size: 28px; opacity: .7; }
.sg-quality-card.mp3    .sg-qc-icon { color: #8a7a6a; }
.sg-quality-card.cd     .sg-qc-icon { color: #d4a574; }
.sg-quality-card.flac2  .sg-qc-icon { color: #c4a070; }
.sg-quality-card.hires2 .sg-qc-icon { color: #e8c090; }
.sg-quality-card.dsd2   .sg-qc-icon { color: #f0d4a0; }
.sg-quality-card.wav2   .sg-qc-icon { color: #b09070; }

.sg-qc-param, .sg-qc-size {
    margin-bottom: 14px;
    padding: 14px;
    border-radius: 12px;
    background: rgba(0,0,0,0.25);
    text-align: center;
    border: 1px solid rgba(212,165,110,0.06);
}
.sg-quality-card.mp3    .sg-qc-param, .sg-quality-card.mp3    .sg-qc-size { border-color: rgba(138,122,106,0.2); }
.sg-quality-card.cd     .sg-qc-param, .sg-quality-card.cd     .sg-qc-size { border-color: rgba(212,165,116,0.2); }
.sg-quality-card.flac2  .sg-qc-param, .sg-quality-card.flac2  .sg-qc-size { border-color: rgba(196,160,112,0.2); }
.sg-quality-card.hires2 .sg-qc-param, .sg-quality-card.hires2 .sg-qc-size { border-color: rgba(232,192,144,0.2); }
.sg-quality-card.dsd2   .sg-qc-param, .sg-quality-card.dsd2   .sg-qc-size { border-color: rgba(240,212,160,0.2); }
.sg-quality-card.wav2   .sg-qc-param, .sg-quality-card.wav2   .sg-qc-size { border-color: rgba(176,144,112,0.2); }

.sg-qc-param p:first-child, .sg-qc-size p:first-child { font-size: 12px; font-weight: 600; color: #c4b5a5; margin: 0 0 4px; text-transform: uppercase; letter-spacing: 1px; }
.sg-qc-val { font-size: 16px; font-weight: 700; margin: 0; }
.sg-quality-card.mp3    .sg-qc-val { color: #a09080; }
.sg-quality-card.cd     .sg-qc-val { color: #e8c9a0; }
.sg-quality-card.flac2  .sg-qc-val { color: #ddc090; }
.sg-quality-card.hires2 .sg-qc-val { color: #f0d8b0; }
.sg-quality-card.dsd2   .sg-qc-val { color: #f5e0c0; }
.sg-quality-card.wav2   .sg-qc-val { color: #d4c4a4; }

.sg-qc-features { font-size: 12px; color: #a09080; }
.sg-qc-features p { display: flex; align-items: center; margin: 0 0 8px; gap: 8px; line-height: 1.5; }
.sg-qc-features p:last-child { margin: 0; }
.sg-qc-check { color: #b8a070; font-size: 11px; }
.sg-qc-cross { color: #c08080; font-size: 11px; }

/* 底部提示 */
.sg-quality-tip {
    margin-top: 40px;
    padding: 20px 28px;
    border-radius: 16px;
    background: linear-gradient(90deg, rgba(212,165,110,0.06) 0%, rgba(180,140,100,0.04) 50%, rgba(212,165,110,0.06) 100%);
    border: 1px solid rgba(212,165,110,0.15);
    text-align: center;
    color: #c4b5a5;
    font-size: 14px;
    line-height: 1.7;
    letter-spacing: 0.5px;
}
.sg-quality-tip i { color: #d4a574; margin-right: 8px; }

/* 入场动画（复用 script.js 的观察器） */
.sg-extra-wrap .sg-feature-card,
.sg-extra-wrap .sg-format-card,
.sg-extra-wrap .sg-quality-card {
    opacity: 1;
    transform: translateY(0);
    transition: opacity .55s ease, transform .55s ease, border-color .3s, box-shadow .3s;
}
.sg-extra-wrap .sg-feature-card.sg-visible,
.sg-extra-wrap .sg-format-card.sg-visible,
.sg-extra-wrap .sg-quality-card.sg-visible {
    opacity: 1;
    transform: translateY(0);
}