need help with 2 1/2 yo bedtime tantrums

need suggestions to try to get my daughter to go to bed easier. used to sleep well on own, for past month having problems. She wants to play and resists sleep at bedtime. We've continued with the same bedtime routine we've had all along...rocking, reading a few books and going to bed with a couple stuffed animals and a book of her own. now she climbs out of bed and goes in search of us or her toys to play. we've tried sitting in the room with her and working our way out of the room until she goes to sleep--this worked briefly, now she just gets up and runs past us. we also tried putting a gate up in her room to block her in, but she would be up until midnight and after playing--even the next few days she did the same, so it's not like she got tired and slept better the next night. we've tried putting her in time outs every time she gets out of bed...at first my husband held her for time outs...he'd put her back to bed, she'd get out again and he'd hold her again and sche'd scream and cry until she fell asleep--we figured this was too reinforcing and she started hating being held by him, so now he's sitting her in her high chair with the high chair top locked in, to hold her in place for time out. but once we take her out an put her back in bed, she screams and cries and gets out again. i know time outs are only making her more upset and awake, but we're feeling desperate. she already refuses to go to bed before 9:30p because it's still light out and then she wakes up at 7a...so at best she sleeps 9hrs/night and generally takes a 1 1/2 or 2 hr nap everyday. i know she's tired and crabby in the morning now, and so am i. i feel we've tried everything. even just leading her by the hand back to bed, with no additional talk and said "nighty night" but she climbs back out of bed and gets to the door before we do to run out, so we can't even do the opening the door to check on her and remind her to stay in bed, because she's already out and running. any ideas?